PVman

Thanks for the links, much appreciated. In the meantime I've chatted with Deye Europe Support about the SoC drift issue. My cell voltages are all OK. I also discharged them to 5% in case one of them was a bit lazy in providing current, but that led to a 20% drift the following night. After some tests, the problem is due to low load conditions and Deye support confirmed that under these circumstances only one battery will provide power (usually the master) and if more current is needed the second battery will kick in. If both batteries get activated they will remain active and eventually will balance voltages. I did an all night low load test to see how far one battery will discharge before cutting out. I can confirm that the master discharged to 52.0V (~58% SoC) and then the slave battery took over and master was set to idle. They eventually balanced out each other the following day when the sun came up. Deye also update by BMS firmware to V2.0.0.B and inverter HMI to 0000-C375. They said that 40% drift is too much and 10% is OK. The drift is still there after the upgrade, but now the batteries balance out charge within a couple of hours if they drift to far apart which is an improvement It appears the BMS logic is to discharge batteries one by one which actually suits my needs since i plan to fit 9 for a total of 45kWh, but i will be using energy only from one or two batteries daily and use the rest twice a week to charge my EV at night.

Hi, Can you please share your latest LVESS software? Cann't find it and I want to have it in my library in case i need to debug my batteryes. My story is below. I recently bought two Deye SE-G5.1 Pro B batteryes (AA56, firmware 2008), tied them up to a Deye 8kW inverter, very easy to setup and all is fine with them. Can handle a 3kW load easily and have been completly off-grid for the past two days. So far so good. Now, by the third battery cycle i noticed that they discharge unevenly, the first day was like 1% difference in soc, thats ok, the second was 4%, got my attention, third day 9%, got me alerted. Today i drained them all the way to 5%, fully charged on PV and my house consumption was idling 200 ish watts (around 4A from batteryes) after sunset. At 9pm the soc difference was 19%. One battery was at 53.3V and the other at 53.0V. Checked status in Solarman and to my surprise only one battery was discharging (MOS state 0031), the other was doing nothing (MOS state 0021). I started a 2kw outdor heater and the idling battery started to provide power, more amps than the other to catchup, and has been in dischargind state ever since regardless of AC loads. I allready wrote to Deye about it yesterday, got no response yet, but this behaviour does not sound good. It seems on light AC loads the batteryes can not work in parallel. The BMS'es seem to be comminicating and balancing fine on high loads, but this light load condition after a full charge is something weird. I bet Deye never tested it. What are your thoughts, anyone noticed this on their systems?