newbie q: 48V Lifepo charging upper limit?

Hi everyone, I have sort of a newbie question but I cant quite figure out what to google to have my question answered.

I have a SPF 5000es hooked up to a battery bank of 5kwh of lifepo4 batteries. I also have 10x250 watt panels in series.

When I am charging the batteries from empty up to full, it seems to max out at 1200 watts, even though the batteries all have a 100A BMS.

However, when im drawing a load, such as my air conditioner which is 2200 watts, my PV provides 1600 watts, and draws the other 600 watts from the battery.

My question is : where did the "other" 400 watts go? why cant my battery bank charge at 1600 watts? my PV can provide 1600 when my AC is on!

is it because I set the wrong floating charge or charging voltage? I understand the batteries limit the amount of current it can accept when its nearly full, but I see the same thing when it starts from nearly empty. and if I never draw a load, its a flat line at 1200 watts the whole time. what exactly is creating this upper limit? is it because my batteries are not balanced? ( I top balanced them many times ). or is this normal? that I get more total power when im drawing a load? I thought having a 100A BMS means I can charge the batteries at maximum 100A, which means I should be able to charge up to 4.8kw right? this has been bugging me!!!

100A BMS means 100A discharge and maybe a 100A charge. Sometimes, they're 50A.

Is your BMS communicating with your inverter?

EDIT: What that looks like to me is the PV maintaining an absorption voltage level where the battery can't accept more than it needs to maintain that voltage.

Do you know the state of charge on your batteries? How many 5kWh modules? What are the settings on your solar charge controller?

sunshine_eggo said:

100A BMS means 100A discharge and maybe a 100A charge. Sometimes, they're 50A.

Is your BMS communicating with your inverter?

EDIT: What that looks like to me is the PV maintaining an absorption voltage level where the battery can't accept more than it needs to maintain that voltage.

Click to expand...

no, I dont have BMS communication unfortunately - I have 2x 24V 100ah batteries in series, they each have a 100A BMS supposedly. I'll check to see if the discharge and charge are not 100A. they are "Power Queen 25.6V 100Ah 2.56kWh Deep Cycle LiFePO4 Battery with Longer Runtime, Built-in 100A BMS" on amazon.

I wonder if this is it? the batteries max out at around 600 watts charge?

Shimmy said:

Do you know the state of charge on your batteries? How many 5kWh modules? What are the settings on your solar charge controller?

Click to expand...

I have an external battery monitor "AiLi Battery Monitor" on amazon it measures current in and out and gives me an approximate percentage based on its measurement over time.

I know that even at 20% charge, it can charges at the same rate until it reaches 100% and the high voltage cut off. it basically charges at a flat rate no matter what the state of charge as as far as i can tell.

my inverter settings is set at 56.8V for the charging voltage and the floating voltage, 42V for the low voltage cut off.

but now you got me thinking maybe theres an inverter setting i missed...

What is setting 02?

sunshine_eggo said:

What is setting 02?

Click to expand...

it was set to 20A.

thank you so much you sir are a genius. This was 100% the problem. I bought a open box used inverter and 02 was set to 20A. the default is 60A so i think the previous owner set it to 20A.

wow i spent 2 weeks trying to figure this out. im glad theres a newbie section on this forum

thanks.