Using batteries with different capacities in series! Total balance chaos?

[@TrevorFraserAU]

The education in your channel is incredible. It amazes me how much misinformation is presented as fact, even from battery experts, and even more worrying, from local suppliers of some of the big battery names out there. Your testing clears it once and for all, and we can go from theories to happens in the real world. Please never stop educating us, and thank you for all you've done for the DIY community to date.

[@gumpster6]

I don't know how you can keep up with all this testing, but I'm enjoying watching it.

[@OffGridGarageAustralia]

I don't know either... but there is a lot more to come. Still so much to test, understand and share...

[@africanwildlifewaterhole6091]

"I'll switch the charger off, you watch the voltage" 😂😂😂

[@rainman1701]

That sleep mode is probably the reason the BMS has that small, on board battery. That battery is powering a minimal RTC circuit which keeps track of how long the BMS has been in sleep mode and wakes it up according to the resting delay/inspect time settings.

[@mozismobile]

I am liking this BMS a lot. It seems to have all the necessary features and they're decently available.

[@OffGridGarageAustralia]

Yep, it is pretty good. I'll do a final review and verdict in the next video

[@carmichaelmoritz8662]

Don't forget that without the neeeeeeey bms it wouldn't work so good.

[@CantFindInYoutube]

6 years to balance :) love it. I start to test my batteries every 3 months, and each time I agree more with you, top balance should be done at high voltage, during winter I had 3.25V and global capacity start to go down, I do a full cycle every day and even with the JK BMS that should balance at 2A, over 8 hours I only had a small change in delta, I use grade A cells. Only manage to go over 3.6V if I charge at 500mA, higher current cut charge with over-voltage. Would like to see a BMS that has a lower and higher voltage to balance with at least true 5A to see if we could get more juice from cells. I know that it's not important, those values are less then 3% of cell capacity but with degradation over the cycles and years could make a difference. Your Frankestein project for me is a travel in time for what we will have when some cells start to deviate. Congrats for the good work.

[@OffGridGarageAustralia]

Thanks a lot for your feedback, Miguel. I was hoping for some interesting results when building the Frankenstein Battery. It really behaves like an older battery were some cells are degraded more than others. The low balancing is always problematic and shifts a lot of energy across the cells, causing more wear. I have a 15A balancer here to test this out... so watch this space...

[@FutureSystem738]

The weak point with the JK (and most others) is that it can only work on two cells at any one time, ie: one high and one low. (This is where the Neeey really shines.) This also means that as the number of cells rises, the BMS’s ability to balance unfortunately becomes less effective. I have a JK BMS now on my 4S caravan (12V) system, and with only four cells, it works really well.

[@CantFindInYoutube]

@@FutureSystem738 You have a point and it work for the propose that was designed a system like yours. In my case I do half a cycle in summer and full in dark days, 2A in a 280Ah is 0,007% there are 15A balancers but they cost 3x the price of an BMS and only 0,054 %. Anycase if cells are in good shape we are fine. In a few years in the future we should have better balancers when they degrade.

[@wayne8113]

Thanks Andy

[@whatmust8146]

Yep i agree because i had 100 of 18650 cells to build up 100p pack all from recycle laptop batteries so in my case that is the worst scenario of 14s100p all from used small lithium cells. With such severe mismatched in capacities and impedances the pack still worked for years and years so with the LFP in 200+ AH capacity the mismatched is minute in contrast with mine. Many people do not know because they don't play with the worst case scenario like i did and still do. Well all can benefit from real life example so I can say with certainty that any mismatched of LFP from capacity to impedance will work just fine for years and years PROVIDING an active balance is used. The pro of build and use from the 18650 cells is that it gives one tremendous knowledge and experience. The LFP is a piece of cake to understand once one plays with the former small lithium cells. I am in the process of migration to LFP new and used cells and perhaps the server rack type. I find that build yourself is WAY WAY cheaper and i can pick and choose the type of battery and bms i want to use and i can fix myself easily if it breaks down. It all depends on your level of knowledge and willing to do. Ready to go system : higher cost,?????????quality of components, not able to fix if break down DIY: lower cost, more bang for the bucks, battery and bms and misc. choice, fix yourself as DIY teaches you a bunch of how the whole thing works!!!!!!!!! EV hobby is a very fun and rewarding activity. There is NOT a day any of us not using electricity.

