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Advice needed on waking up Model 3 [salvage car sitting for 1 year unplugged]

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
11,400
13,236
Riverside Co. CA
Why did you let it sit for so long with out charging?

The answer to that question is in another thread this OP started, here:

 

Gauss Guzzler

Safety Score = 7
Dec 27, 2020
660
850
Thousand Oaks, California
I strongly believe Tesla has through about the car being left unused for prolonged periods and they have built in a protection feature which shuts down the power consumption once it reaches a critical level. The main battery shows about 230 volts when measured with a multi meter at the terminals. See the video here -
230V is pretty low, I wonder if that guy actually succeeded? I don't know the minimum voltage for Tesla's chemistry but it's surely around 3V/cell and that Youtuber is at 2.4V/cell. Have you measured your pack?

When the voltage gets that low it can damage the cells in a way that makes them dangerous to charge so I suspect the charging system is just refusing to try. You can manually charge the pack up to 300V, manually balancing it as needed and then see if the car will acknowledge it, but if you don't have the equipment to manually charge a 300V battery handy, you might not be the right person for the job. I recommend contacting a battery rebuilder like Gruber Motors to discuss your options.
 

Frank99

April 2018 Model 3 LR RWD, EAP, FSD
Apr 7, 2016
366
492
Arizona
I think Gauss Guzzler has it right. The pack has fully shut down to try to save itself. There’s likely an “undervoltage cutoff” circuit that’s doing this, that isn’t under control of the computer.
It’s likely your only possible resolution will come from applying a low current (1A perhaps) 300V supply to the battery and waiting until the battery voltage comes up. If the car can connect to the battery after that, hallelujah, the bms system should bring it back up and balance it and life should be good. If it doesn’t, then likely only Tesla can reset the low voltage cutoff.
 

stopcrazypp

Well-Known Member
Dec 8, 2007
11,111
6,247
230V is pretty low, I wonder if that guy actually succeeded? I don't know the minimum voltage for Tesla's chemistry but it's surely around 3V/cell and that Youtuber is at 2.4V/cell. Have you measured your pack?

When the voltage gets that low it can damage the cells in a way that makes them dangerous to charge so I suspect the charging system is just refusing to try. You can manually charge the pack up to 300V, manually balancing it as needed and then see if the car will acknowledge it, but if you don't have the equipment to manually charge a 300V battery handy, you might not be the right person for the job. I recommend contacting a battery rebuilder like Gruber Motors to discuss your options.
The absolute lowest cutoff I have seen for lithium ion is 2.5V per cell. 2.4V is way too low (unless there is some other parasitic voltage drop).
 

stopcrazypp

Well-Known Member
Dec 8, 2007
11,111
6,247
You might have killed your main power. Li-ion batteries are not made to sit uncharged for a year. I think the manual states somewhere that you should not leave it unplugged for extended periods.
Tesla had anti-bricking protection built in (and also a bottom buffer) since the early days when some Roadsters were bricked.
Plug It In

That said, if you decide to discharge the pack to absolute 0%, according to that blog, it can still auto-recover if plugged in within 30 days. But beyond that it's anyone's guess.
 

stopcrazypp

Well-Known Member
Dec 8, 2007
11,111
6,247
Lithium Ion batteries can sit for up to 5 years actually. They have very little self-discharge. The problem is that the car's computers always have some parasitic draw which runs the battery down.
I think that multi-year rating is for a fully charged battery cell. But it's different story if you discharge the cell to absolute 0% (2.5V).

Tesla's system in the Model 3 draws about 1 mile of range per day, so it's never going to be anywhere close to years of sitting (even if it started fully charged, which I suspect this pack did not).
 

disem

Member
Sep 28, 2021
11
0
Sarasota
Yes, the car connects to WiFi and still no connection to the app. If you see my first post, it won't even connect to a Tesla technician's computer. He suggested it may be because the main battery does not power up some modules. And again as in my initial post - can you charge the main battery directly at the terminals? I hear some people use their cars to power their homes, so there must be a way.
 

lolder

Member
Jun 11, 2016
946
851
SW Florida
300 volts is a low HVB, 230 is kaput. Only Tesla can service this even if they would but probably won't since it's salvage. A new HVB is probably the solution.
 

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