Help troubleshoot charging

[Aloyicious]

F9F65EA5-FDEF-4318-B4D6-E017000F2CB4.jpeg Please weigh in with your opinion.
I did a lot of research and ended up designing a system to power a small freezer in an outbuilding in New England.
I am set up as follows:
2 100w panels (22v 5.7amps) in series
2 more 100w panels (22v 5.7amps) in series
2 200w panels 24v 11amps in series.
then all these are wired in parallel and just one positive
and negative coming off the roof inside. I have two lithium Weize 100ah 12v each in parallel. Using an Epever 4215bn scc. And a no name pure sine 2000w inverter. My freezer takes 100watts to start and 65w to run.

I see 43(+-) volts on the scc monitor but the batteries only at 12.7v. Occasionally, without anything changing or the freezer even cycling on or off, the system will seemingly charge to 14.6v. I hardly ever seen amperage coming in on the monitor, just volts and the battery icon might read 14.6 but it is not full as it should be.

[Bala]

It may be an issue with the Battery bms and your setup. Also not all lithium drop ins are designed to parallel so I assume these are?


I would take the lithiums out and put a lead acid in to test. Any car battery would do, you wouldn't need to connect the inverter.

[checkthisout]

F9F65EA5-FDEF-4318-B4D6-E017000F2CB4.jpeg Please weigh in with your opinion.
I did a lot of research and ended up designing a system to power a small freezer in an outbuilding in New England.
I am set up as follows:
2 100w panels (22v 5.7amps) in series
2 more 100w panels (22v 5.7amps) in series
2 200w panels 24v 11amps in series.
then all these are wired in parallel and just one positive
and negative coming off the roof inside. I have two lithium Weize 100ah 12v each in parallel. Using an Epever 4215bn scc. And a no name pure sine 2000w inverter. My freezer takes 100watts to start and 65w to run.

I see 43(+-) volts on the scc monitor but the batteries only at 12.7v. Occasionally, without anything changing or the freezer even cycling on or off, the system will seemingly charge to 14.6v. I hardly ever seen amperage coming in on the monitor, just volts and the battery icon might read 14.6 but it is not full as it should be.

Are you running out of battery?

If not, the batteries are just fully charged.

[venquessa]

When you say 22v panels I assume you mean the open circuit voltage.

~44V array voltage suggest it is in current limiting phase. Such it believes the batteries only want 0.3A. There are several reasons to get to this state.

It would be perfectly normal if the panel had recent just finisihed its boost charge phase and completely charged the battery. It will drop back to float and occasionally "recon" lower voltages to see if the battery needs charged again.

What does the battery voltage say if you switch off the panels and start up the fridge? If it stays over 12.6V the battery is full charged (LA), (~13.4V LFP). If instead if sags down to, or below 12V something is possibly incorrect.

How old is the battery? Is it lead acid? Deep cycle?

Tired lead acids have a tendency to develop a surface memory charge when used for light cyclic duties. So they never seem to have any capacity and always appear fully charged until you put them under load. There are some things you can do to get a bit more out of them, but usually ordering new ones is the best answer, or go lithium.

[wine_guyu_3]

I have a similar problem, so forgive me for piggybacking on your thread.

I believe that I am having issues with the Charge Controller
Model OUTBACK POWER 80AH MPPT Controller.
Purchased 3/29 2021

This unit is in a remote cabin.
Power is not on when I am not there. The unit is keeping the batteries charged.

System
6 100 Watt solar panels, 3 in series, 2 sets in parallel.
8 875 MCA lead acid batteries in an insulated battery box. 2 sets of 4 in parallel. 12 volt system
2500/3500 watt inverter. Off when I'm not there.

I was up there around Dec 29 and had almost no power. Batteries went down to 10.8 volts overnight. The inverter shut off for low volts. I only run a refrigerator and some LED lights when I am there. Once again this is a bank of 8 batteries.

Is it not a good idea to just have the batteries charging without any load for a month or two?

Side issue; Do I need to ever clean the MC solar connectors? Charge controller shows up to 87 volts, but no current???

Any inputs would be helpful.

[chrisski]

I think you have an FM80 charge controller. You’ll get better help at the Outback forum.

i would not clean the MC4 connectors. Especially for a roof installation. I would look at them as part of the troubleshooting. This would be towards the end of my list.

Recommend check your batteries and store in DOD as per the spec sheet. When I had lead acid, I’d fully charge, disconnect from everything and come back two months later and hook back up.

can you do a specific gravity test or charge the batteries with a generator?

can you verify the CC voltage with a multimeter? 87 volts is a safe voltage for the charge controller.

I use FM100 charge controller and those have reset the settings. Recommend you check your settings.

A couple things can cause the FM80 not to charge like a wake up current.

iIs there a spare controller you can hook up?

May need to reset the charge controller by removing all the power by flipping the breakers for DC in and DC out.

[littleharbor2]

8, 12 Volt batteries in parallel is a very difficult thing to keep balanced charging and load paths on. The voltage dropping the way it does when you put a load on it tells me your batteries are most likely shot. Although you could have some connection issues with all those connections, you're much better off with 6 Volt golf cart batteries and at least you would have half the connections with the same amount of power. Better still, add bus bars to your system, simplifying wiring

[wine_guyu_3]

I tried disconnecting and reconnecting the controller. Does not seem to do a lot. No real current.
Connections between batteries are 1 foot long welding cables.... 1/0 I believe.
Two of the batteries were a little low on water, so I topped them off.
One connection was a little loose, so I tightened it.

I disconnected the two battery strings. One I left on the controller. The other I charged for a few hours with the generator.
I will check again the next time I go up.

I verified the input voltage and battery voltage.
I think I have 8 junk batteries.... 2 years old.

Why did this happen? I'm not sure if I ever went past 20% discharge.
Is it a bad thing to leave the charge controller on while I'm not there?
The controller "should" put a float charge on, and then "maintain" them?

I was going to add a bus bar, but I wanted to be able to check water level easier.
It was easier with short cables. 4 batteries on top shelf, 4 on the bottom shelf, tied together at the junction box on the side.

[chrisski]

Since these are FLA, there is a chance of recovery through equalization.

for this and other questions, if your battery does not have a spec sheet, look here:

https://www.trojanbattery.com/resources/guides-manuals-and-warranties

and look at the battery guide and maintenance guide.