[@laurentsantaibambu7324]

Hi Andy,and thanks again for,this video..

[@OffGridGarageAustralia]

No problem, thank you.

[@sarahjrandomnumbers]

So if there's a solar farm next to you, surely you could ask them for a tour and have a chat about the difficulties in running a massive solar farm? That'd be such a cool video :)

[@freddytv2208]

Is there a DIY kit like the Seplos Mason 280Ah with this GobelPower BMS without included cells? Only the empty case with the BMS.

[@OffGridGarageAustralia]

Nope, I've asked Gobel for that but they only sell the BMS or pre-assembled batteries with this BMS. I'll ask again 😊

[@hendersonsobers396]

Hi Andy, looks like to Gobel BMS is working out quite nicely. The Gobel BMS seems to have an extreme amount of features...most of them useful but some not so much. I see that QUCC and JBD has similar variants of the Gobel also. Great video as usual I've learnt so much from this channel- thank you Andy.

[@OffGridGarageAustralia]

Yeah, the GobelPower BMS is by far the best I have tested here on the channel. The amount of settings and options is great but can be too much at the same time. Luckily everything can be configured. I have seen the BMS from QUCC and JBD. Just not sure what software they are using. All these BMSes are very similar from a hardware perspective but the software is wildly different. And this is what makes all the difference.

[@hendersonsobers396]

@@OffGridGarageAustralia I've also even seen Daly BMS on YT which apparently (according to Daly) can now communicate natively with a number of big brand inverters. If this is the case, that'll be great given that they have BMS models that can do up to 500A. I know you're not a big fan of the Daly Andy :)

[@OffGridGarageAustralia]

@@hendersonsobers396 a DALY 😂😂

[@hendersonsobers396]

@@OffGridGarageAustralia lol

[@carmichaelmoritz8662]

Don't forget that without the neeeeeeey bms it wouldn't work so good.

[@danielardelian2]

I used to have a 16x 100Ah pack of Winston cells in hard ribbed yellow plastic cases. It cost a fortune, back then. Those cells had less than 5 mV imbalance at 100%, on nearly every charge cycle, after an initial top-balancing (by charging them all in parallel up to 3.65V). Now I have 16x 280Ah EVE "Aliexpress grade" cells and these have about 40 mV imbalance at the end of every charge cycle...but a JK-BMS with 2A balance current keeps things well under control, no cell has triggered the Cell High-Voltage Disconnect or the Cell Low-Voltage Disconnect of the BMS...

[@OffGridGarageAustralia]

Yeah, the good old Winston cells... I heard nothing but good from these expensive bricks.

[@binauchich]

As we have seen with the big shelf, the voltage is the leader, the current is self adjusting. The weaker battery pack supply the lower current, the voltage is same. Pitty that they didn´t invest in a better balancing performance.

[@OffGridGarageAustralia]

If it would have a 2A active balancer... man, that would be almost like 🐸🐸🐸🐸🐸

[@carmichaelmoritz8662]

I'm thinking about trying those neeeeeey bms. 👍🤟👌. your wife says your backyard looks like a solar farm , my girlfriend says my farm looks like a poor farm 🤣😂🤣

[@innocenzoiannilli5536]

Very interesting "Frank battery" 👍👏Rome Italy.

[@ForgottenGamesAndMods]

I would really like to test what happens when putting LiFePo4s in parallel with classic SLAs. From a general perspective there should be a great advantage exactly when it's needed: when LiFePo4s are near depletion. That's when the SLA comes in and offers good sustainability taking on most of the current. From a math p.o.v. Charging the LiFePo4s up to anything between 3.45/cell and 3.65/cell should keep up the SLA high enough (did the math for 48V 16s//4s). The problems could be the following: 1. When on no charge/idle mode and during discharge cycle how much of the LiFePo4s would go towards SLA as float/compensation ? 2. How fast would the SLA voltage drop when discharging starts ? SLA starts draining a lot of current after a specific charge point. Is that sustainable ? LiFePo4's nominal corresponds with SLA's charged idle voltage, while LiFePo4's idle charged stabile voltage corresponds to SLA's float. This needs an over-time analysis. I will try to setup a small scale test once I have everything needed. But any testing with 100Ah LiFePo4s alongside 50-100Ah SLAs would be the most relevant. What do you think ?

