Recovering 'Fully'Discharged Tesla 100kWh Packs

NiallDarwin

NiallDarwin

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May 12, 2018
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I have purchased two flood-damaged Tesla SP100D cars. Their history is as follows:

They belonged to Tesla's Sydney store and were parked in the basement carpark. There was a burst watermain and the cars got flooded with clean (potable) water. They were drained and dried but comuncation with the battery could not be achieved. So the technicians did a discharge on them before sending them out to auction as flood-damage salvage cars.

I got this one step removed from someone who worked on them so I think its pretty accurate. I believe:
  • They were only flooded overnight (I do not know to what depth).
  • The discharge was a discharge to 0V. I hope not but this is my fear.
  • They were discharged around December/January and so have been flat for a while.
Two main questions:
  1. Does anyone know anything about the procedure for discharging a pack in this situation? Does it absolutely flatten it?
  2. Has anyone encountered this before and made attempts to recover the pack/modules/cells? If so, how did it go?
I'm not banking at all on being able to use them but if there's anything useful I'm all about reuse before recycle :)
 
If they did a complete discharge there must be a way for them to add a load for a period of time, before they subsequently remove it after "discharge" was complete. They may have been able to do this from the charge port.

If they left a shorting / discharge bar in place then this might be an issue. If they have been discharged to near zero, either way the residual load (BMS etc) that is conected to the packs may have drained whatever charge was left. Consider the pack will have 0 volts...

All that said ... I had some 18650 cells in a box from laptops last used 10 years ago, well discharged and then some.... granted they only recovered about 50% capacity but I was quite impressed they had anything at all. So with that extreme in mind I would expect the cells should recover to a useable form vs recycling.., just depends on how much capacity they have.. Best case they will recharge fully....
 
Thanks completely.

I know how to get the contactors to close and so I can put a voltage onto them and see if a charge goes in.

I am pretty certain that the BMS is powered by the car's 12V. The 12V is charged from the main pack but (I believe) this cuts when the main pack gets too low. So hopefully there's been no parasitic load on it.

I hadn't considered the possibility of them having left a shorting bar in place. I sure hope not! To do this they would have had to defeat the battery's contactors which are normally open without 12V. I wouldn't put it past them though.

Time will tell I suppose-I'm at least a month away from getting my hands on them.
 
Are they currently in Sydney.
If so would you like someone to look at and/or do anything to them?
I am iin Sydney and might be able to help somehow?
 
You know to be honest i doubt they would have discharged them to 0V.
Heres my thinking. The connectors on the out side of the pack are connectors after the bms. So putting a load onto there would only drain the pack the the cut off voltage, around 2.5v per cell, depending on the size of the load (has to be huge for a pack that size) the cells would then have rebounded quite a bit and would now be sitting at about 2.8v (from experience). There is not that much energy left in there now so thats usually all that needed.

I doubt there are any high voltage connectors on the outside of the pack that bypass the BMS because that would be very dangerous.
If they would have done a 0v discharge then they would have had to remove the pack and then open it up to get to connectors that are before the bms. I doubt tesla would rip open the water tight pack and then sell it... thats very dangerous and unprofessional. If they would have opened iit it would go straight to a certified recycler so there is no chance of property damage or harm to people.

Bit even if they would have done a discharge before the BMs somehow you might still be in luck. I once had to drain an ebike pack from work to kill it. We have a load that does about 8A on a 42v pack when its full, dropping to about 6A when goltage reaches cutoff. (Forgot the math to calculate what ohms that resistor has) I left it plugged in for 7days! The voltage was 0.00V
I removed the load and neasued the voltage the next day, it was at 2.25V. Thats 0.225v per cell. Over a year later i revived those cells (they were sitting at 0.21 then) and they later in tested at 2600mah (original 2900 and they were used so no clue what capacity they had left before the discharge).
Yes the internal resistance was higher and 5 of the cells were dischargers but these cells still work today!

My point with this is that if they had opened the pack and discharged it i doubt they have left the load in there for longer then needed, so the pack would have bounced back up a bit.
Like others have said though if they left a resistor attached then you might be screwed.

My 2 cents :)
Let us know how it goes!
 
Let's not forget that these were flood damaged. Wet enough to damage some part of the communication system. I dont know how well Tesla packs are sealed, but I saw another post on this forum with rusty Tesla cells that only had exposure to humidity. Deep discharge might not be your biggest problem.
 
Dallski said:
Let's not forget that these were flood damaged. Wet enough to damage some part of the communication system. I dont know how well Tesla packs are sealed, but I saw another post on this forum with rusty Tesla cells that only had exposure to humidity. Deep discharge might not be your biggest problem.
Click to expand...

Agree. Even if the water was distilled water, it still would have dissolved any available salts. If that water did get inside, and on to the cells themselves, I would give them a miss. As any dissolved salts will have been left on the cells themselves.I have also read that Tesla cells lack the CID and PTC (perhaps someone else could verify or disprove this)that normal cells have. This would be a huge problem should the cells rust and short circuit.
 
I thought the model S pack was relatively well sealed keeping an eye on this one, curious to see the outcome. Goodluck OP.
 
Crimp Daddy said:
I thought the model S pack was relatively well sealed keeping an eye on this one, curious to see the outcome. Goodluck OP.
Click to expand...

Me too, plenty of packs that had no intrusion after quite a bit of time in the water.
Pretty sure they say its waterproof, at one stage every seal gives up though...
 
Any cell that sat at 0v for any extended period of time is done for in my opinion. They get damaged lose capacity and whatnot.
 
hbpowerwall said:
Hit up Bruno in Sydney https://www.facebook.com/bruno2bari he's good with fast things (if in Sydney)
Click to expand...

Ha ha, yeah I know Bruno. This is him messing with one of my wrecks before it hit NZ:

Thanks for the Sydney offers. Its going direct from auction house to shippers to NZ so I can't take you up on any of them

Geek said:
I have also read that Tesla cells lack the CID and PTC (perhaps someone else could verify or disprove this)that normal cells have. This would be a huge problem should the cells rust and short circuit.
Click to expand...

I'm pretty sure they lack the PTC. Their connection to the busbars via thin 'fuse' wire is essentially an external version of this. I'm don't know about the CID.
Good points though.
 
OK, massively delayed update, sorry.

Both cars had about 50% SOC in the packs so the rumours about Tesla having flattened the flooded car were very wrong. They had seemingly unplugged a very well hidden interlock sensor in the charger meaning the car wouldn't let the HV contactors close. Fixed that and a couple of other things and the car is pretty close to working. Unfortunately the NZTA (New Zealand Transport Authority) rules about getting flooded cars on the road have changed from fairly easy to fairly horrible so I don't think the car will ever be road legal in NZ. I'll either try and sell it as a track car or build the bits which make it ludicrously fast into my merely stupidly fast Tesla...

Thanks to all who pitched in with positive suggestions :)
 
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