Connecting Batteries with DIFFERENT Capacity in Parallel - What Happens?!

[@vincentrobinette1507]

Don't sweat the BMS continuous current rating too much. As a rule, the equivalent resistance of LiFEPO4 batteries is largely inversely proportionate to their capacities. The batteries will mostly current share, with the smaller battery only producing it's percentage of overall capacity in current. In this configuration, if you used a DC clamp meter on the output terminals of each battery, The smaller battery would show about 18% of the total draw of the inverter, while the larger battery would supply about 82% of the current. If the big battery has a 250 amp current limit, the small battery only needs to be about 55 amps, to allow full loading of the bigger battery management system. (BMS)

[@AdministrativeReload]

This is accurate. I run a system with different capacity batteries in parallel connected through bus bars and it behaves exactly as you described.

[@vk3fbab]

I would have expected it to behave this way. Because both batteries will be at almost identical voltage the current flow will be greater from the greater capacity battery. It's not common you see this configuration but nothing wrong with it.

[@yvesinformel221]

It should be true that lower capacity as higher resistance, but different manufacturers may have different resistance for the same capacity

[@hozn]

I know some of those words 😌

[@angryman3317]

Pretty much exactly what I was going to say, no joke almost Word for Word but in a slightly different order.

[@thomasmaughan4798]

"DIFFERENT Capacity in Parallel - What Happens?!" Provided they have the same voltage, *nothing happens* . As you draw power, the one with less capacity will start to drop voltage, but of course, it cannot; so most of the load starts drawing from the battery with more capacity. Thus, their SOC (state of charge) draws down uniformly.

[@ahmetmutlu348]

well when i connect them i see lots of power leak from higher one to smaller one as smaller ones voltahe is in general less even if charged full there is small change... you can use a voltmeter and ampermeter to check the voltage difference ..

[@matb748]

​@@ahmetmutlu348so you saying that full charge voltage is not same for Comparison of a 10 amp and 40 amp battery? 😮

[@PM-wt3ye]

@@ahmetmutlu348thats just nonsense… Capacity has nothing to do with voltage. AGM batteries, 40Ah, 90Ah, 120Ah ALL have ~12,9V when new and fully charged

[@ahmetmutlu348]

​@@PM-wt3yeIm not sure.. but when i left them unmonitored things goes wrong in general and i suspected that they are discharging each other and checked voltage flow and i allmost allways see lots of power flow from one to another... if you have time you can make may be an arduino that creates statistics for how that goes.😊 but there is allmost allways atleast 0.5 volts flow from one to another may not be a problem of you charge them regularly anyway... may be thats what they call self discharge pr whatewer but what ive seen is they do discharge a lot.😊

[@ahmetmutlu348]

​@@matb748I dont have detailed stats but you can do the test yourself.. connect 2 batteries in paralel and use a voltmeter or led on one of the cables serially... youll see led will light up indicating discharge from one to another.

[@vinny143]

Im running 28 12.8v Li Time batteries in parallel, 4 batteries / 7 individual shunts. Hooked to 5 renogy inverters. 2- 3000 watt 2- 1000 watt 1- 2000 watt They are running dedicated rooms in our off grid cabin. Hope to have a single 18k EG4 the first of next year , to run our electric stove , clothes dryer and water heater. I enjoy your informative videos

[@jensschroder8214]

You have to imagine it like this. The large battery is a wide container for energy, the small battery is a narrow container for energy. Now you connect both in parallel, this equalizes the height of energy (Volt), but the width of the batteries remains the same. When unloading, both are unloaded in height (Volt), but the Ampere balance each other out. To the point where both are empty. Due to the internal resistance, the cells can discharge at different rates. But things even out again.

[@sonofbr]

I have been researching this question for years and this is the first time I've found a solid answer. Thank you.

[@stinkycheese804]

Years? I could have found the answer in 5 minutes with a google search, but I already knew.

[@sonofbr]

@@stinkycheese804 The first GOOD answer I found. I guess your googling works better. I was complimenting the video creator, not inviting snarky comments.

[@somcho]

me too

[@makantahi3731]

those are the basics of electrical engineering, I don't remember if I learned it in elementary school or just in high school, if you're still in kindergarten, don't worry, that will come later

[@sonofbr]

@@makantahi3731 I'm not an electrical engineer, so I look for answers. If you learned about lithium battery balancing and charging and what can affect their capacities in the long-term in elementary school, wow.

[@kbjerke]

While I already knew this, I'm really happy with your demonstration that proves it beyond doubt. Thank you!! 👍

[@occamraiser]

And I use lead acid car batteries so doing that test for myself would risk damaging them if my home made chinese low voltage cut-off / 200A relay combo lets me down.

[@herb7877]

Great info. I pretty much thought this was the case but never tested it. Nice to have it confirmed...

[@OttoLP]

Adding a 200 and 100 amp bms battery in parrallel means you can draw over 200 amps since the load is distributed across both batteries.

[@PeterMenzies-t4r]

Great informative video & advice, thanks. It would have been good to also monitor the current share between the two batteries and graph the battery voltage till drop off & shutdown.

[@curtbrown9702]

Also. From last question. If need i can use separate invertors on a on, off as needed for different items. If needed the pull on batteries will be hi at times so i want to keep toped of, or at least helping them from a high drain.

[@DNTMEE]

One thing to keep in mind is the voltage difference between the two batteries under use. For example, if the voltage output of the smaller battery falls below the voltage output of the large battery, the large battery will end up charging the smaller battery instead of putting all it's current output towards the load. The usual way to prevent this is through the use of so-called "steering diodes." This prevents one battery from discharging some or all of it's current output into another battery. Unfortunately it also lowers the overall output voltage by 0.7 volts for each diode that ends up being between the final output from the batteries and the load.

[@mychannelgoaway2833]

The use of Schottky diodes drops this to about ~0.2VDC.

[@thomasmaughan4798]

"the large battery will end up charging the smaller battery instead of putting all it's current output towards the load." While unlikely, this is also harmless; since the *charge* is still available to the load.

[@holyscrap4445]

Yeah but there will be a drop in efficiency due to losses caused by the larger battery charging the small one. Though the efficiency will be a lot lower than the one caused by the diodes.