[@OffGridGarageAustralia]

I don't see any advantage. Lithium is far better in any aspect. If your lithium battery is depleted, get another one in parallel. If you still have lead acid batteries, yes, you can use them but it has absolutely no benefit or advantage of using both or even buying lead acid to parallel them with Lithium. One channels on KZbin want to make people believe it's the best of both worlds, but it is not. It's in fact the opposite. And charging voltages for Lead Acid don't work well with LiFePO4 in terms of Equalization for example.

[@ForgottenGamesAndMods]

@@OffGridGarageAustralia Thanks for the feedback. I'll just use SLAs for UPSes instead, but still, I'll make a small scale experiment since I'm curious of the results.

[@uhjyuff2095]

I appreciate you pointing out the balancer on the bms is reducing the cell deviation by 4 mv in the hours of the day. maybe a few days and you would notice more?

[@OffGridGarageAustralia]

Why would you keep the battery at such a high level just to give this under-dimensioned balancer of the BMS a chance to do its work... We have tested the Seplos BMS once and I left it for two days just to see the deviation didn't come down a bit. 40mA one a 280Ah battery is just not working.

[@uhjyuff2095]

@@OffGridGarageAustralia Check it out! The BMS balancer can be set to balance at 3.4 or 3.45 volts per cell so its no big deal to wait. When doing a specific task like balancing the cells, Set the bms over voltage parameter to 3.45 volts and the over voltage reconnect parameter to 3.39 volts and balancer turn on voltage at 3.4 and come back in a few days and the pack will be balanced or pretty close to balanced. If it needs a few more days the bms will get er done. Then after wards like you said you will be ready for the winter months and set the over voltage parameters back to 3.65 volts and its done! No need for adding an external balancer and all that jazz just a tweak of the settings a week before the winter months!

[@OffGridGarageAustralia]

@@uhjyuff2095 But this will not work on a daily base. Only if you do such a 'maintenance' period for a looooong time. I have done this with the Seplos BMS and let it sit there for 2 days. Didn't make a dent. The problem with this is that you need to keep a power supply turned on for that time so the voltage stays that high. This can only be for an initial top balance or a maintenance period. You cannot use the battery for that time for anything else. So I think for daily usage of a battery we need a bit of that balancing jazz...

[@ladams5356]

Andy I have a problem with 2 different capacity batteries ( same make ) where in order to get both to charge at .5C you have to set the BMS charge level at 1C levels in either of the BMS’s. The issue I have is protection for a fault I.e 1 battery fuse blows or mcb opens and in that scenario the remaining battery receives charge at 1C! I know it’s unlikely for a battery to disconnect ( but it’s BMS remains in communication) but it could happen. How can we fix this.

[@boatelectricaldiy]

I loved the concept of the Frankenstein battery. I'm finding it hard to pay attention though as this feels like a BMS infomercial series.

[@OffGridGarageAustralia]

I'm testing this BMS. Because it is good and I try to find some negative points as well. If not interested, why not come back later? We will soon be testing another one with this battery... Just saying, nobody needs to watch all the videos if one is not interested in this topic.

[@boatelectricaldiy]

@@OffGridGarageAustralia No offence meant, I was not having the best day when I made this comment. I understand a great portion of your audience really enjoys the new BMS testing. Take my comment with a grain of salt, I have a bms I am biased towards as I use it professionally, so bms reviews don't appeal to me. Keep up the good work, you make informative videos.

[@OffGridGarageAustralia]

@@boatelectricaldiy no problem, my friend. You're one of my long term subscribers and I appreciate all your comments! Thanks a lot for your support.

[@jabersaeed2731]

Is it possible to install a DC DC bulk converters as a chargers with constant 4.2 V for each cell in order to get them balanced ?

