harrisonpatm
Member
- Joined
- Jan 5, 2022
- Messages
- 401
Pack is 14s Li-ion, made of tested laptop cells. Each parallel group is made up of 3ea 24p packs, added at different times. Been in service for almost 2 years, no major issues at all.
Last night i went to bed, pack was at 54.5v, .02-.03v cell deviation between pack (about 3.9v per cell), as per my normal usage. Overnight loads are 3d printer, cell chargers, fridge, modem, router, some lights, phone chargers. Not the whole house. Came home from work this morning at 8am, pack was around 52.5v, if I remember correctly. I started charging my motorcycle from my boost converter, which takes my pack voltage and boosts it up to 83v. I checked the powerwall for temperature, it was around 7-8 degrees celsius. I did not notice or check cell deviation at that time. After one hour, I checked again: my BMS had shut off discharging. Packs 1-5 had dropped voltage to 3.0-3.2. The rest were over 4.0v.
What the hell happened? Possibly overnight, but also possibly in the span of just 2 hours, packs 1-5 drained almost completely, while packs 6-14 seemed to have risen to almost full charge.
I'm currently in emergency damage control mode, I've opened up my outdoor enclosure to access the cells directly, and I'm using a hobby charger and alligator clips to charge individual groups. No obvious damage to the cells. No cell fuses seem to be broken, though I haven't laid eyes on every single cell yet. No smoke, no smell of smoke, from shorts or whatnot. Not burnt wires or visable shorts. The enclosure is buttoned up tight in a small sealed enclosure, and if there was any sort of thermal event, I would have easily smelled it when I took off the front panel. No dice.
I will check back as I work on the issue from my end today. Any suggestions for issues to look for are appreciated.
Last night i went to bed, pack was at 54.5v, .02-.03v cell deviation between pack (about 3.9v per cell), as per my normal usage. Overnight loads are 3d printer, cell chargers, fridge, modem, router, some lights, phone chargers. Not the whole house. Came home from work this morning at 8am, pack was around 52.5v, if I remember correctly. I started charging my motorcycle from my boost converter, which takes my pack voltage and boosts it up to 83v. I checked the powerwall for temperature, it was around 7-8 degrees celsius. I did not notice or check cell deviation at that time. After one hour, I checked again: my BMS had shut off discharging. Packs 1-5 had dropped voltage to 3.0-3.2. The rest were over 4.0v.
What the hell happened? Possibly overnight, but also possibly in the span of just 2 hours, packs 1-5 drained almost completely, while packs 6-14 seemed to have risen to almost full charge.
I'm currently in emergency damage control mode, I've opened up my outdoor enclosure to access the cells directly, and I'm using a hobby charger and alligator clips to charge individual groups. No obvious damage to the cells. No cell fuses seem to be broken, though I haven't laid eyes on every single cell yet. No smoke, no smell of smoke, from shorts or whatnot. Not burnt wires or visable shorts. The enclosure is buttoned up tight in a small sealed enclosure, and if there was any sort of thermal event, I would have easily smelled it when I took off the front panel. No dice.
I will check back as I work on the issue from my end today. Any suggestions for issues to look for are appreciated.