Can you run multiple charge controllers from the same solar panel to separate battery banks?

Can you run multiple charge controllers from the same solar panel to separate battery banks which have different battery composition.
I test with two cheapo ebay controllers and a mismatched battery setup to see if it ends in a nice twin-bank solar setup or fiery death.
Forum link referenced in the video:
electronics.stackexchange.com...
Ebay link for the charge controllers I'm using:
www.ebay.co.uk/itm/373950592210
----------------------------------------
Background:
So this is a bit different from my usual content but I bought a little transit connect so I can take the bikes to places and go riding. That van has a small solar install and I have two pairs of batteries in the rear footwells.
The first set is a pair of car batteries giving approx 135ah and the other set is a new pair of deep cycle lead calcium "maintenance free" batteries claiming 150ah.
They have slightly different usage cycles so i can't really connect them directly in parallel but I want to use one bank to run my fridge and one bank for lighting, cooking, usbs, laptop & tools etc.
That way i can let the fridge run and if it runs out of battery while I'm out riding I'm not without power for everything else. A separate charge controller also means I can use the "dawn to dusk" or other timer features which that controller has, without affecting stuff like my lighting and ability to communicate.
So if i split the cable from the panel across two or more charge controllers, is there ever a situation in which the two battery banks are directly connected to each other?
So if my fridge battery was flat but my main one was ok, and the sun comes out and switches on charging for both controllers, is there a chance of a "backwash" of current as they try and equalise? (which seems like it could be bad) or can they exist independently and at different levels of charge, but still charge together opportunistically off the same panel?
LETS FIND OUT!
My links:=============================== For YZF-R125 owners looking for help go to www.r125forum.com/ Twitter (realtime updates): / northcustmy website (build projects, blog, discord):northcust.co.uk/category/yama... (support the channel!): / northcust

[@AATechvideos]

this video look like a horror movie going no where

[@alibear57]

There's ALWAYS somebody like you who tries to belittle folk who are experimenting and helping the rest of us! Go get a life.

[@jimtmurphy]

Love the fire extinguisher nearby in the video, LOL! very helpful, thanks!

[@NorthCust]

Safety second! xD

[@alfonico6898]

Many thanks. Very clear.

[@ronellegaspi6747]

Me also thinking of this.. Just now, so ive search here on youtube... I found you doing man tnx anyway... And i like your background sound.... Cheers man maybe try it for. myself too when i have the other controller.. Tnx Godbless!

[@NorthCust]

thanks very much! normally people complain about "the awful music" so this makes a nice change ;) lol

[@BOREDANDWELLBORED]

So it's been a year, do you still do this set up? What's the side effects? ​@NorthCust

[@ellenrobieruiztoledo8146]

I been looking for something like this due my other 1 panel has been cancelled by the courrier for no reason, and i ended up having 2 controllers and 2 different kinds of batteries. A LEAD acid and a Lithium. So i must gonna try this instead. THANK YOU FOR TRYING THIS FOR US.

[@itsmisterchris]

Love the intro 😂😂😂 just missing a machine gun shots

[@NorthCust]

UPDATE: I've actually done this setup in my van now and whilst it seemed to work ok without the diodes, out of curiosity I ended up testing it with a couple of 10amp schottky diodes (biggest i could find) inline on the positive just before each controller and whilst I can't quite pinpoint why i feel better about it, i do. Maybe I just don't trust the controller manufacturers , maybe it's just OCD. With the diodes there is a tiny voltage drop of about 0.1-0.2v (a ssuspected) which i don't like but maybe that's the price of peace of mind. Even though the diodes were rated as 10 amp a piece I found they'd get quite warm even just with the 6 amps max from my panel, so found doubling up (2 diodes in parallel per charge controller) seemed to spread the load better. That is however with one of the controllers (in the van) being a different one so they're not an identical pair like in this video (one is the eco-worthy controller which came with my panel, which I like a lot). Having identical controllers may have been one of the reasons why things seemed to work ok in this video.