[@thomasmaughan4798]

@@holyscrap4445 "but there will be a drop in efficiency due to losses caused by the larger battery charging the small one." It is unlikely the larger one tries to charge the smaller one. As I explained already, what will happen is the rate of discharge of the smaller battery will decline faster than the rate of discharge of the larger battery simply because of the higher internal resistance of the smaller battery. Thus, both batteries will deplete their proportion of charge at about the same rate; the larger battery will be at 2/3 charge and the smaller battery will also be at 2/3 charge and their voltages will still be the same. Thus, each battery provides current into the load proportional to their internal resistance and neither battery will attempt to charge the other. Only in the case that you have a fully charged battery connected to a depleted battery will one charge the other, and it won't matter which is *larger* what matters is which has the higher voltage. But connected to a load, each battery will drive the load and not each other. Steering diodes will certainly help when *charging* the batteries also in the case that their voltages are not the same (different chemistry or ages).

[@davidsoulsby1102]

@@thomasmaughan4798 Its actually true and is the reason you should always use matched batteries when they are not rechargeable for obvious reasons. The secret is separate BMS for each battery. Don't try to use one BMS for both batteries.

[@shelley131]

Well I just learned something new. Which is why I am subscribed to your channel. Great information to know. I am glad that when you do this type of videos, they are directed to the novice audiences getting into solar power and batteries and you do not assume that we already know. Great, great explanation and great job.

[@miken7629]

On my Harley I added a capacitor in parallel with the battery, without the cap the starter always seems to run down the battery when starting, with capacitor starter turns over like it should. Capacitor in parallel is good for heavy startup loads like when the starter motor kicks in or when an inverter kicks in to run a refrigerator, when a motor starts initially it is similar to a dead short.

[@nickwinn7812]

True, but it needs to be a super cap to hold enough juice to be useful. The downside is that super caps can be pretty dangerous, simply because of the rate at which they can discharge, that is a short circuit will make a very big bang and at higher voltages a shock will be lethal.

[@miken7629]

@@nickwinn7812 On my Harley I used a 10,000 UF 25v electrolytic capacitor and it makes a difference because motorcycle batteries are so small. For a Truck they make 16v Audio Capacitors that are .5 farad and above, they ususally have a voltage display that would be a voltage drain while engine is off, I would remove that part then use just the plain capacitors and attach parallel to battery with short leads.

[@nickwinn7812]

@@miken7629 Do as you please, just know that large capacitors hold nasty surprises for the unwary.

[@makantahi3731]

do not mix the two cases because they are not the same, the capacitor on the ac motor serves to compensate for the reactive current and not as an additional energy reserve

[@nickwinn7812]

@@makantahi3731 What 2 cases do you think we are mixing here? Nobody is talking about motor capacitors. An HD starter motor is a DC brushed motor and has no capacitor in any case.

[@Heal-inn]

Thanks for the video! Why is series not possible? Would be great to at a extra battery to a exciting 12v bank so there is 24v available. The big battery is common for 12v and 24v, the smal one only for 24v. Charged with 2 12v chargers. Would love to see that tested..

[@NCmountainview]

Great video! This works out because the internal resistance of the cell is lower for the battery with the larger ampacity. In other words more of the load is drawn from the larger cell battery. That is why the experiment worked, and different sized batteries in parallel discharged in the same time frame. It can even help balance out the surge scenario, as more of the load comes from the battery with the lower internal resistance. However, it is still great advice and wise to avoid major imbalances in the lead acid batteries and not to mix types. It is also important to note the age and condition impact the internal resistance, and the health of the cells can effect how well they play together.

[@jritchie777]

Damn, I've always wondered about that. Great experiment, valuable info. Good to know if you happen to be in an emergency situation and have access to multiple batteries.

[@leeinwis]

You got scared didn't you ?

[@Rabs73]

That battery is a monster. Nice video thanks

[@joesawyer931]

This is helpful as I was contemplating buying a second lead acid deep cycle 12 volt battery to put in parallel with the one that came with my RV. I wasn't sure how closely I needed to match the original battery. Apparently it's not that critical

[@Paul-FrancisB]

That's exactly what I did for my touring caravan to maximise the benefit when charging from either the car or the PV panels, not had any issues and over doubled the time I can run without a mains hookup

[@QUIX4U]

To both you and @Paul-FrancisB What neither of you have done (or intend to do) has a daul battery isolator in the charging circuit (from the alternator), as they will just become as if a single battery bank, that could well go "below" the required vehicle starting voltage, with a result of being unable to recharge anything, if away from a mains recharging facility. It's far better in an RV to have a battery isolator in the form of a dual battery circuit, where if needed, you can switch across between one battery or the other, or if a vehicle's battery gets drained (you accidentally leave the lights on or similar) you can JUMP the vehicle's battery with the RV's on-board house battey, just enough to restart the vehicle to recharge the main 1st until it's nearly recharged, and then the dual battery isolator automatically switches the 2nd battery (the house battery) into the charging circuit, to then recharge both batteries. Having both interconnected as if a single batter, may sound easy, but overdraining the house battery, will also drain the vehicle's battery, and visa versa, often well below the capability to restart the vehicle. Having a dual battery isolater connected, you will also more than likely have some way of having a low battery alarm, on at least the vehicle's battery, if not on both batteries. TO WARN if either one is getting too low Then you should quickly restart the vehicle, to recharge both to a suitable level - to ensure that you aren't marooned with two flat batteries and a dead motor

[@Paul-FrancisB]

@@QUIX4U hi you have mis read my reply, I don't have an RV it is a Car and Caravan. 2 batteries in the caravan in parallel, as it is 12V. The car, oddly has 2 manufacturer fitted batteries also, Mercedes 280 (the 2nd smaller one is for the ABS and self levelling suspension). The auxiliary power (blue wire in the UK) is only energised for charging and the fridge if the alternator is charging. The caravan (camper trailer, I believe the American phrase is) cannot drain the car batteries. The solar can top up the leisure batteries if it is sunny, a rare event in the UK, or the mains hookup if available. I hope this helps you understand my reply. My understanding of the OP is he was going to double up the leisure (deep cycle) battery in the RV, and not mess with the engine starting battery or the split charge system if he has one. So he would have 3 batteries in total.

[@jam5158]

@@Paul-FrancisB So isn't a caravan just a European RV, which we also denote as tow behind trailers? Anyway don't waste your money buying another lead acid battery when you would be better off getting lithiums. You can actually get the same continuous current from one lithium as you can from two lead acid. Lithium can be run down to 0% and not hurt the capacity. Where lead acid will lose capacity when the level goes below 50%. It will usually lose about %20 capacity the first time you take it down below 50% and continue to lose capacity each time you go below 50%.

