New Homegrid battery w/Sol-ark. Charging question

[dsimonl]

I have a new Sol-ark 15k and Homegrid 5-stack (500ah) LifeP04 battery. They are connected together with closed-loop communications. Charging voltage is set by the BMS at 53.2V. As soon as charging stops, voltage drops rapidly to 49.9V, but shows 100% SOC. Is that normal? I don't have a load on the battery yet, so no charge/discharge cycles.

 

[Lt.Dan]

If its LiFePO4, them IMO, 53.2v is not fully charged. Where did you find the 53.2v spec?

 

[dsimonl]

It is in the Homegrid spec sheet, and is what the BMS programmed the inverter settings to when they started communicating with each other

 

[dsimonl]

I can't over-ride any of the settings unless I unplug the CAN-Bus connection.

 

[dsimonl]

I just noticed they have an new spec sheet published. This one has the charge voltages even lower! Back to my original question. Does 49.9V at rest seem unreasonable based on the charge voltage?

 

[400bird]

If its LiFePO4, them IMO, 53.2v is not fully charged. Where did you find the 53.2v spec?

It could be a non-standard 15s, vs the standard 16s.

I have a new Sol-ark 15k and Homegrid 5-stack (500ah) LifeP04 battery. They are connected together with closed-loop communications. Charging voltage is set by the BMS at 53.2V. As soon as charging stops, voltage drops rapidly to 49.9V, but shows 100% SOC. Is that normal? I don't have a load on the battery yet, so no charge/discharge cycles.

Lifepo4 charges up to 3.5-3.65 volts per cell. Once charging stops, that quickly relaxes to roughly 3.4 volts/cell or about 51 volts if your battery is 15s.
50 volts is 3.33 volts per cell that doesn't seem out of normal. What is quickly? 5 minutes? 90 minutes?

 

[dsimonl]

Thanks for the reply. Probably an hour. I'm thinking the BMS is probably not calibrated, as the battery is new. Maybe with a few charge/discharge cycles it'll learn the base voltage and SOC

 

[400bird]

It's Lifepo4, this is pretty normal if the battery is 15s.

They battery is going to live at 3.2-3.4 volts/cell.
With that small voltage window you can't use voltage to get SOC, outside of the top and bottom 10-20% when the voltage really starts to the move.

 

[dsimonl]

Much relieved! Thanks very much.

 

[Tpilgeram]

Yes HomeGrid Stack’d is 15S so the voltage makes sense. Do you have any issues with Charge limits? I never see my BMS allow more than 20 amps per module (80 amps total for my 4 module system) even though published limit is 300). HomeGrid support has been useless for months on the issue and have no answers. Discharge seems to work fine. It’s just the charge limit from the BMS.