[@L0v4szL]

Hi Andy! I would like some advice. I am also making a 280ah Frankenstein battery, but due to lack of space, a house standing on the ground would be good. What do you think about vertical houses like seplos have? I am worried that the 8-8 cells in the two columns will deform the bottom one due to their weight....

[@micropower8]

Good information from you. Nice video! I like it. 🙂

[@OffGridGarageAustralia]

Thank you for the feedback.

[@alfredkennedy816]

I don’t have a battery management system for a 12 X 18650 battery. Would two laptop BMSs in parallel work?

[@billhunsinger862]

I have 2 Orions 30Amp in parallel feeding 3 RB100s with a house charger and Alternator on a boat. I put in same parameters but they go into a cycling mode every 5 seconds of engaging then shutting down. It once went to a steady charging to bulk mode once after about a minute. Is this normal? Should Adaptive Absorption mode be turned off? They will not turn on with the house charger when Engine Detection is on.

[@GeoffHou]

Thanks for the info. Would like to order some batteries. Would you still recommend QSO that refer to 3500+ cycles or to go direct to EVE which mentions 6000 cycles. I would start with 16 batteries but that could potentially grow a lot.

[@matija3791]

08:00 the internal resistance of the cells is different, so the Ah per cell will never perfectly match at 55Ah for all cells as the losses per cell is different.

[@OffGridGarageAustralia]

Ah will be the same for each cell because the current is the same for all cells. Just the energy charged is different due to different heat loss.

[@Dutch_off_grid_homesteading]

Heya, oke it needs some balancing but which battery doesn't need that

[@RobertManz]

Hi Andy, das scheint ja wirklich ein großartiges BMS zu sein. Nur eine Info habe ich bisher nicht gefunden: kann ich auch mehrere BMS miteinander verbinden um dann bspw. 3 Batterien mit 3 BMS mit dem cerbo zu verbinden? Wenn das ginge würde ich sofort bestellen. Vielleicht kannst du mir da weiterhelfen ?

[@OffGridGarageAustralia]

Up to 32 BMS can be paralleled together. No problem... The final verdict about the BMS will come in the next video. But, it is really great! Don't forget to use my referral link if you order to support the channel: off-grid-garage.com/battery-management-systems-bms/

[@nunyabusiness9760]

Andy, thanks so much for the updates on the Gobel BMS! Question: Do you think that maybe the balancer on the Gobel BMS is "fighting" the Neey balancer, by that I mean, is there a possibility that the BMS is shunting 40ma of balance current being supplied from the Neey that sees a particular cell as being low in the group (of 16 cells) while the BMS is simply triggering off of the defined balance start-voltage threshold? With the pack being so close saturation, I was a little surprised to see that the deviation didn't drop faster.

[@OffGridGarageAustralia]

Never seen balancers fighting against each other. Not even with different settings.

[@jameshancock]

I = v/r You ignored part of that in your explanation because in batteries resistance isn’t a constant. It’s variable based on voltage. Thus a battery at 3.1 will have lower voltage than one at 3.4 and visa versa. Thus the variation between capacities means you have a multi variant problem because of the voltage affecting the resistance. Thus every charge/discharge cycle will expand the delta without heavy balancing. And yes it will be way worse than if you use matched batteries. So you need more balancing power to make up for the difference. Doesn’t matter if you’re just doing too balancing and ignoring the extra capacity or not.

[@alfredkennedy816]

I don’t have a 12 X 18650 battery pack. Would two laptop BMSs work?

[@mozismobile]

not the same energy for a series discharge with varying cell voltage, only current. Small difference but important. You could even do this across chemistries if you wanted to make it even more obvious. In a theoretical world you could have 100Ah 1.2V NiCd cells in series with 100Ah 3-ish volt LFP cells and it would all be fine. In practice the top of the charge curve would be unnecessarily exciting.

[@OffGridGarageAustralia]

Yes, correct. Ah are the same but not energy due to difference in Ri and heat lose.

[@davidpenfold]

Hi, just as an aside, do you know where I can find the rubberish things to separate the batteries? I'm looking at creating a 30kWh battery with two sets of 16 batteries in parallel at the battery level with my REC SI BMS (rather than in parallel at the battey level). Thanks!