[@BritishBeachcomber]

If you've got a leisure battery fitted then it's in parallel with the main battery whenever it's charging. Never a problem.

[@cll1out]

What you said about the issues with different batteries in series explains why consumer electronics that use disposable alkalines tell you not to mix old and new, different brands etc. I think as kids many of us have experienced what happens when you violate those rules and the chemistries decide to leave the batteries.

[@markoshun]

‘Chemistries decide to leave batteries’ By this do you just mean leaks and corrosion?

[@johncunningham4820]

Exactly what I thought , but REALLY well explained for those those that have no Technical background .

[@gordony8196]

Thanks. I always find your videos interesting, informative and practical.

[@bytornsnowdog2112]

Great demonstration. Thank you!

[@danielking2944]

I built a 120 AH LFP first then later a 280 AH. I’ve had EG4 100 AH server rack batteries paralleled at times also . As long as the individual bms protects its battery,the pool of energy is fine. In solar power systems in homes with a large battery bank the amp draw never challenges the battery. My combined 400AH battery is currently running a 5KW inverter that seldom runs over 75% capacity. Even if the smaller battery carried the whole load, it would still be discharging at less than 1C. Certainly there are ways to maximize the efficiency to avoid conversion loss,but solar panels have become so cheap that my focus is safety and lifespan of the system by never push any component to its limit.

[@JOHNDANIEL1]

As you will see in my videos, my channel, for years I have Lead acid AND LiFePO4 running in one bank. 13 LiFePO4 Batteries connected to one main buss bar. 2 @ 400ah, 5 @ 200ah and 6 are 100ah. Been running fine for over 26 months. The method is your cable sizing. You use resistive cable gauging to keep them working together. 6 awg from each 100ah, 4 awg from each 200ah, and 2 awg from each 400ah. The outcome is defaulted charge and draw due to wire/ load resistance(heat). As you demand too much from the 100ah, the 6 awg starts to "road block" basically resist pull over 70 amps and defaults to the 200ah, the 200 ah 4 awg starts to get resistance in its cable when you exceed 125 amps and defaults to the 400ah using 2 awg. It all auto balances itself to the main buss bar so I get 70% ability of all the BMS's at the same time as it is in use. to make matters even more insane, for almost 2 years I have 28 GC2 Rolls Surrettes 235ah Lead Acid Batteries connected via 2/0 cable to those LiFePO4 Buss Bar. The inverters and all loads pull direct from the Lead Acid which gets its voltage support ( not its main amp draw ) from the Lithium. My total result is thousands of Amp hours. The Lead Acid is like new even though 3-1/2 years old since they have voltage support and never see over 45% DOD. They even now have 1/3 the water loss due to the LiFePO4 all night supporting voltage stability refill. I learned this in the Telecom industry when they used Ni-mh for lead acid support the same way in the 1990's.

[@2hotscottpro]

I watched you explain a lot of good info on yer channel.😊

[@juliancouch5891]

When you connect two batteries in parallel over a long period with no demand, is there a risk of one battery continually trying to charge the other?

[@QUIX4U]

No, if you connected all the batteries using a 6" x 1/2" COPPER BUS BAR, they would all deplete at exactly the same % each, irrespective of "rated current loading", because if the LOAD is more than the smallest battery, IT IS NOT SUPPLYING ALL OF THAT LOAD, just a small percentage of the over-rated load. THINK, all a battery is, is a container with a specified rated current at a certain voltage. One can use see-through plastic water containers, (instead of batteries) such as using ALL at a 1M height - but of different diameters, or shapes, (or squares shapes too, as that's what an IBC is, a square pipe 1M high) such that ALL will be filled to maximum height (1M) before you open the combined drain pipes, to drain at whatever rate your "output loading" is, thus if you draw far more "capaciy" than your smallest container's capacity, don't worry at all, because that IS NOT the only container there. It will NOT drain it's capacity any faster than any other, so when your smallest battery gets to HALF of it's capacity - all others will also be at 50%. ALL will be self-balanced (at that same 50% level), thus there will also be no "intercharging (flow) effects" either, between any two. There is no need as all will have the same height of upper water levels, (which is comparible to a batteries toal capacity left) - meaning that no ONE battery will be supplying anything to any other, with them ALL at the same % capacity left. THE PROBLEM IS THIS, many people assume, that because they are using 12v batteries, they can combine NEW fully charged batteries, with depleted ones, to get the shock (quite literally) of their lives, when a MASSIVE instantainious flow occurs, between the fully charged batteries and the depleted ones, that ARE NOW BEING RECHARGED by the new batteries, far beyond the "rated capacities of the new batteries, causing THEM to explode. The recharging one's won't explode as they still aren't fully recharged, and never will be if the new batteries explode.

[@JOHNDANIEL1]

@@QUIX4U Almost on my 28th month running over 900 amps start peak flow, 400 continuous and my designed cable resistance effect is @peak pulling 75% from the lead acid and 25% from the Lithium then when the high start load ends they balance in a matter of minutes. No wire heat happens or failures of BMS has happen as I was constantly told would happen. My lead acid water use is less than half it should be, their DOD is never seeing 50%, and the lithium/lead has performed just identical as the USN submariner electrical handbook said 2 chemistries should and would ( SLA and NiCad 1982 Section 4-8b )

[@juliancouch5891]

@@QUIX4U Thankyou for your very informative reply. The water analogy applies to the solar panel on the roof. The inverter senses the mains pressure and uplifts slightly to either supplement or overcome the mains. However in the battery connections, you will not have a zero resistance bus bar and thus slightly different voltages at each battery connection on charging and discharging. Is that not a problem over the long term?

[@montanadan2524]

Montana Dan the eletronics engineer says your description is close enough to fact that no corrections are required - good job.

[@waldolemmer]

Speaking in the third person is kinda weird

[@laus9953]

​@@waldolemmeryea, sounds a bit narc

[@powershot9933]

Seems sus. 🤖

[@grumpyoleman6608]

@@waldolemmerlmao

[@tandemkayaker]

If we assume that we get full capacity (or 90% of it) the BMS in the larger battery with its 250A limit is actually the limiting factor for large current draws - not the smaller battery with its 100A limit (7:26 time stamp). The reason is that the large battery is 4.6X larger in capacity than the smaller battery and will provide a current that is 4.6X larger. So the smaller battery and its 100A limit would correspond to a 460A limit on the larger battery but it is only rated for 250A.

