Batteries won't charge on small solar system

[daveoflave]

Hey all,
This is probably really a battery question (maybe not for this forum) but I'm asking here anyway because it's tangentially related and this community has been aweseom and helped me before.
Problem: 3 battery bank (parallel) won't charge from solar panels anymore.

What happened: It was all working great, until I just swapped out the 4awg cables from the solar charge controller to the bank. If I disconnect/reconnect everything, the controller shows it's pushing through up to about 17-18 amps for a minute or so, and slowly dies down to zero over 2-3 minutes.

My set up:
It's a small system built to power a full sized refrigerator indefinitely
-8 eco-worthy 200 watt 10.83 Amp panels
-2 groups of 4 panels connected to 4-branch Y-connectors, going to 8 awg pos/neg cables
-2 strings of those 8 awg cables going to the charge controller
-60 amp Renogy Rover charge controller
-4 awg pos/neg from charge controller to first battery in bank
-all cables in bank and to inverter are 2/0 awg
-2x 280amp 12v, and 1x 200amp 12v battery, all eco-worthy LiFePo4 (I know, different capacity batteries in same bank, but same type type/brand/voltage.)
-each battery has a Camway shunt from Amazon (configured them for max 200amps on the 280amp batteries)
-pos/neg 2/0 awg cables from neg contact of first battery and pos contact of last battery in bank over to the inverter
-200 amp fuse between the bank and the inverter on neg cable
-GearZarr 2000 watt inverter

So this has been powering my fridge for over 45 days (not sure exactly, but it's at least that long). It's a bit overkill, but it's dependable. I'm usually cranking about 59-60 amps through when it's sunny, after the fridge ran on battery all night. I wanted to test hooking the charge controller to the pos of one end of the bank and the neg of the other end of the bank (they were both going into the first battery in the bank, same end). As soon as I did that - nothing will really charge anymore. As mentioned above, if I disconnect everything and reconnect, the charge controller shows it's pumping in amps for a couple minutes, but then dies. The shunts each say that 2 of the batteries have zero amps, but 14.2 volts, and the middle battery still shows 136 amps, also 14.2 volts. I took a multimeter to the contacts for each battery, it reads 14.2 volts ok.

I then bought a charger to just try to trickle charge each battery. Tried hooking it up to one, and it gave all the indicators that it was charging (it has these 4 successive flashing lights until they're all solid). Waited until they were all solid for a few hours, hooked up the shunt again, and boom - 0 amps.

I also have a cheapy Renogy 20amp charge controller (not mppt, no digital reader or anything), and hooked it to the bank with a couple of the panels running into it - same deal, the shunt showed no charge, but the charge controller showed that it was receiving juice from the panels by its green indicator light.

To me, since I've tested multiple charge controllers and gotten the same result: it seems like the battery. But these things are crazy expensive, and I don't want to just give up on them without some expert advice. Can I troubleshoot or reset them in some way? I have to imagine that when I swapped my connection cables to the charge controller, something went wrong. But there were no flashes/explosions/any noticeable signs of issues when I did it...

Pardon the dusty look of my gear, it's spring in central Florida and that's the ridiculous amount of pollen that I just can't keep up with....

Any ideas? Are my batteries probably hosed?

 

[Mattb4]

A bit difficult to trace your wiring from the image. Since your batteries are different capacity but were working for you before you changed you wiring from the SCC. normally I would think you have a SCC issue, but you say you have tested others and are still having problems with charging. So at this point I would recommend disconnecting all parallel batteries and try to use one at a time and see if you can get it to charge properly.

Your shunt meters could be defective so I would do voltage testing as you troubleshoot further. A DC clampon ammeter would be handy if you have one.

 

[seneysolar]

Hey all,
This is probably really a battery question (maybe not for this forum) but I'm asking here anyway because it's tangentially related and this community has been aweseom and helped me before.
Problem: 3 battery bank (parallel) won't charge from solar panels anymore.

What happened: It was all working great, until I just swapped out the 4awg cables from the solar charge controller to the bank. If I disconnect/reconnect everything, the controller shows it's pushing through up to about 17-18 amps for a minute or so, and slowly dies down to zero over 2-3 minutes.

My set up:
It's a small system built to power a full sized refrigerator indefinitely
-8 eco-worthy 200 watt 10.83 Amp panels
-2 groups of 4 panels connected to 4-branch Y-connectors, going to 8 awg pos/neg cables
-2 strings of those 8 awg cables going to the charge controller
-60 amp Renogy Rover charge controller
-4 awg pos/neg from charge controller to first battery in bank
-all cables in bank and to inverter are 2/0 awg
-2x 280amp 12v, and 1x 200amp 12v battery, all eco-worthy LiFePo4 (I know, different capacity batteries in same bank, but same type type/brand/voltage.)
-each battery has a Camway shunt from Amazon (configured them for max 200amps on the 280amp batteries)
-pos/neg 2/0 awg cables from neg contact of first battery and pos contact of last battery in bank over to the inverter
-200 amp fuse between the bank and the inverter on neg cable
-GearZarr 2000 watt inverter

So this has been powering my fridge for over 45 days (not sure exactly, but it's at least that long). It's a bit overkill, but it's dependable. I'm usually cranking about 59-60 amps through when it's sunny, after the fridge ran on battery all night. I wanted to test hooking the charge controller to the pos of one end of the bank and the neg of the other end of the bank (they were both going into the first battery in the bank, same end). As soon as I did that - nothing will really charge anymore. As mentioned above, if I disconnect everything and reconnect, the charge controller shows it's pumping in amps for a couple minutes, but then dies. The shunts each say that 2 of the batteries have zero amps, but 14.2 volts, and the middle battery still shows 136 amps, also 14.2 volts. I took a multimeter to the contacts for each battery, it reads 14.2 volts ok.

