Hi. I have created the PV system described in the title and it seams I have a charging issue.
Note I have series connected 4 LiFePO4 batteries, each one has its own internal BMS.
Since there is no BMS communication with the inverter I used USER2 settings for Growatt and specified the charging curent 40A (0.2C), charging and floating voltage to 4x14,4V (57.6V), cut off voltage to 44V.
Before connecting the batteries to the inverter I have connected all 4 in parallel for 24h to balance them as much as possible when each one had 13.4V.
Finally, I have connect them in series to the inverter and start charging base on the USER2 settings.
After sometime, the charging stopped when the battery system has about 75% (displayed in mobile app). Actually, each about 20 sec the inverter tries to start charging then stops. I see that on the inverter display and on the clamp ampermeter connected to the battery DC cables (reading sometimes ~5A then drop to 0A).
Since the inverter displays 75% battery SoC I guess it estimates this based on the sum of the voltages and starts charging but something (maybe one of a BMSs) stops it. I have disconneted all 4 batteries and measure after some rest these values:
* 13.91V,
* 13.91V,
* 13.40V,
* 13.53V
I suppose the BMS of one of the 13.91V battery disconnects while the inverter starts charging.
Is that correct my assumption? Can someone please explain what happens? Any luck to fix that or a solution?
Regards.
Note I have series connected 4 LiFePO4 batteries, each one has its own internal BMS.
Since there is no BMS communication with the inverter I used USER2 settings for Growatt and specified the charging curent 40A (0.2C), charging and floating voltage to 4x14,4V (57.6V), cut off voltage to 44V.
Before connecting the batteries to the inverter I have connected all 4 in parallel for 24h to balance them as much as possible when each one had 13.4V.
Finally, I have connect them in series to the inverter and start charging base on the USER2 settings.
After sometime, the charging stopped when the battery system has about 75% (displayed in mobile app). Actually, each about 20 sec the inverter tries to start charging then stops. I see that on the inverter display and on the clamp ampermeter connected to the battery DC cables (reading sometimes ~5A then drop to 0A).
Since the inverter displays 75% battery SoC I guess it estimates this based on the sum of the voltages and starts charging but something (maybe one of a BMSs) stops it. I have disconneted all 4 batteries and measure after some rest these values:
* 13.91V,
* 13.91V,
* 13.40V,
* 13.53V
I suppose the BMS of one of the 13.91V battery disconnects while the inverter starts charging.
Is that correct my assumption? Can someone please explain what happens? Any luck to fix that or a solution?
Regards.