[@OffGridGarageAustralia]

Yes, it's on my website: (scroll a bit further down) off-grid-garage.com/electric-installation/

[@davidpenfold]

@@OffGridGarageAustralia Cheers. I've bought 8m of the 5mm sticky stuff 🙂

[@OffGridGarageAustralia]

@@davidpenfold 8m!!!!!!!!

[@davidpenfold]

@@OffGridGarageAustralia It's only 20cm wide though, so might be enough for 32-40 cells.

[@updownchoice3715]

I've heard you say leaving the balancer on all the time hurts the battery. Is there a way to quantify this? Why is the damage caused by top balancing ok but constant balancing not ok? If you look how those balancers work they constantly push-pull from the batteries at a regular frequency. I know its for a short time though. Just wondering if there are any tests you can do to quantify balancer battery damage. Maybe another myth-buster test you can do?

[@michaeldudley7840]

Andy has covered that many times in his previous videos.

[@xeroxcolortonersamizreik7999]

hi, have a nice day. we have solar system 48v / 10kw lithium battery (facility type) i need your help, did you have the formula which enables us to know ! (if have load AC voltage /5 Amp at home consumption in this case how much is the consumption DC/ampere of the battery) thanks

[@jean-pierrekrickx6517]

Hello Andy, isn't it harmful to the battery to only charge it to 80%? How can I send you an email to send some pictures of my installation? Many thanks for these informative videos. regards Jean Pierre

[@andreaszentner5868]

Danke!

[@OffGridGarageAustralia]

Vielen Dank von einem Andreas zum anderen Andreas!

[@davidkettell6236]

Thanks for putting in simple terms what should be obvious Andy . Unfortunatly the internet has more self appointed genii than the U.S. democrat party ,if thatwere even possible. Math is math and it will not change for anyone.

[@OffGridGarageAustralia]

Sometimes you have to step back a bit to see the full picture. It's pretty obvious for most of us but if you're new to all this, information are everywhere and you just don't know how to deal with it. The battery works fine like any other one, I have ever build...

[@HenkWagenaars]

Hi Andy, my lifepo4 already has 6541 cycles within 1/2 year how is this possible? I think because my total cycle capacity in the JBD bms was zero and should be 80% of 280Ah so 224Ah can this be reset Kind regards from the Netherlans in Europe Henk Wagenaars

[@Oli83two]

But I wonder about, that I have every day at 99,5% a deviation of 0.070v!?🧐 every time the same tree cells are increasing for a very short time, perhaps 15 minutes or so, than the neeeey balanced this out under 10mV. I charge to 55,5v, should I set down the voltage to 55,2v?

[@OffGridGarageAustralia]

There should be not much difference between 55.5V and 55.2V. If the same cells are peaking all the time, measure the voltage drop across the cells and terminals when charging/discharging with a constant current.

[@markbrettnell3503]

Yes 100 mV deviation isn't ideal at all, BUT! That's no worse then I've seen battery 2.0 running at times. So that's still really good considering it is FRANKENSTEIN!!!! 😋

[@OffGridGarageAustralia]

I think so too and with the NEEY turned on, it balanced nicely to 40mV with a second recharge.

[@markwright196]

weird how you assume 280 in each as the 304 will be at a lower voltage especially in that last 10%? And wouldn't the active balancer would be heavily balancing the 304 cell?

[@OffGridGarageAustralia]

You only balance when the battery is full (we don't bottom balance any more). It turns on at 3.4V, never below that with LiFePO4 batteries. I have made many videos about that here on the channel...

[@MrGunningpeter]

Hi, I have two 55ah batteries and two 52ah batteries (lifepo4 cells) can I run them in series if I dont fully charge them or discharge them ? I know its technically wrong but lack of funds are an issue and It would be great if I could use them.

[@OffGridGarageAustralia]

If they are all the same chemistry, yes, no problem. You can just fully charge them in parallel to top balance them and then put them in series for a 12V battery with 52Ah capacity. Like with any battery, the cell with the lowest capacity determines the overall battery capacity.

[@Bob.W.]

Thx.

[@PlexMulti]

We are waiting the new video andy!

