Great thread. I can’t remember why I only skimmed through this before, maybe because it was before my first battery charging and cycling and I didn’t understand everything here. This thread deserves more replies.
So, as you’ve found, the voltage drops very quickly around the 140V point and it’s difficult to catch it at the desired voltage when you’re discharging manually. It’s a lot of checking. This is why I started the Simple Arduino Discharger project so you could connect it up and walk away. I reckon if you’re competent enough to build an OlRowdy grid charger you’ll be competent enough to to build a SAD discharge controller.
I’m also still of the opinion that the first discharge on a badly out of balance pack should only be to 140V. Maybe even higher on a pack triggering the IMA light. The logging from my first SAD discharge showed that the first cells were dropping out at this point. Despite opinions on here, I don’t like holding cells reversed, even at low current. If you were to shut off the discharge at this point, fully recharge and repeat, the next discharge will be a lot cleaner and much more even throughout the pack. This is because you’ll have significantly improved the performance of the weakest cells in the pack by reversing the memory effect and at least boosted the performance of the ones following closely behind them.
So, as you’ve found, the voltage drops very quickly around the 140V point and it’s difficult to catch it at the desired voltage when you’re discharging manually. It’s a lot of checking. This is why I started the Simple Arduino Discharger project so you could connect it up and walk away. I reckon if you’re competent enough to build an OlRowdy grid charger you’ll be competent enough to to build a SAD discharge controller.
I’m also still of the opinion that the first discharge on a badly out of balance pack should only be to 140V. Maybe even higher on a pack triggering the IMA light. The logging from my first SAD discharge showed that the first cells were dropping out at this point. Despite opinions on here, I don’t like holding cells reversed, even at low current. If you were to shut off the discharge at this point, fully recharge and repeat, the next discharge will be a lot cleaner and much more even throughout the pack. This is because you’ll have significantly improved the performance of the weakest cells in the pack by reversing the memory effect and at least boosted the performance of the ones following closely behind them.