I then bought a charger to just try to trickle charge each battery. Tried hooking it up to one, and it gave all the indicators that it was charging (it has these 4 successive flashing lights until they're all solid). Waited until they were all solid for a few hours, hooked up the shunt again, and boom - 0 amps.

I also have a cheapy Renogy 20amp charge controller (not mppt, no digital reader or anything), and hooked it to the bank with a couple of the panels running into it - same deal, the shunt showed no charge, but the charge controller showed that it was receiving juice from the panels by its green indicator light.

To me, since I've tested multiple charge controllers and gotten the same result: it seems like the battery. But these things are crazy expensive, and I don't want to just give up on them without some expert advice. Can I troubleshoot or reset them in some way? I have to imagine that when I swapped my connection cables to the charge controller, something went wrong. But there were no flashes/explosions/any noticeable signs of issues when I did it...

Pardon the dusty look of my gear, it's spring in central Florida and that's the ridiculous amount of pollen that I just can't keep up with....

Any ideas? Are my batteries probably hosed?

Are the batteries indeed drained? Sure they are not fully charged?
Load up the inverter and see if battery voltage drops/charge controller kicks in.

 

[seneysolar]

Its hard to read the screen but it looks like battery voltage is 14.4 correct?

 

[KnobCountry]

Took awhile to trace all those color changing wires but I think I got it and I believe it is correctly wired for parallel with the neg tapped to inverter on the leftmost battery and the positive tapped from the rightmost.

Try wiring it temporarily without the fuse connections or inverter just to see if it will charge without them.

Then add one component back at a time .

 

[finite]

Personally even with paralell circuits i dont terminate on 1 battery and prefer to have them terminate on each end cell, distance matters with DC since you are effectively doubling the length compared to an AC circuit

 

[daveoflave]

Took awhile to trace all those color changing wires but I think I got it and I believe it is correctly wired for parallel with the neg tapped to inverter on the leftmost battery and the positive tapped from the rightmost.

Try wiring it temporarily without the fuse connections or inverter just to see if it will charge without them.

Then add one component back at a time .

Oh, sorry I didn't mention that I had done that. Each time they still reflected the same "0 amp" reading on the shunts. But - seems it's been charging the whole time and the shunts are just bad (or suddenly somehow misconfigured; I'm not sure).

 

[daveoflave]

A bit difficult to trace your wiring from the image. Since your batteries are different capacity but were working for you before you changed you wiring from the SCC. normally I would think you have a SCC issue, but you say you have tested others and are still having problems with charging. So at this point I would recommend disconnecting all parallel batteries and try to use one at a time and see if you can get it to charge properly.

Your shunt meters could be defective so I would do voltage testing as you troubleshoot further. A DC clampon ammeter would be handy if you have one.

Yeah, took a multimeter to each, they're all reading 14.2 v, which was so confusing to me. I don't have an ammeter, but I should invest in one. Thank you @Mattb4 and @seneysolar - you both made me realize it likely is the shunts and nothing else. I hooked the load into it Sunday night, and the fridge has been powered by the bank for about 36 hours now. During the day, I see the previously "0 amp" readings on the shunts of the 2 "bad" batteries in the bank slowly climbing up, and I'm seeing spikes of amperage throughout the day of 55-57 on the charge controller. So it really must have just been the shunts reading improperly... I mean actually, they likely still are. If everything is charged and 2 of the batteries are still reading around 10-20 amps after 36 hours of this... wondering if maybe I should just replace them. I'd be really happy to think only the shunts need replacing rather than these insanely expensive batteries!

 

[daveoflave]

Personally even with paralell circuits i dont terminate on 1 battery and prefer to have them terminate on each end cell, distance matters with DC since you are effectively doubling the length compared to an AC circuit

Thanks for confirming that's the best way - that is precisely what I wanted to try when this all went down hill. In my post, I mentioned I "swapped out the 4awg calbes" but failed to mention *why* I swapped them out - it was for longer cables so one of them could reach the other end of the bank! Sorry. I must have done something to make the shunts misbehave during that process somehow though. But I re-arranged the cables to be back on the first cell's contacts when I took that photo for this thread, because at that time I thought maybe it was just the cables themselves. Based on the whole conversation above though (now that I think the batteries are fine and the shunts are the problem), I'm glad to know I can/should switch the contacts back to opposite ends of the bank.

 

[AmpD]

Soc memory issue? Could the shunts somehow be remembering values from before and now need recalibration for new soc values?