[@rsmith16384]

I thought I could parallel diodes also, but found that one will still get super hot. ???? Quantum physics

[@jasoncampbell2808]

I just installed a panel, charge controller, and battery in my storage building today. The plan is to hook up some LED light strips in it. Behind our storage building is a chicken coop where we have 2 Blink outdoor cameras. These run off of AA lithium batteries which die pretty quick because of all the movement, and they are expensive. I was thinking of adding a charge controller and small battery at the coop just to use the 2 USB ports on the controller as power for our 2 cameras. Since I have a solar panel at our storage building I am wondering if I can use a splitter on the panel to run underneath our building to the chicken coop and the other charge controller and battery. This video is as close as I've found. It is essentially the same as my idea, only I plan to use MC4 splitters at the panel.

[@NorthCust]

I suspect you might be better off taking power from controller or the batteries, surely that's gotta be neater, involves less controllers and also don't underestimate how much power you lose due to attentuation. 2x solar cables means 2x attenuation. 2 controllers worked but it was a bit confusing and i don't feel like it was really ideal. Instead how about you just run the solar to the storage building as you have and then run a 12v line from there to the coop and install a pair of 12v usb sockets like these (or similar) : www.ebay.co.uk/itm/304118526870 I suggest these because I found that even in my small van I was getting quite noticable attenuation (voltage/power drop due to long wires). I knew that it was worse at low voltages but wasn't aware just HOW extreme it is. To that end, using the 12v usb sockets has a secondary benefit - namely that the sockets will accept a range onf input voltages so if you get some attenuation on the lead from the controller/batteries to the usb sockets, it doesn't matter bc the sockets steps 12-24v down to 5v anyway so the effect of attenuation ought to be effectively eliminated in the stepdown process. Hope that helps :)

[@Greviouss]

how does this effect the amp generation / draw at the controller, is it halved or do both controllers get the full amperage or do they fight for it based on the battery level / max? Would love to see this with a better controller that can provide that data ... P.S. im gonna be doing this myself soon in my house ill let u know if you dont tell me first :D

[@NorthCust]

so tbh this has been quite interesting as after doing this experiment I replicated the same setup in my van and ended up asking myself the same question. The controllers I used in this video didn't show the input current, only "charging" or not (they're quite old) but the ones in the van DO show the input current (they're the eco-worthy ones which are much nicer) and gave much better info. What I found is that both controllers seem to have a "full charging", "not charging" and "trickle charging" state, presumably depending on the voltage of the battery bank they're attached to. So if bank 1 is full but bank 2 is low then controller 1 will be in "not charging" state (0a) or "trickle charging" (2a). Same goes if the other way around. However if both banks are low then both controllers seem to be in "full charging" state and it does actually split the power between them, though not always evenly. I still don't fully understand why the uneven split, but I guess it's to do with how much power each bank seems to need. It's actually been quite rare that I've had both banks low but I have seen it where they were then gettign pretty much an even split, but most of the time one or the other is getting the majority. Either way *somehow* they seem to figure it out magically by themselves and it's been running like that for a few months now with no problems :) Maybe I need to make a follow up on this video and dig into this a bit more since the van setup gives a bit more info. Hopefully that helps :)

[@panospapadimitriou3498]

so if the pv array not exceed the amps and volts of any of 2 mppts its ok!! only its unexpected the way it equalize the charging between them that depends of the battery internal resistance if nothing else change any parameter ...right ? ? ? ? ??

[@NorthCust]

hi :-) 1) neither of those charge controllers are MPPTs, 2) I think bear in mind that both chargers may not always be in "charge" mode, s o the PV array shouldn't exceed the amps and volts of *1* charge controller (not both) since most of the time it's only one controller active. 3) I have no idea what you mean re internal resistance, sorry. NC

[@dalidalii9871]

Instead of buying second charger just buy ups and inverter 1st battery set connect to inverter connected to solar charger then connect inverter to ups then your loads must be connected to ups make sure both ups and inverter can handle your load also make sure your ups charger Amp is little bit high it Will charge your batteries with electricity from inverter when inverter shut down your ups will take over my solar system is nonstop

[@yusifsuleiman5502]

Good to hear that, love your idea, Man. Please, share your diagram that of with the diode. I really want to do similar project. Greetings from Nigeria

[@NorthCust]

