I posted this on another forum but I see there are some Pylontech Engineers on this forum. Please see my current issue I am facing below with SegenSolar / Pylontech Batteries US2000b Plus models.
I have a 6 year old installation in a 4 x 5kW Axpert Inverter setup as attached with 20 x Pylontech US2000b Plus (And some new US2000C Top batteries in Cabinets for failed US2000b Plus Replacements). US2000b Plus Batteries started failing 1 or 2 at a time since 2 years ago with 900-1100 cycles on the batteries. Initially when installed in 2017 Pylontech approved the 53.2v Float/Absorption charge settings for the 10 year warranty and it was submitted to them by installer. 2 Years ago they replaced 2 batteries. The voltages on inverters was then adjusted by installer due to 2 batteries failing to a lower voltage 52.7v Absorption and 52.4v float, according to installer Pylontech’s new recommendation is lower voltages to prevent overvoltage which still indicates the batteries are charged 100% full after the settings changed, so voltages seemed fine. Earlier this year another 2 batteries started to discharge faster than other’s and Pylontech did not replace it and attributed it to overcharge voltages. How can 2 batteries in 2 cabinets fail out of 20 (4 x 5 Strings of batteries, 5 batteries per inverter) Insurance declined physical or electrical damage claim and attributed it to wear and tear. Pylontech should cover battery usage (Wear and Tear) for 10 years correct ? If warranty not covering these batteries and insurance not covering it under electrical/surge damage does anyone have a resolution here please ? Last week I noticed another battery discharging faster than other’s and since Pylontech is not replacing I opened it to check if swollen. It was swollen as attached as the previous ones which they did not replace so I did not care I if voided the warranty by opening it. Today another US2000b Plus started discharging faster than other’s. Some sample monitoring screenshots attached. The 10V Battery on the left side of image attached was swollen, on other 2 batteries the 30V right side was swollen. Totally random and different inverters on these batteries. All battery cycles since installed 6 years ago are less than 1200 Cycles. Since day 1 battery monitoring was done (1st ICC then then swopped to Solar Assistant), battery voltages never exceed 53.2v and the past year never exceeded 52.7v after lower voltages set on inverters. Cut-off voltage done before reaching minimum voltages around 20% battery remaining on cut-off but low voltage according to Pylontech warranty replacement was not the problem, overvoltage was. Battery temps as per 3 months graphs indicates battery temps are within suitable temp ranges. I can only monitor 8 batteries at a time due to US2000 Plus limitations but I swop the monitoring console cable to a different set of batteries every 3 or 4 months to check if batteries still good. So 6 Batteries failed out of 20 and Pylontech attributes this to overvoltage and only 2 replaced. 1 I opened so voided warranty and the one I checked today not opened yet. Any ideas since I will rather not recommend Pylontech for honoring their 10 years warranty at this stage. I also queried them dates of which overvoltages occured but they just ignored me.