[@occamraiser]

really? You think that the 100Ah rating of a battery is indicative of a 100A current limit? Those two things are absolutely NOT the same.

[@tandemkayaker]

@@occamraiser Did you watch the video? He days that the smaller battery has a max BMS output of 100A and it has a capacity of 100Ah. This is NOT what my comment is about. The question is - which battry is the limiting factor for large currents.

[@ecospider5]

Get the batteries within 1/10th of a volt before connecting them in parallel.

[@bobbygetsbanned6049]

That's totally unnecessary, they will balance each other once connected in parallel. You just don't want a big enough voltage difference that any of the batteries could charge or discharge too quickly when connected.

[@ecospider5]

@bobbygetsbanned6049 I agree. And that is what I do when building packs with raw cells. Putting a 3.5v cell with a 3.7 volt cell is not going to cause a lot of amperage between them. But a 4.1V cell and 3.9v cell could cause some inappropriate current. So for people that know that they’re good. For people that don’t I just tell them to manually balance to 0.1 volts. It’s the safest way to give instructions on that in my mind.

[@herbertcharles8606]

Should you not mention that booth batteries be at the same voltage before you hook them up to stop a surge of power from the highest voltage to the lower voltage battery.

[@comancheflyer4903]

He did.

[@vadnegru]

Essentially, this is what active balancers doing

[@ecospider5]

Extremely important to say again. Make sure the current voltage of each battery is within 1/10th of a volt or you might overload one of your batteries.

​@@vadnegru even low drop shottky diodes should help in some cases, like low power long term load.

[@ronnjerremy5796]

As long as you have power coming in periodically its not an issue especially with lithium rig with a BMS

[@leeinwis]

I got scared !

[@theredstormer8078]

After using jumper boxes this is kinda what I expected. Thanks for clarifying!

[@HughCStevenson1]

It would be a good idea to check that the voltages are similar before connecting them - you could get a big current!

[@ReeWrayOutdoors]

Check out my Part 2 on this video. I actually test that very scenario. At least with LFP, not really an issue.

[@bignicebear2428]

Wonder how many amps are going between the batteries when they equalize? If they are not both fully charged, could it damage the battery with the lower voltage?

[@daves2433]

Yes, he should have explained that. If one battery was a higher voltage than the other when first connected there would be a large amount of current from the higher to the lower voltage battery. Make sure to match the battery voltage before connecting them together. To be safest, attach them together with a resistor or lamp and allow them to equalize before attaching a wire directly between them. This would also be the case when discharged and one of the BMS' disconnects the battery. Re-balance the voltage before reconnecting.

[@nickwinn7812]

Yes, possibly, but the BMS should prevent a damaging current either entering or leaving both batteries.

[@daves2433]

@@nickwinn7812 This is only if there's a MS between the batteries. If they are directly connected to each other there is no protection... besides the wire

[@douglasjarvi9803]

Hell, I learned that in high school electronics back in the 70's!!

[@davebean2886]

Does it follow for maintaining the charge of same voltage, but different ah batteries that are not in service over an extended time in parallel? If the batteries are a different chemistry, does it matter for maintaining if the not in service batteries are fully charged to start? Thanks

[@stevengoodwin4501]

I have a "6 pack" of 2.4 volt Lithium Titanate batteries that store 12.6 volts for 40 Ah, tied to a Lithium Iron/ 100Ah. (with BMS). They are supplying power to 5 exterior 12 volt/ 2 watt lights, and 2 -2 watt bulbs (for half of the night interior lighting). I wake up in the morning to a charge reading of 12.8 to 13 volts EVERY MORNING!

[@TanPanama-k4u]

The bigger capacity battery will charge the lower capacity as well as provide external power. Then, when the capacity becomes the same, they both will charge external load until depleted.

[@stighenningjohansen]

The smaller battery will deliver power in paralell to the larger one, and will draw power from the largest one in pralell with the load, so it balances out.

[@SVAdAstra]

To expand a little on your point about BMS capacity ratings. If you were pulling a high load, say 150 amps in your demonstration, and the 460 AH battery BMS went into low voltage shutdown first, that entire 150 amp load would be shifted to the the 100 AH battery, exceeding its current specification limit. Because BMS limit shutdowns cannot be predicted and will never be exactly simultaneous, the rule I follow with parallel batteries is this: never charge or discharge at a rate that exceeds a single (or the smallest in dissimilar capacity configurations) battery's limits. There are also eddie current (balancing currents flowing between the batteries) considerations that occur when charging is terminated, so I fuse every battery at its terminals according to each battery's rating. I use MRBF fuses. I've never had one of those terminal fuses blow, but there are failure scenarios where they could.

[@alaska-bornfloridaman]

This is what I'm curious about. I'm trying to connect two 170 amp hour renogy lithium batteries and one different brand 280 amp hour lithium battery to a 3000 w inverter. Should I use fuses in between each battery and different cable sizes?

[@QUIX4U]

In "no" particular order, neither battery - will totally deplete itself before the other one starts to take the load, because THEY ARE NOT individually switched, via contactors or relays, thus BOTH share the load, reducing only in voltage as they deplete, when the voltage is about 11.5V BOTH batteries will have depleted to about 20% remaining (completely irrespective of capacities), as NEITHER simply provides all the loa current, until the battery's capacity is depleted - leaving the other with a "higher volage and remaining Ahrs. They are "after all" connected together. Same goes for two as for a hundred or more, of the SAME VOLTAGE but different types and ratings.. as ALL different capacity batteries would simply be "extra storage" at the same voltage (below I compare these with see-through water tanks with the same upper water levels) which would all deplete at exactly the "same levels" when interconnected as parrallels, because when each shares the total load - no battery will be individually depleting itself, before any other. THINK and respct the equation. BOTH batteries are comparible with TWO (or more) tall & "same height" see-through plastic water containers that could be connected together irrespective of capacity, thus a 1L container 1M high could be parralled to an IBC which is 1,000 L and 1M tall interconnected at or above the upper level of each (or 1,000,000 such tanks of various capacity, all 1M high) such that their lowest output vent, is at the same lower level as the other's lowest output vent. FILLING BOTH (or all) water containers to the SAME upper level, and then "opening" the one combined output supply pipe at their lower vents, ONLY reduces the total "level" as the load draws content (either water or electricity) from whichever "parralled" connection you have. The batteries will drain in EXACTLY the same way as the two interconnected water containers, it's just that the see-through tanks let you SEE what the dimishing current levels would be like, inside the enclosed (non-viewable) batteries.. NEITHER (OR NONE) of any interconnected battery, EVER depletes more rapidly than any other. Thus the BATTERIES would go below 1% capacity - at EXACTLY the same time. Neither (or none if more than two) would be "left" with any higher capacity level than their interconnected total "loading" capability levels, as BOTH (all) drain equally as the levels reduce. Anyone thinking otherwise, has ZERO idea what a "parralleled battery circuit" does, when any loads are connected to the one output point..