Hello! The circuit diagram i based it on is here (there was a link in the description): electronics.stackexchange.com/questions/182043/multiple-charge-controllers-on-the-same-solar-panel Basically the diode/s need to go between the end of the positive cable (from the panel) and where you would normally plug the positive lead into the controller, so in my case that looked like this: northcust.co.uk/wp-content/uploads/2022/08/IMG_20220810_173709667_dual_solar_controller_with_diodes-768x1024.jpg So the one red cable which comes through the wall is the positive from the solar panel, you can see the two diodes in parallel going from the cable connector to the top charge controller. Then the red cable goes back into the wall and down to the other controller, again with diodes just before. The line/ring on the diode should point into the controller or you won't get any charge. I ended up using 2 diodes in parallel since whilst they were rated 10 amps (which should be plenty) they were getting warmer than I was happy with. Doubling up the diodes effectively splits the current load across them and now they barely get warm. I did notice a slight voltage drop with the diodes and that's probably 2x with 2 diodes in parallel but haven't found that to be a problem in practice, and the setup just seems to work better with the diodes in place so that's what I've stuck with. Having the diodes etc visible/exposed like that isn't ideal but this is still very much a work in progress. I used small sections of heatshrink tubing over the legs of the diodes to avoid having exposed connections. Each controller feeds a separate battery bank - a main 150ah pair of deep cycle lead calcium batteries for lighting, usb sockets, and also runs the small inverter for cooking, charging laptop etc, and there's a second bank with two car batteries (75ah + 60ah), which run the fridge only. The fridge uses a peltier cooler and is not super efficient, so uses quite a lot of power which basically used all the available watt-hours from that bank, so as a sort of workaround I found a timer circuit ( www.ebay.co.uk/itm/354108405211 ) which runs the fridge 30 mins on, 30 mins off in an endless cycle and used only 50% as many watt-hours/electricity. As long as I have a bottle of ice in the fridge to help it seems to stay plenty cool like that. When the fridge is running there isn't really much solar left to charge the batteries, and particularly the first bank doesn't really get to charge much, so the 30mins cycle actually ended up playing an important role in allowing both banks to charge at full speed (which was not a problem i had considered beforehand). Currently (summer) this setup works very well but I've seen on some more cloudy days that there's not really enough juice from the one 120w panel, so am hoping to add a second one before the winter and maybe a compressor fridge which is hopefully more efficient. Then I think we should be good :)

[@yusifsuleiman5502]

@@NorthCust Thank you, Sir. I made the connection as described, only that the charging is not with full capacity and the diodes temperature going high. What should I do to reduce the heat from the diodes, and how can I increase the power of charging. Appreciate

[@stirbueduard7351]

Why would there be any Equalisation going on since there’s 2 batteries Involved?

[@rsmith16384]

Thank you for testing this. I have a small offgrid setup, its producing alot more than I am using, so im looking at one of those plug in grid tie inverters to put some into my house, and this is how im gonna do it. Only concern now is competing mppt algorithms, one might hog it, or they could keep fighting endlessly

[@svenshanah]

I don't think you'll have that issue. If I'm understanding u correctly..Will Prowse did a video on just that some years ago, proving that the controllers won't fight each other. Might be worth a peek.

[@NorthCust]

hi, thanks! Hopefully it was useful. I actually just recently happened to get to test using two MPPT controllers on the same array to feed two separate banks and that did NOT work as anticipated. With my 4 panels in series I'd usually make ~85v on each mppt individually but when connected together the input voltage reading for both controllers dropped to 17v, and also only showed the current input I'd expect on one panel (~7a), not (e.g. 4 in parallel - ~28a). I didn't test it for very long beyond that but that was with two almost identical controllers (Renogy Rover 20 and rover 30). I can't say conclusively there's not a way of making it work but in my brief test, with my setup, it did not seem to work. Sadly I don't really understand enough about electronics to really speculate what might be happening.

