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Tesla Model 3 Module Issue

Csecrist12

New Member
Joined
Dec 10, 2020
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I am having some issues with a module from a Tesla Model 3 pack. I have 4 modules, (2) 23S and (2) 25S modules. Both 25S modules and only (1) 23S module are in well balanced condition. I am concerned with the 1 off-module.

So the issue is, I can see the module voltage at the ends of the module (it shows around 50-52V ish) which means the cells are low. I figured as they haven't been charged in a few years and I left them fairly lower for storage purposes. I went to each brick and everything was checking out except for 1 set. The 1 set shows a 0V, completely flat. I tried adding a PSU to the brick to bring it up close to the surrounding bricks and nothing happened except for the voltage coming up and staying at 0.18V. It wouldn't go any higher even though I was pushing 3.15A into that brick (as high as my PSU will go). I used a thermal

camera to see if I could find maybe a ground or short, but nothing lit up as I expected.

Any direction or idea I can go to revive this module?
 

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You have a dead cell group in one module.

LFP discharged below 2.0V will degrade. Even if you can restore function, the cells will have notably higher internal resistance and likely underperform substantially.
 
Would it be best to look for a replacement module to complete this pack or would it fair to try and replace these cells? I know replacing the dead brick is extremely difficult and cumbersome, but I have witness others do it.
 
LFP discharged below 2.0V will degrade.
It's the NMC pack.
Csecrist, stop trying to charge NMC cells at 0V, they are dead and you can cause catastrophic event playing with those.
How are the wire bond fuse under each cells of this 0V section. From your picture it look like you scrape all the wire bond who connect cells to busbars.

 
The wire bonds looked actually really good. There was only 1 or 3 fuses broken off, but other than that, nothing was fried off that I could see.
 
would it fair to try and replace these cells?
You have the pack in hand, so you can clearly see how glue/fix are the cells in the white support. The cells are really hard to remove.
Then add the fact that busbars and wire bond are brittle and it look, to me, those module are impossible to repair.

What was your plan for those modules? HV inverter?
 
Yes, I have experience in tearing one down, not an easy task at all on the teardown, let alone retaining critical connections in the middle of the pack.

And yes. I have a Solis High Voltage inverter rated for 500V Battery input. I have 2 of these Tesla Model 3 packs and 2 Inverters, so it was a perfect match, 2 of the exact same batteries matched with 2 of the exact same inverters.

I do have a buddy I sold a pack to that he is willing to swap the 23S module with me. Would that be a decent solution?
 

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