[@devious17]

I learned something here, thanks.

[@suatkaleli5075]

Hi! we have two batteries (12V 400A and 12V 100A) parallel connected and the load is 12V 100A. So when the batteries would not feed the load? Less than 1 hour or it would be about less then total current amount / load current?(100 + 400 / 100 = 5 hours) - Thanks

[@williamcrowley5506]

So I can add a couple larger battle born batteries to my current 400ah setup, excellent 😊

[@QUIX4U]

Make sure to read the existing battery/s voltage/s and ensure that the NEW batteries (to be added) are at exactly (or within 0.5% of) that reading - when connecting them in, or you could become "the cable" that makes the shorting circuit, resulting in a nasty jolt between fingers, or worse, across your shoulders (and critical internal organs).

[@astroreyes2535]

Very informative Video .. thanks for sharing Sir new follower from Philippines ♥️

[@phillpauley6672]

All I heard was the auto start stop battery on newer vehicles can be bypassed with a slightly stronger CCA battery. Or am I missing something?

[@raloed.363]

So what if the batteries have no built in BMS ? Like if you just connact the raw battery terminals in parralel? If one battery drops in volatge too much wont the other battery starts to charge it? Wont this increase losses in power due to the power loss during charging. Instead of battery power going directly to the output inverter. This wont matter much with small capacity but when dealling with 10s of killowats the loss can add up to be significant.

[@WorldOfWonder66]

Thank you for doing this video. With all of that being said how long were you able to run the heater in real time?

[@0neTwo3]

I have a van main battery under the hood. I have a small winch in the back for motorcycle loading. Currently I use a separate battery for the winch. Could I run a wire from the main battery to the winch battery for charging purposes? Would the amp draw of the winch fry the wires connecting the batteries? Basically looking for a work-around for running a big fat expensive wire from the engine bay to the back of the van.

[@P_RO_]

You'd fry the wire running the winch if the rear battery couldn't handle the load. Same if it drew too much charging current. In old RV's there was a "battery isolator" which allowed charging of 2 batteries, then disconnected the engine starting battery when you turned the engine off. Get one of those and your system should work OK. According to your wire run lengths and routing, you might be able to use cheap car jumper cables split in two. Just remember that the insulation isn't very heat or chemical (oil) resistant and the wire gauge may be a size smaller than stated. I don't know why the wire is so much cheaper this way but I've been doing exactly that to get power to the back of my workvans for over 30 years and never a problem of any kind.

[@jam5158]

Good info to know. I currently have a 200 AH lithium battery in my RV and was going to add a 100 AH to it but was not sure how this would work. Will my converter charge both batteries to 100% if it detects the 100 AH battery at full while the 200 AH has not been fully charged?

[@evilroyslade3155]

Just as noted in the next comment, you didn't mention that the capacities are additive when wired in parallel. Exceeding the discharge rate of the smaller battery isn't an issue when wired this way.

[@MYCHANNELWITHMYSTUFF]

If you hook up in parallel 2 of the mini's does the discharge rate double also from 100 amps to 200amps?

[@ReeWrayOutdoors]

@MYCHANNELWITHMYSTUFF yes...total output would be 200A

[@Youtuber-k2p]

It’s confusing when you swap between using amp hours and watt hours 2:35 . Simplify it and stick to one term, the one on the batteries, amp hours. Instead of 7000 something watt hours we can immediately see 460 + 100 = 560 amp hours as that’s what’s written on the batts.

[@Slackware1995]

He does that because the kill-a-watt meter reports in wh not ah. Even if the meter reported in ah it would be based on 120Vac not 12Vdc. This would be even more confusing as he would need to convert the AC side to wh and then convert from wh to ah for the 12Vdc side.

[@SOLAR-cr5dp]

Watt-hours are actually more convenient as energy is measured in kWh (“units”). Simply do an Ohm’s Law calculation to convert, e.g. 100 Ah at 51.2V use P=V*I ( 51.2 * 100) = 5120 Wh (or 5.12 kWh). Do the reverse to ge Ah.

[@adamrubinger2644]

One thing I've heard and please tell if I'm wrong is an issue with charging using highly electronically controlled or digital type chargers or charging systems that measure capacity. It was stated that this type of charging would essentially turn off the charge rate when the smaller battery gets to full capacity. In this system with a 100ah battery and a 450ah battery would only come to a "full charge" of only 200ah and would then not give the 450ah battery the additional 350ah of charge. I have not tested this myself so I honestly have no idea. The argument does make sense but again please tell me if I'm wrong. Thanks!

[@Out_of-_Box_Thinker]

Most of the charge current would flow into the larger capacity battery,, so the SOC of both batteries would rise to 100% in sync with each other.

[@Constant_Distant_Instant]

*So in short, this is a no go area just to be on the safe side!*

[@curtbrown9702]

On a boat. Solar charging in day, wind turbine charge at nite, seperate mppt controls, if day time and windy can i use both at one time ? Frig, stove and or anything needed that does not go over inverter capacity to KEEP batteries up. AC unit . There for not needing to run generator for periods of high needs. During day, solar, nite hopefully wind to run frig, AC. Can i run both at one time to KEEP the batteries up?

[@Ben1551]

Yeah you can, it just looks like extra charge current to the batteries, You could run solar, wind, generator all at the same time. Go make some power! enjoy the boating

[@curtbrown9702]

@@Ben1551 THANK YOU.

[@imageinphoto]

One other possible concern is if one battery has an internal heater and the other one doesn't. I have two 100ah batteries in parallel in one bank inside my RV trailer and a 300ah battery with an internal heater outside in a storage box. The two battery banks are connected by an A / B / Both switch. During storage I keep shore power on the trailer, but, set the A / B / Both switch to the 300ah internal heater battery only. That way if I lose power the 300ah battery doesn't try and use the two 100ah batteries to run it's internal heater. I haven't actually tested if it would. During useI run all the A / B / Both switch set to Both. During a recent trip on a particularly cold night I did seem to have an accelerated capacity drop so it might have been the case. So any future cold nights I switched to just using the 300ah battery and then only recombined them after I had shore power and could top off both banks.