[@AngeloXification]

There shouldn't be an issue, just the amperage would drop between the controller dependent on the battery internal resistance (charge state) which would mean each battery charges a bit slower I think

[@NorthCust]

right, so basically they *ought* to figure it out amongst themselves. And havign run a very similar setup in the van for a few months now it does seem to work. HOWEVER, I recently replaced the batteries in my second bank (from a mismatched pair of car/starting batteries) to the same ones as my main bank (deep cycle lead acid/calcium) and as an experiment i connected them all up as one bank (4x12v in staggered parallel) and they seem to charge "better" somehow. With 2 banks of 2 batteries each I would hardly ever see voltages above 12.7, but as a single bank (even though the same crappy weather, which is even gettign worse) I'm seeing 14v+ occaasionally. Go figure.. I'm still not exactly clear on why this is but I suspect multiple devices (esp with diodes whcih drop a little voltage) means multiple inefficiencies, and also perhaps neither bank ever fully reaches the final charge state (sorry i forget the name of it but where the resistance gets higher and it needs a higher voltage). So it seems like the combo of crappy weather and multiple banks means none of them ever really get the love they need to hit optimal charge. A recent very wet/cold night in the van in uk winter seemed to highlight this and got me delving deeper down the rabbithole of better efficiency which led me to MPPT charge controllers. I now have a shiny new renogy 30 amp MPPT controller waiting to go in and I'm planning to switch to having the panels in series to give a higher charging voltage which is regulated down to optimum for whatever the current charge state is by the MPPT controller. More on this to follow I'm sure!

[@AngeloXification]

@@NorthCust Thanks for the update haha, I literally got a new inverter with inbuilt MPPT charging. I've been getting about 30% more power per day.

[@NorthCust]

@@AngeloXification oh cool! thanks for letting me know :) that seems to be about in line with what they claim for MPPT controllers which is very reassuring to hear. It also seems like not everything that says "MPPT" on it actually is, esp if it's cheap off ebay, which is why I ended up overspending a bit on the renogy, but having received it, it's such a beautifullly engineered bit of kit and the support is excellent. Any spare time I've had these last few weeks (which has been very limited indeed) has been spent trying to insulate the ply walls and bare metal ceiling but now that's more or less done, next up is to see where to fit this renogy device, which is quite a bit chunkier than the dinky eco-worthy pwm controllers.

[@AngeloXification]

@@NorthCust haha when its chunky it feels like quality. Pretty much my same experience. More power to ya ;)

[@svenshanah]

@@NorthCust Sounds like Renogy turn it around? Three years ago or so, thinking their stuff looked elegantly professional, I got some of their components.. then had problems, and couldn't get proper customer service to save a life. Buddy had the same issue, just flat blew him off.. until he made a Renogy Rant video. THEN they finally replied. I had already wrote them off for good, but to their credit, they told him basically in so many words, that they knew they sucked, and that people were furious, but said big changes were being made behind the scenes and things were going to change in all depts in the future. Sounds like maybe that happened a while back.👍

[@alibear57]

Thank you for this experimental / instructional video. I'm also wondering if you've had any longtime success with this? I have just bought a Lifepo4 battery, for my camper-van, but the existing setup, is fully designed for Lead Acid (including charging from Solar Panel & Van Alternator). This has caused a dilemma for me, because I want to keep both systems (but the LifePo wouldn't be able to get the charge from the alternator, and the solar controller is only able to pick one battery type at a time, so can't just ADD it in). I decided to try a splitter cable, from Amazon, and a second controller (like your ones). When I connected it all up, I got excited, because both controllers were showing them as charging each individual set of batteries. But, after about 10 mins, the controller to the LifePo showed no charging from the solar panel. I'm puzzled as to the reason, so I'm thinking that your diode idea might be my solution. Unfortunately, I am a complete novice with that kind of electronics. I'll keep studying your plans and hopefully get my system to work. Cheers

[@NorthCust]

I ran two controllers for quite a while in the van in the end becaus eI too had mistmatched banks - my main bank was 2x75ah deep cycle lead acid and the other bank was 1 60ah and one 75ah car starter battery. It did seem a bit weird at times re how it decided who got the power but it did actually seem to work. It seemed to work ok without the diodes but I also kinda didn't really trust it without so ended up leaving them on. With a lead acid and lifepo setup like yours I would have thought this sort of arrangement but with diodes on the solar input of each controller ought to work just fine. Good luck! :)

[@phils6009]

Alibear , ive got the same situation , how did you get on as im going to try the same thing soon .

[@furysolar]

Nice, did you try using Two MPPTs connected parallelly to single Solar Array, and charging Single or Multiple Battery banks?

[@NorthCust]

please see above..

