Tuesday, June 20, 2023

The challenge of charging Tesla packs.

The problem:

When connecting LiPo cells in parralel, massive equalisation currents can flow, especially if the voltage differs significantly. https://www.rcgroups.com/forums/showthread.php?2297114-Equalizing-two-LiPo-s
It's been a bit of a 'pain' to charge 16 packs to the same voltage. Once I got to the 16th pack, the 1st one was out of whack again. 

The solution:

Instead of using resistors, I've come up with a different idea, using diodes.

The diodes will stop the cells discharging into each other, but will allow charge to in from the charger. There will a slight voltage drop from the diodes, but I can turn the power supply up to match the drop in voltage. To compensate from the drop in voltage, I have ordered Shottky diodes, which should have a lower drop across them.

I'll let you know how it goes. There have been several suggestions that diodes are not very reliable, and might fail-shorted. If they do, they will most likely burn out, like a fuse.

1 comment:

  1. It went excellently, as expected the diodes did work correctly. I did 'split' the packs, so I had 16 diodes, rather than 8. I got to within 0.01V/pack. The diodes did get slightly warm. I was using a 350W power supply, and initially did not realise that a single diode (the one protecting the pack with the lowest voltage, would be taking the full power from the power supply on it's own.