[@mrracerx8302]

Thank you

[@robertrice4441]

Since both batteries are discharging percentage wise equally, does that mean the larger battery is contributing approximately 4 times the current at any given time compared to the smaller battery?

[@Sylvan_dB]

That's the general idea. The exact ratio is going to be determined by the internal resistance (IR) of each battery as well as the cable and connection resistances. IR varies with state of charge and the rate at which it varies is going to be different battery to battery (closest in batteries off the same production line with the same batch of materials, etc). The great thing about parallel is it doesn't have to match exactly, but can trade off a little bit and if given time to rest the batteries will equalize if the difference is significant. Unless they are grossly different (or cabling problems) the higher state of charge will supply more current to the load while the lower state of charge will take more current when charging.

[@RexxSchneider]

@@Sylvan_dB Indeed. This is especially true with Li batteries whose output voltage tends to correlate quite well with the state of charge. It may not work so well with batteries such as NiCd whose output voltage tends to remain constant until it drops off rapidly when the battery is exhausted.

[@laus9953]

​@@Sylvan_dB people should be aware that for such 'cabling problems' as you mention, there should be enough fuses between the parallel batteries

[@seddiqullahkhaliqi5916]

in case of planning to have 12v, then nothing to be worry about ?

[@occamraiser]

Nice to see that the real world actually matches what we were taught at school. :) I'm working on the assumption that a bank of lead-acid batteries will achieve the same - although I don't think that they deliver as much as 90% of their rated capacity.

[@keithmcdonnell4485]

Question for you, I have 4 12V 75ah batteries that were originally configured as a 48V series connected pack for an electric riding mower. They were replaced because one battery was weak. I currently am using the 3 good batteries in a 12V parallel pack with an inverter to run essential loads during power outages. Could I add the 4th "weak" battery to my setup for increased capacity?

[@wernerviehhauser94]

Works just fine in parallel. Just basic physics. They will always be the the same voltage, and during discharge they will just share the current according to their internal resistances (server power supplies share loads in a similar way, look up droop mode). The BMS is of no consequence here, since the smaller battery should never see the larger current - and if the 250A BMS shuts down for whatever reason, the 100A BMS has a very good reason to do the same. You might just want to keep the smaller batteries at the far end of the wire connection, since the little resistance in the wires will cause the front battery to see a larger voltage drop, and if the small battery is in front, some high inrush current might trigger the smaller BMS. In series, connecting two batteries with different voltages but EQUAL capacity is possible, but it is very rarely done.

[@corcorandm]

Thanks for posting the video. Cool test and good points about the different discharge ratings. 1 question and one concern: If they were providing a total 300A load, wouldn't they split the load according to... Some other factor? (Internal resistance maybe?) The concern I have in this scenario is charging and reduced performance long term. The CV,CC charging stages of each battery are likely reached at different times. In that case it might be best to customize or limit the charging profile, likely resulting in lower total capacity.

[@JamesAmbrose48]

It’s probably not a good idea to use this combination for high discharge applications like the 300 amps you described. This would be for slow discharge application. For high amperage uses, both batteries should have the same size BMS so the load can be equally bifurcated between them.

[@Sylvan_dB]

Charging isn't a special concern. You are thinking correctly when wondering about how they split the load, the same logic applies to charging. As for how they split, internal resistance is an issue, but usually a bigger issue, especially with LiFePO4, is the cable and connection resistance. You can test this using a clamp meter to monitor the current in the different wires between the batteries and battery to load/charger. With very different batteries such as in this video, internal resistance will definitely help split the current. That said, you would never want to do this with any load (or charger) close to the maximum supported by the total of the batteries. The current is not going to divide that precisely and it will change depending on the state of charge as the internal resistance curves of the batteries will vary. Beyond a quick surge the imbalance is likely to trip a BMS if operating without enough margin. If using two matched batteries, I'd probably be comfortable with designing for 75% of the total current (i.e. batteries support 2x 100amp, I'd probably be okay planning a 150amp max load). Note how that means even a gross imbalance of 2:1 is within the specification for a single battery. Using a setup like that should be fine. The more batteries or the more different the batteries the more safety margin is required.

[@ReeWrayOutdoors]

@@Sylvan_dB Very nicely described!

[@walsakaluk1584]

Kirchoff had a bit to say about this. The community here would garner a more intuitive understanding and develop a deeper understanding if they studied Kirchoff's and Thevenin's laws. The penny will drop once these are understood and will have these folks designing systems on beer coasters and napkins in no time.....and get it right without assumptions or vague personal models of what's happening. If you connected these batteries in parallel via a busbar with separate tails in parallel, you could measure how much each battery was contributing and see how the larger capacity battery is actually charging the smaller one during periods of the discharge. That was a nice Heath Robinson style demo.

[@Sylvan_dB]

@@walsakaluk1584 Once I stepped out of the classroom into the lab I realized that while Kirchoff, Thevenin, Norton and others provide a brilliant theoretical framework, the real world requires a lot of assumptions and rules of thumb. The first problem encountered is an almost complete lack of specifications necessary to perform the requisite calculations. The second is that we must design for the center and avoid edge cases because of individual component and environmental variance, so the additional analysis is seldom useful. Oh well, the theory does provide some direction in thinking even if the equations are never evaluated.

[@clifforddicarlo9178]

Discuss the different internal resistances between the Larger Capacity battery and Smaller Capacity battery.

[@warth-media]

This is interesting. I was trying to figure this out, and your video gave me an idea for my problem. I have a UPS with two 12V batteries in series to create 24 volts. Obviously, I can't mix and match batteries in this case, but what I can do in the future is purchase 24V batteries instead. If I wanted to increase capacity, I can just buy another 24V battery and connected it in parallel. Is this correct, or am I missing something?

[@abuxxx3607]

You should have measure the Amps each battery draws while being loaded to show different current draw from individual batteries.

[@ReeWrayOutdoors]

Yeah, I actually did that in the 'Part 2' follow-up on this video. 👍

Gotta be careful tho if the wear is different, as they will try to equalize and the strongest battery will constantly try to pull up the weakest one. What i usually do as a test is charge both batteries together, let them equalize, then disconnect from the charging source and check with the ammeter if there is significant load transfer between them over time. It's a problem really only if it's there's no external charge for a long time. Like i had a weather station pulling only 10W and needing to last as long as possible between charges, so i decided to put as many lead-acid battery i could in parallel, the last one i added was supposed to give me roughly 40Ah more, but ended up giving me only 5Ah at best on the long run and wearing out other batteries faster in constant equalizing, so i pulled it out. Great video tho.

