Hi there!
name's Alex
Just finished my powerwall project, which I have started in the end of february.
All cells were harvested from used/bad e-bike batteries. Most of the time, about 2-3 cells in each pack were bad (high inner resistance or very bad capacity), the rest usually was just fine
I tested the cells using 5 Opus chargers in parallel.
In total, I've tested about 2300 cells, some were bad, some mechanically damaged. Some got hot during charge (some sanyo, but also some panasonic). Of course, I threw out all these bad cells. Still, I've ended up with 1960 good cells, the average cell capacity is 2100 mAh. My cell configuration is 14s140p.
The wiring of the cell holders was straight forward. I used 1.6 mm copper wire for the bars and 0.2 mm tinned copper wire for fuses (double fuses + and -)
The Powerwall is hooked onto a PIP 5048MS (PF1). Charge end voltage is 4.09 V / cell and discharge end voltage is 3.3 V / cell. Power is coming from a 4.5 kWp solar array.
I'm not using a BMS. Each cell block has a little voltage readout and a passive balance board that kicks in at 4.1 V (2A current).
I have found a software, that automatically calculates the pack layout for the 1960 cells. This worked so well, that the voltage drift between the cells is minimal. Deepest discharge so far was 3.55 V and the difference between each pack was less than 0.02 V. I didn't expect that, but of course I'm happy
Also when recharging, the balancer modules did not yet get active. All packs equally charge up and perfectly end up at 4.09 V without the need for balancing (yet).
I'll see how the pack behaves the next weeks / months.
best regards,
Alex
name's Alex
Just finished my powerwall project, which I have started in the end of february.
All cells were harvested from used/bad e-bike batteries. Most of the time, about 2-3 cells in each pack were bad (high inner resistance or very bad capacity), the rest usually was just fine
I tested the cells using 5 Opus chargers in parallel.
In total, I've tested about 2300 cells, some were bad, some mechanically damaged. Some got hot during charge (some sanyo, but also some panasonic). Of course, I threw out all these bad cells. Still, I've ended up with 1960 good cells, the average cell capacity is 2100 mAh. My cell configuration is 14s140p.
The wiring of the cell holders was straight forward. I used 1.6 mm copper wire for the bars and 0.2 mm tinned copper wire for fuses (double fuses + and -)
The Powerwall is hooked onto a PIP 5048MS (PF1). Charge end voltage is 4.09 V / cell and discharge end voltage is 3.3 V / cell. Power is coming from a 4.5 kWp solar array.
I'm not using a BMS. Each cell block has a little voltage readout and a passive balance board that kicks in at 4.1 V (2A current).
I have found a software, that automatically calculates the pack layout for the 1960 cells. This worked so well, that the voltage drift between the cells is minimal. Deepest discharge so far was 3.55 V and the difference between each pack was less than 0.02 V. I didn't expect that, but of course I'm happy
Also when recharging, the balancer modules did not yet get active. All packs equally charge up and perfectly end up at 4.09 V without the need for balancing (yet).
I'll see how the pack behaves the next weeks / months.
best regards,
Alex