Just so we are all on the same page, what EG4 battery do you have?
I purchased six EG4 LifePower4 batteries from Signature Solar six months ago. One battery (#5) has always been the redheaded step child in the stack. Four cells in the battery would not charge above 3.38 volts while charging the battery to get cells to 3.45 volts at which the BMS will start balancing and SOC will reset to 100%. I am using an EG4 Charge-Inverter who's output is connected to the bus bars (via a Victron shunt) in the rack.
Last Sunday (06/09/2024) sent an email to Signature Solar requesting permission to open the battery and individually charge each of the four cells.
As of yet no response.
Late Monday I pulled the battery from the rack, placed it on my workbench, opened it up and using a variable 0-30VDC power supply charged each of the cells to 3.5 volts while monitoring the battery with the BMS_Test software. Each cell did charge to 3.50 volts and all is well.
I now have a 0-60VDC power supply set to 55.5 VDC charging the battery while allowing cell balancing and all cells are within 11mv (wish it were lower). The four offending cells did accept a charge, held the charge (which is a positive sign) and are now (at least appears so) playing well with the others. I do need to place a load on the battery to get SOC down to say 75% then re-charge and hopefully the four cells will charge right along with the others.
Trial and error along with patience. We invest money in this stuff but unfortunately it is often not plug-n-play.
I did purchase the 0-30VDC variable power supply (one with over current protection) from Amazon.
In addition a digital multimeter that will display three digits to the right of the decimal point will be extremely helpful so you can observe/measure to 1 millivolt resolution.