[@ranger178]

can i charge a lithium-ion battery in my boat with a small solar panel to keep it charged to run the sump pump if it rains

[@MonkPetite]

Try this with agm batteries with out internal bms. The capacity is there but the cycles are less . Basically different size battery’s with out bms do not work well for the longer duration

[@laus9953]

reason?

[@MonkPetite]

@@laus9953 good you ask. It’s my experience on several vessels where Victron agm battery’s where installed ,different sizes liked together. In most cases the bigger battery does not get absorbing time. The battery’s doe not equalise at all. On the battery monitor systems it looks well. But apparently the life cycles are about 60% of a normal span.

[@richardleonard2946]

Interesting video. Could you please expand on the reasons for not mixing battery chemistries? I'm guessing it becomes an issue at high current draw rather that lower but I really have no idea. Thank you.

[@mro2352]

Just guessing but I think the discharge curve would be different causing overcharging wear on the less energy dense chemistry.

[@bowlampar]

You can do it personally don't always mean that it is advisable to do it against manufacturer instruction。🤷‍♂🤷‍♂

[@HughCStevenson1]

Manufacturers will not usually instruct against this if the technology is the same for the two batteries - same maximum charge voltage, same discharge curve, same end voltage on discharge. If they do it is probably the legal department overruling the engineering department! It will work very well, has been done for decades.

[@scooter6334]

Enjoyed the advice. I bought 260ah 2x and now I have found 280ah 2x for less. Same brand of batteries. Now my question is what would this do to my Victron shunt reading? 🤔 I am running in parallel, 12v.

[@ReeWrayOutdoors]

@scooter6334 shouldn't do anything really. Just need to reset the new Ah capacity total and probably recalibrate to 100% and you should be good.

[@scooter6334]

@@ReeWrayOutdoors Thanks so much for the feedback. Would you set the shunt to the 260ah or the 280ah?

[@angacamthehobbit-PapaPrepper]

Simple question: How big a parallel bank of LIFEPO can you build? Yeah, the manual says 4 batts, but can you go 5,6,7,8, etc etc. As you said you can add as your budget increaes.. Thanks

[@davidpatrick1813]

Tnx. I wonder if you did pull more than 100 Ah ... why wouldn't the higher amp hour battery try to equalize and the current that is needed would use the cables to pass. I could see maybe too small of cable .. might be an issue... It might be an interesting test. If the BMS shuts it off then you can restart it anyway.

[@KevinCoop1]

It would be nice to know how many amps each battery was discharging at.

[@honeydavis5568]

If you know what you are doing you can do anything you want. If you don't, then you can get into trouble no matter what.

[@ecospider5]

I do anything I want. And I definitely don’t know what I’m doing. 😂🤣😁

[@QUIX4U]

@@ecospider5 It's only that you get results you never expected, so lets hope the next one doesn't kill you (as not knowing what will happen when doing dngerous things - will ALWAYS end badly).

[@ecospider5]

@QUIX4U I really enjoy setting something up in a crazy way. Then seeing what happens. The trick is understanding how crazy the setup is so you know what safety procedures to use. Like plugging in a 40 year old amplifier that hasn’t turned on in decades. Don’t do that with 120v. Get a thermal camera and watch the electronics as you increase the voltage starting at 30v. A damaged component will probably heat up too early. Doing it at a low voltage stopped that component from damaging others. Something that surprised me the other day was a fire extinguisher. I had an expired on so discharged it in the yard. If that was in a 12x12 room I would not be able to see for 5 minutes. I do crazy things when it’s safe that way I have more knowledge of what I can do safely in an emergency

[@FlorinSutu]

Usually, the batteries do not have exactly the same potential at each of the 2 poles. When they have no load, but they are in parallel, regardless of the capacity of each battery, there will current from one (+) to the other (+), and from one ( _ ) to the other ( _ ), until they equalize. Only the potential difference matters, the power drain may be from the small battery to the bigger battery.

[@actionjksn]

That was good information and I'm frankly not surprised by the results. I agree with your conclusions, but I suspect that a good number of people will not agree.

[@Bizmyurt]

As the currents add up the difference of capacity is not to big of an issue. If you have 100A from one and 250A from the other the total will be 350A.

[@jhunriecutad5289]

What happen when you parallel old and new battery?

[@JohnDoe-md2sb]

Is it acceptable to connect a small 12v sealed UPS battery with a 12v automotive battery in parallel?I'd be using a Noco smart charger?

[@genehart261]

This might work short term but if you parallel two lead acid batteries of different age or capacity for any length of time they will "fight" each other until they both fail. Personal experience.

[@valvio1331]

hence, you use batteries with similar age/capacity. ;)

[@thatairplaneguy]

I form lead acid batteries and you are correct.

[@HughCStevenson1]

I used to design battery management systems and chargers for telecommunications installations. Lead acid batteries of the same technology are frequently connected in parallel. So long as the state of charge to Voltage relationship is the same for the two (or more) batteries they will share and not be damaged. The charger should ensure that both reach the end voltage when charging and are disconnected before being over discharged. These voltages are the same for new or old batteries of the same technology. This is true for Lithium batteries as well. I don't think they can "fight" each other - what would that mean in terms of voltage and current? And they certainly do not fail - they can last decades. On the other hand, similar age, technology and capacity is critically important for series connection.

[@AySz88]

​​​​@@HughCStevenson1My guess (from the very little information, admittedly) is that one/some had significantly more equivalent series resistance, so that the effective voltages are mismatched every time the load changes or charging state flips. (This would happen a lot more often for, say, buffering solar energy than for battery backup for grid power.) I wish ESR were easier to measure to avoid such things.