[@tomassliauteris884]

Super!!! Keep doing!

[@opless]

Almost missed this! 😲

[@opless]

(that's what she said!)

[@OffGridGarageAustralia]

She said 'It looks like a solar farm' 😁

[@opless]

@@OffGridGarageAustralia looking forward to the next installment!

[@ericanderson9004]

Current is the same but voltage of cells are different. P=V*I You need to integrate over time and see what you out of each cell.

[@johncampbell2311]

Well I just ordered 8 batteries. Ishann Lifepo4 battery Store Estimated delivery date: Aug 8, 2023 Grade A 3.2V Lifepo4 280Ah Battery 4/16/32PCS High Capacity Rechargeable Batteri Vans RV EV😢 Solar Storage Electric Car Cell Pack 4PCS, CN US $580.16x2. I hope this is how my good seller?

[@ModernSurvivalSense]

The amount discharge per cell doesn't make sense. The higher capacity cell will have a different internal resistance from the rest based on state of charge... In theory, energy would flow from the larger capacity battery cell easier than the lower capacity cell.

[@OffGridGarageAustralia]

That's not the case though. The internal resistance does not change much as we have tested in one of the last videos.

[@mrgruisinge]

Understand the charge/discharge cycle. You are however not using the 304 AH batteries as 304 but as 280AH battery cells. So the full battery will be no more than the capacity of the weakest cell.

[@OffGridGarageAustralia]

This is always the case. Every battery has one weak battery which will determine the overall capacity.

[@PlexMulti]

Ευχαριστούμε!

[@OffGridGarageAustralia]

Thank you very much for your support🍺

[@cyberplebs6577]

🐸🐸🐸

[@BatteryBall]

👍👍👍👍

[@mflo1970]

Ohh quiero ver el matrimonio feliz victron fronius para una mejor aprovechamiento del sistema un saludo 👋

[@aaabbb1579]

Not right, you discharge the same Ampere, but not the same energy, because you have different inner resistance, hence different voltage., low resistance cells will have less voltage drop and less energy W= V*A same for charging. The resistance is not constant at different SOC either. That's the reason btw. why cells drift over time.

[@OffGridGarageAustralia]

Yes correct! I had the Ri component in there and some calculations but decided not to show it. Most people would be confused. Ah are easier to understand.

[@cskeise]

💙👊😎

[@paulcurtis5496]

Woot, like#1

[@OffGridGarageAustralia]

🥉

[@paulcurtis5496]

@@OffGridGarageAustralia hahahaha I medaled! 🥇

[@PlexMulti]

Hi 🎉

[@OffGridGarageAustralia]

🥇

[@4GoChris]

1st🎉😊

[@OffGridGarageAustralia]

🥈

[@charlieodom9107]

I have to disagree with you on your assessment of a fully charged cell. You state that they are not holding charge voltage after the charger is shut off, but they aren't supposed to hold that voltage. A fully charged lifepo4 cell is 3.35-3.4V, not 3.6-3.65 as you suggest here. I believe you are severely overcharging the cells if you are trying to keep them holding anything higher than 3.4v while resting.

[@OffGridGarageAustralia]

I agree with you but this is not what I meant. The voltage will go down after a while (quite a while) to 3.35-3.4V as you said, correct. There is a difference between Voc and charge voltage. Many think charging to 3.4V is fully charging the battery. If you turn off the charger at this stage, the voltage will not 'stick or hold'. While it will stick at this voltage, and even at a higher voltage, if the cells are absorbed. The voltage will stay even at 3.5V without charger for 15min or so. That indicates, the cells are fully charged and absorbed. No one should keep the cells at 3.4V or above all the time. that would overcharge them as you correctly stated.

[@charlieodom9107]

@@OffGridGarageAustralia After watching several of your videos, I notice you topping up the cells at very low currents as well. A 280ah cell should stop charging at 14a tail current, or 0.05C, which is when they are fully charged, according to the manufacturer. Forcing them to continue charging at less than 0.05C is overcharging, which is why you can get them to maintain a higher than 3.35V after charging. Anyway, I really enjoy your videos. Thank you for all your hard work and dedication to the off grid community.

[@BatteryBall]

👍👍