Do I have Enginer PHEV battery problems?

Hi Sielerts –
Thanks for the post on the way the BMS works. I must have missed that when I was reading through the documentation. Indeed, from your description it seems to only be a management system and not an active balancer. As you noted this is a much more difficult problem to handle. I would like to install one of the new active balancing systems after they are released by Enginer to see if it makes a difference. I’ve had my system for about 6 weeks and I find that cells 1-4 are continuously dropping lower than the other cells. This causes the BMS to turn off the system while other batteries are still reading OK on the voltmeters. My solution is to put a power supply on them about once a week to bring them up to the rest of the cells. After the battery pack is discharged to where the red light comes on, I turn on the digital voltage monitors to read the cells, cells 1-4 were down to 3.12 volts tonight. Perhaps they are lower than that under load and recover by the time I look at them. There is some good news here as all 4 of these cells read exactly the same voltage. The remaining 12 cells are between 3.25 and 3.29 volts. I am doing this extra balance on cells 1-4 about once a week, so I’ve now done it twice since I started this post and tonight is the 3rd time. I usually try to stop after putting 100 Watt Hours into the 4 cells as I don’t want to push the cells too hard. That makes them higher than the lowest cell but lower than the highest of the remaining 12 cells. Hopefully this approach will get me to the nirvana of a well balanced pack soon.