Charging Batteries

[threepets]

I use the MPP LV6548 6500w off grid Solar inverter (CSA) 48v 110vac / (2 units for 220vac )DUAL MPPT solar charger 120A. With 8 - 465w Panels and 4 - Lifep04 51.2v Batteries. I am not Grid connected , but the LV6548 is AC connected to the grid for times when there is no solar and batteries are depleted . I have set up a solar powered Breaker box for my home and power 6 circuits throughout the house. The MPP Lv6548 now runs 24-7, nearly a year with 4 batteries and no issues. I just let the inverter run the show. On a couple of occasions(just recently) the batteries have run done and no sun to bring them back so the charger (MPP LV6548)kicked in and charged the batteries back to 100% off the grid by having the LV6548 plugged in to the grid.(old picture of Inverter and battery, now using added Battery Box and batteries ) The other night we ran out of Battery again ,the inverter started charging and when I checked the batteries (in the middle of the night) 2 batteries were depleted to 0% SOC and 2 were still at 65 and 70% yet the the charger was running . Why would this uneven discharge happen? And why would the charging take place ? Cooked Inverter? Any help would be appreciated.​

 

[SamDeleted]

So to confirm, half the batteries are at 0%soc , the other two around 70?

 

[Supervstech]

Your lvd may be set below the point where the bms safeties kick in.
Adjust lvd to above bms settings.

 

[Supervstech]

Pleaseexplain the pictures.

It looks like you have different banks connected to different inverters.

 

[threepets]

Sorry I am having trouble posting pics. The picture with 2 batteries is old. I deleted it ...I hope.

 

[threepets]

I have 4 batteries only and one inverter.

 

[threepets]

Your lvd may be set below the point where the bms safeties kick in.
Adjust lvd to above bms settings.

lvd?

 

[threepets]

So to confirm, half the batteries are at 0%soc , the other two around 70?

That is how I found the batteries charging in the middle of the night

 

[SamDeleted]

Sorry I am having trouble posting pics. The picture with 2 batteries is old. I deleted it ...I hope.

Its never easy lol !


Do not worry , there's some very clever people here that should be able to help (not counting me ? )

 

[wildbillpdx]

Can't tell from the pictures...are both inverter cables connected to the top of the battery bus bars? I remember Will mentioning you might get uneven battery charging unless you connect one to the top and one to the bottom of the bus bars.

 

[Partimewages]

If you have that much disparity in the batteries you may need to charge the whole bank and hold it for a few hours to let it equalize.

 

[Tomthumb62]

lvd?

Low Voltage Disconnect

 

[Balrog006]

I use the MPP LV6548 6500w off grid Solar inverter (CSA) 48v 110vac / (2 units for 220vac )DUAL MPPT solar charger 120A. With 8 - 465w Panels and 4 - Lifep04 51.2v Batteries. I am not Grid connected , but the LV6548 is AC connected to the grid for times when there is no solar and batteries are depleted . …On a couple of occasions(just recently) the batteries have run done and no sun to bring them back so the charger (MPP LV6548)kicked in and charged the batteries back to 100% off the grid by having the LV6548 plugged in to the grid.​

How are you not “grid connected” and “AC connected to the grid”, so the “batteries can charge off the grid”?!?!?

 

[threepets]

How are you not “grid connected” and “AC connected to the grid”, so the “batteries can charge off the grid”?!?!?

I guess you can say I am Grid connected but not Grid Tied. The Inverter has an AC in connection. Which in my case I use a 10 Gauge 2 wire(with a ground wire) extension cord I plug into the wall outlet that connects to my grid breaker box by a 10/2 Romex wire and a 30Amp breaker . In the Breaker box.

 

[threepets]

If you have that much disparity in the batteries you may need to charge the whole bank and hold it for a few hours to let it equalize.

That is exactly what I did. I separated the low SOC batteries and charged them until Voltages were equal(with the separated 2) and then connected them all back together. But with limited sun ,charging was minimal. Is there a way to start Inverter charging manually.

 

[threepets]

Can't tell from the pictures...are both inverter cables connected to the top of the battery bus bars? I remember Will mentioning you might get uneven battery charging unless you connect one to the top and one to the bottom of the bus bars.

Positive 4/0 cable is connected top left Buss Bar, Negative 4/0 cable is connected bottom right

 

[threepets]

Your lvd may be set below the point where the bms safeties kick in.
Adjust lvd to above bms settings.

Is LVD not in the BMS?

 

[Partimewages]

That is exactly what I did. I separated the low SOC batteries and charged them until Voltages were equal(with the separated 2) and then connected them all back together. But with limited sun ,charging was minimal. Is there a way to start Inverter charging manually.

What do you mean "voltages were equal"?

 

[threepets]

What do you mean "voltages were equal"?

All batteries were charged to 52.2v , 52.4v, 52.3 v 52.6v,thats as close to equal as I can get them. State of charge wasn't anywhere near equal. But the next days sunshine started bringing the SOC closer . Now after running my home all day and minimal sun (there was some charging today). The 4 Batteries are now at. 1st 52.90V ,51% SOC. 2nd 51.75V, 52% SOC. 3rd 51.90V 44% SOC. and the forth battery is 51.81V 46% SOC. I am hoping for sun tomorrow.

 

[Partimewages]

All batteries were charged to 52.2v , 52.4v, 52.3 v 52.6v,thats as close to equal as I can get them

You're still in the flat part of the voltage curve at that voltage. They all need to go to 55.2 and be held there for a while. They are likely no where near 100% charged.