[@glennalvarez0223]

is your set up still working? im looking for this video and i want to know of it realky works and going well... i just bought another similar charge controller and plan to use for my 2 ups 12 v 7ah battery, my old one was 70ah sealed gel battery, can i do this trick in my set up??? please help me bro. good day

[@NorthCust]

hi.. I ran basically that setup in my van for about 3-4 months and it worked pretty well (different charge controllers [the eco-worthy ones] but still pretty cheapo ones switching ones, not mppt, 2 pairs of batteries, one pair 75ah lead-acid-calcium totalling 150ah, and two mismatched car batteries totalling 135ah) I had two 120w panels feeding it and whilst it was a bit confusing what it was doing at times it did actually seem to work pretty well. I had one bank to run the fridge and one for everything else and i had 0 problems with it. Eventually I got a second matching pair of 75ah lead-acid-calcium and now have all 4 wired up into one bank and switched to a single controller, with a view to fitting the new renogy MPPT controller I have sitting here for better efficiency and better charging. As far as I understand it...as long as you have each controller set to the correct battery type for what's attached to it I don't think there should be a problem. Also apparently you can mismatch parallel wired batteries (NOT SERIES)... so if you have a 70ah sealed/agm and a pair of 7ah sealed agms then you can parallel them on the same bank np. Apparently it's something to do with the internal resistance of the batteries whcih just figures it out, tho personally I'd prefer "slightly mistmatched" like my 70 ah and 65ah rather than 7ah and 70ah. Also with parallel afaik wire in "staggered parallel" to maximise battery life. I hope that helps, good luck :)

[@glennalvarez0223]

@@NorthCust thank you so much for a very clear info... good luck bri.

[@XRinger]

6 Amps x 0.2V = 1.2 watts. If it's a small body diode, and can't dissipate the heat, it's going to get warm. Thanks for posting this. I found your video, because I was wondering if a Back-up system, designed to provide short term 120V AC power during a grid failure, (for a freezer and WiFi etc) could 'Share' it's PV panel output during the day, when the back-up battery bank is already fully charged. Maybe Night-Time measuring for voltage on the charge controller's PV input, to see if any battery bank voltage is back-feeding out of the back-up system's charge controller, to the PV. If there was any leak-back voltage, it might try to run the add-on load/charge controller or add-on grid-tie inverter at night. Draining the battery bank. I have a spare Morningstar Tristar 45A that I could use on an old tired out LA 48v battery bank. Maybe I'll wire up an experiment and see if my 800 watt PV array can run both a Lipo & LA bank. Maybe dual charge controllers can charge up both banks simultaneously,? without too much infighting.

[@NorthCust]

the diodes I used ont he van were 10a a piece and even though I was never seeing more than 6a even at peak sunshine, they were getting warmer than I was comfortable with but doubling up (diodes in parallel) sorted it adn that's how they stayed till I (just recently) upgraded the batteries in the second bank to be the same as the first, and linked them into one big bank, which also means no more need for diodes. The night-time monitoring idea interesting, hadnt thought of that. I suppose that ought to do it, though from what I could tell these controllers act as switches and if true those switches would likely be "off" at night. My concern for "leak back" was more about ive say I've almost depleted bank1 and somewhat used bank 2 (so both need charge but are unevenly depleted), then when there's sun and both controllers are switched ON, is there *then* going to be any leakback, since if there was it could be sudden and dramatic and that's where problems might well arise. I'd like to think that the controllers would have a little silicon in there to prevent leakback that but did I trust el cheapo ebay controllers to do that? no. I could have emailed eco-worthy and see they know, they seemed pretty good overall, but my patience for support issues was also depleted, hence the inline diodes stayed just in case despite the observed everso slight (0.1v iirc) voltage drop.

[@juruelflorofuerte8904]

What is the value of diodes you used

[@NorthCust]

These were 10A schottky diodes from here: www.ebay.co.uk/itm/284710038307 which were the highest rated I could find at the time. Since then I've found some higher rated ones (up to 20A) here: www.ebay.co.uk/itm/283186713698 Even though my panel only makes

[@BOREDANDWELLBORED]

​@NorthCust can I do this set up without diodes? I don't want to add diodes

[@reamtm1]

Very bad video si confused