FoxESS Community - Owners & Installers Forum

Hello

I had a Foxess cube battery (EC4100 V2, 8 kWh) which I had extended with an extra slave last week (now 12 kWh). Was working fine before, but now notice from the SOC data that the battery is steadily charging up to around 80% (4% per 5 mins) then suddenly jumps up to 100% 5 minutes later. Same thing happens during discharge which declines steadily down to ~25% then jumps in 5 minutes down to 10%. See attachment. It's almost like there is 15-20% of battery capacity it expects to be there which actually isn't. I thought it was a battery balancing issue which would sort itself out, but been 5 days like this now. It doesn't appear to be using the full capacity as I would expect 10.8 kWh to go in on forced charge overnight (10-100%), but only 9.5 kWh is going in. Also noticed battery is dropping down to 6-7% at night despite having minimum SOC set to 10%.
Any ideas on what could be causing this and how to solve it would be much appreciated.

Thanks

I had a similar issue with my EC4800's after adding extra slave units.
I wasn't getting the sudden changes at each end of the charge as you are but mine were giving me a lot less calculated capacity (~80%/18.5kwh of the stated 23.3kwh) when performing forced charges overnight so seemed to be just missing/hiding the rest.
I left it to carry out its battery balancing for ~6 weeks before contacting Fox support.
They updated the firmware to the latest v1.10 and then, over the course of the next week, this seemed to give it that 'extra bit' so it is now ~90%/21kwh.

Thanks. I'll contact Fox support and see if they can push through any firmware updates.

My batteries are charging OK but I have recently had the same issue of the minimum SOC dropping to 6-7% overnight despite being set at 10%. Should I be concerned? In case it's relevant the batteries are insulated so temperature is normally 22-25 degrees overnight.

3 x Mira HV25. firmware version.1.0
BMS HV25 firmware 1.004

Jim O'S wrote: ↑Sun Mar 03, 2024 11:05 am My batteries are charging OK but I have recently had the same issue of the minimum SOC dropping to 6-7% overnight despite being set at 10%. Should I be concerned? In case it's relevant the batteries are insulated so temperature is normally 22-25 degrees overnight.

3 x Mira HV25. firmware version.1.0
BMS HV25 firmware 1.004

Same batteries and firmware here and this has happened to me too. What usually happens is the BMS eventually notices and charges at about 1.2kW for half an hour or so to bring them back up.

I've just raised a service ticket on Friday with Fox to get the firmware updated to the newest as 1.004 master and 1.00 slave is very old. Hopefully it'll help.