[@zerdgeofficial]

They try to charge eachother if one has different capacity and this process heats the batteries up until they explode

[@oldmanebikes8392]

From what I understand is when you connect them in parallel the bms in both combine so you could say run something that uses 350a continuous so maybe ck that out next and try to run say 250a thru them and I don't think the smaller one will shut off. I been told they would share the load and the smaller one could handle it so let me see you try that next. At least try to run something larger than 100a and see if it shuts down the bms in the smaller battery. We do this with Ebikes and I haven't heard of any that shut down

[@RexxSchneider]

No, the BMS systems don't "combine". The ratio of the capacities determines, to a first order approximation, the ratio of the currents supplied, so the smaller battery supplies 18% of the total current and the larger one supplies 82% (i.e. 4.6x as much). Since the large battery's BMS limits its maximum current to 250A while the smaller battery's BMS limits its output to 100A, the larger battery's BMS turns out to be the limiting factor (only 2.5x that of the smaller battery). The result is that with a total current draw of 300A, the larger battery would supply 246A and the smaller one would supply 54A. Any more and the larger battery's BMS would trip, immediately followed by the smaller battery's BMS as it tries to supply the full 300A+. So the maximum current you could expect to draw from the system is around 300A.

[@nickbengtsson6518]

Many thanks for this demo. Just one question, is it ok to connect in parallel 2 batteries one having cylindrical cells and one having prismatic ? all the best from the UK

[@HA05GER]

This is essentially how solar eystems work all down the voltage on wether your home consumes from the grid or the battery. These will essentially bqlance as the laod will draw from rhw device with the highest volrage.

[@mudpuddle8805]

Does every LFP have a built in BMS? Do the Lead Acid batteries for these systems have any kind of BMS built in?

[@wa1gon]

Great video. I have 2 banks of 4 LiFePO4 batteries each bank is a different "brand". All 100 A/Hr. When I say different brand I mean the name on the battery is different. The BMS is Bluetooth enabled and both brands use the same app and the manual is the same except for a couple of pages added. So I think the OEM is the same. When I connected the banks in parallel the BMS reported much different current readings. I got concern so I disconnected one bank, but from the video it sounds like I shouldn't worry. Comments, suggestions.

[@tonysolar284]

Does it Self-Heat like the Self-Heating 100AH?

[@natewarner359]

Thank you Great Info

[@farhanredza]

Thank you!

[@hooligan9968]

Great info!! One question though! If you paralleled 2 batteries that were the same size one with Bluetooth and one without. Would the capacity from the Bluetooth battery now represent the entire bank?

[@ReeWrayOutdoors]

@hooligan9968 highly doubtful, since capacity readings (for LFP anyway) are typically done with a shunt that monitors Amps in/out. And that internal shunt is only going to measure the current on that one battery. You COULD add an external BT enabled shunt to the main negative and thereby see the total in/out current.

[@richardross3815]

lol…. Nice and simple. I like simple! Well done.

[@alexportiiii6414]

thanks!

[@manueltolentino361]

Why not isolate each battery using diode to supply a common load?

[@flutini1]

I'm sure this an apples vs oranges question (and will reveal my lack of knowledge on the subject) but what happens if you connect solar panels of different wattages in parallel to a battery bank (via a mppt charge controller, of course?)

[@tincanboat]

thanks great information.

[@TopperPenquin]

Metoo you are an Excellent Teacher

[@ReeWrayOutdoors]

@TopperPenquin thank you for kind words. Sincerely.

[@countmorbid3187]

Theoretically, if the small one has a 100A and the big one 200A and the voltages are the same, 200A load should be fine.

[@gaylanbishop1641]

Great demo, but I think it would be good to note, in the series arrangement, the capacities DO technically add, just as in parallel. The smaller unit will deplete quicker than the larger one, and will “open “ the circuit, as you said. Of course, you would never purchase such different batteries for such a use, but what if someone had a critical situation, needing more instantaneous capacity than the 460 AH battery could deliver on its own, in a 24V system, and the only other battery available was a 100 AH 12V battery. Connecting the two in series would provide extra capacity for the duration of the smaller unit’s charge, possibly providing the user critical time to get his battery situation outfitted properly. So since I can only picture someone doing this in a crucial situation, I thought this would be a good point to share. Thank you!

[@HughCStevenson1]

The voltages add, not the capacities (in A Hr). The series combo has the capacity of the smaller battery. Once it is discharged it will drop in voltage and start to be charged in -ve voltage which will damage it very quickly.

[@gaylanbishop1641]

@@HughCStevenson1 I disagree. The capacity doesn’t follow Thevenin’s rules. Capacities always add. While the smaller unit is “alive” the capacities of the two will add. The smaller one will likely discharge more quickly (although even that is dependent on the two batteries’ individual chemistries, starting charges, and environmental conditions). When one of the batteries completely discharges, it will likely present an “open” to the circuit and at that point they will sum to zero. But before that time, you will have the benefit of both their capacities, which,as I said, may help someone get through a serious situation until they can procure proper batteries.

[@HughCStevenson1]

@@gaylanbishop1641 You are absolutely correct that Thevenin equivalent is not applicable because we are not talking about linear components like resistors, capacitors or current/voltage sources. Perhaps a real example would help (I think we actually agree but are using different words...) Consider a 10 AH 12 V battery and a 20 AH 12 V battery. Both fully charged. We connect them in series and start discharging at 1 A. We have 24 V because the voltages add. After 10 hours the smaller battery is exhausted and we can't continue without damaging it by over-discharging. How much charge did we get? 1 A for 10 hours = 10 AH. So the effective capacity is the capacity of the smaller battery. The voltages add and the capacity is the capacity of the smaller battery.

[@gaylanbishop1641]

@@HughCStevenson1 Please don’t consider me as arguing, I’m looking at this as a discussion and I’m enjoying it. I hope you are too. I’m a retired electrical engineer and I don’t get to have these kinds of discussions too often. (I was actually disabled by getting into the high voltage terminals of a 12kV transformer…lost both my hands). So let’s go back to your example, with 1 amp in the circuit. Isn’t only a portion of that amp being produced by the small battery and a larger portion produced by the other? The way it is looking to me, yes, 1 amp is flowing through the small battery, but the chemical reaction inside it is only producing some fraction of that 1 amp, so it would take awhile longer to discharge. It’s apparent that you know what you’re talking about, so help me to clarify this in my mind. Thank you.

[@HughCStevenson1]

@@gaylanbishop1641 If the small and larger battery are in series the current in both must be the same. 1 Amp. You are thinking parallel...! I'm an EE too so enjoy talking about electricity!

[@arwinmaraham1277]

Sir could be possible if I want to make a parallel (12 v, 100ah x2) then I series it with 12v 200ah...in other term 12v 100ah x2 + 12v 200ah...thank in advance for feedback.... please help...

[@stevehoping7443]

Will this apply to lead acid batteries as well?