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.