Battery charging trouble - cells are good, tried everything, no luck!

Sep 18, 2023
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Have tried almost everything people recommend with no luck... so thought I'd see if there are any other tricks left...

Took my P4 out of storage, with all three batteries charged to around 60%. Tested the batteries, they all turned on fine with 2 or 3 leds. The next day I try to charge them and that's where the fun begins.
Two of them didn't light up at all (even when just trying to turn them on), the other lit up but had trouble charging.
I opened them up:
- one battery, one cell was dead and wouldn't charge, so that's dead
- the other two batteries, I charged up with a NiMh charger to around 3.8v/cell (no major imbalances between cells)
- shorted the reset pin which made the LEDs turn on as expected
- now the batteries turn on and stay on, showing one solid LED (I find this strange as one of them has just over 15v, I'd expect more LEDs)
- however, when I plug them into the charger LED1 flashes quickly around 15 times, then turns off, then repeats and so on
- I also tried what many recommend: press power button once, leave for 5 minutes, plug into charger and leave for hours. No luck, LED just flashes quickly

Can't find many references to this specific symptom (LED1 flashing many times quickly)...

Any idea what this means or what I can do about it?

Any idea what this means or what I can do about it?

You've triggered Permanent Fail flag in the BMS.

Get a cheap USB-to-I2C interface, or Raspberry Pi.
Use free software for DJI batteries to talk to the battery, confirm its status and lift the PF flag.

I'm not sure if the BMS in Ph4 stores the PF flag in non-volatile way (in order for that to happen, the PF functionality needs to be enabled during manufacturing).

For Inspire 1 batteries, it is enough to disconnect the control board for a few minutes to clear the PF - the function is not enabled.
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Don’t know where you are or if you want to pay a little to fix them.
I found this guy- Erik Navarro
(815) 200-1247

South suburban Chicago area. He reconditioned 4 of my P4P batteries. If it’s simple, $50, if a bit more work, $65.
You can mail them to him.

This was a couple years ago and they were like new. Way cheaper than a new one
Great & fast service too.
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