Karnallie

The left and right images are at different times - look on each image there are 2 LCDs: one top and one bottom which are the 2 battery packs. As you can see the Pack Voltages are within 50mV of each other

Hi all, I have 2x 16s 5.1kWh 48V LiFePO4 battery packs that use Seplos v2.0 BMS to my understanding. The system was disconnected for a few months during renovations, and reinstalled 4 months ago. Both battery packs were discharged quite low while stored, so they were individually charged back up to 100% SoC before being reconnected in parallel to the inverter. Recently I started noticing that the battery packs are NOT tracking each other's SoC %, but rather just Voltage - which leads me to believe the parallel connection is not setup correctly. After both being charged up to 100% and discharged during the day, I notice a ~10% difference in SoC: Top is the master battery 0, and bottom is parallel slave 1 Does anyone have knowledge of the parallel function of Seplos BMS and whether I should expect the SoC or the PackV to track one another? Is there perhaps a communication issue between my battery packs? Kind regards, Francois

No thanks to your AI response

So I was mistaken - enabling time of use the battery does get discharged to the loads down to the % specified. Without time of use enabled the batteries do not discharge other than to the inverter or with grid off. I seemed to recall that with time of use off and grid charge disabled the batteries would discharge down to the values specified, but my system was offline for a few months (construction) so I forgot. Parallel setup is working fine now with time of use setup, even with different firmware. I used to use Solar Assistant to toggle on/off the time of use depending on immenent load shedding and the battery soc, but that would have depended on the batteries actually discharging with ToU off. So not sure how that used to work anymore. Thanks for the info about the Bms data on the secondary inverter - that is reassuring. I am not seeing other settings explicitly syncing to the slave inverter though, eg ToU enable/disable, grid charge, battery charge/discharge currents, zero export. Should I expect those to be the same on the slave inverter when changed master side, or do you still configure them explicitly on the slave as well? That might be where exactly matching FW comes into play.

I seem to be having the same issue: Upgraded to 2x Deye 5kW inverters, old one Master (01), new one Slave (02). Batteries are connected to Master using CAN cable. PV is charging the batteries fine and also supplying to the loads (essential and non-essential), but the batteries are not being used for loads. When PV is gone the batteries discharge at around 100W (I assume powering the inverter(s)), but Grid is used for loads: Master inverter is reporting BMS values correctly, but slave not. I assume that is since it is not directly connected to the batteries? Or should I expect the Slave inverter to report the same values from the parallel connection? There are no (parallel) errors reported by either of the inverters. The batteries are set to discharge down to 20%. The slave inverter has newer firmware since it is 2 years newer, and it is the Deye 5kW "SA version" while the older one is not. Should the master inverter's FW be updated somehow?