Battery health test

[bluetrep1]

Menu => software => touch and hold your car model (like "model Y ") => release after 3 second => in the pop up box, enter "service" without quotes => press enter

Anyone tried? How long does the test take actually?

 

[Prodock]

I did not know this existed. I’m interested if anyone has done this as well.

 

[OrderAnxiety]

But why?

 

[pepperoni]

But why?

Buying a used Tesla? That’s why.

 

[Bikeman]

So, what if, when running this 24-hour test, you need to drive the car? Can one cancel the test while it is running without damage?

 

[Pianewman]

I just completed this battery health test. Completed in about 20 hours, in my garage, ambient temp around 55f.

Battery health: 89%, and at 100% charge, upper left "gauge" shows 294 miles.

Tessie app says : Battery health: 93.5%, degradation 6.5%

I'm wondering if the Tesla "battery health test" states the entire battery capacity, and Tessie is stating the usable capacity?

 

[pepperoni]

I just completed this battery health test. Completed in about 20 hours, in my garage, ambient temp around 55f.

Battery health: 89%, and at 100% charge, upper left "gauge" shows 294 miles.

Tessie app says : Battery health: 93.5%, degradation 6.5%

I'm wondering if the Tesla "battery health test" states the entire battery capacity, and Tessie is stating the usable capacity?

I’m curious, how many miles, and months of ownership? I wonder if the Tessie estimate will change too, now that you’ve completed a full battery health test.

 

[Pianewman]

Stupid. I thought I posted mileage, which is important.

Delivered: 12/27/2020, currently 36,000 miles. Lifetime Wh/mi: 289. 12k miles were steady state highway road tripping.

 

[JonB65]

Stupid. I thought I posted mileage, which is important.

Delivered: 12/27/2020, currently 36,000 miles. Lifetime Wh/mi: 289. 12k miles were steady state highway road tripping.

@Pianewman When you finished the test was the battery SOC on 100%? I ask because I'm trying to plan when doing this test and want to be able to drive to get it back to 90% if needed. Thanks.

 

[Pianewman]

JonB65: Yes. The test fully depletes the battery, sits at 0% for "x" amount of time, then charges to 100% and sits again for "x" amount of time. This allows the BMS to equalized cells, IIRC. The test says this may take up to 24 hours. Mine took about 18 hours, but I started the test with the battery extremely low, maybe 6%.

There's a lot of paranoia about letting the car rest at 100%. Personally, I don't believe the car will be irreversibly damaged by occasionally leaving it at 100%, it's just something you shouldn't do on a regular basis.

YMMV

 

[JonB65]

Thank you. I appreciate your detailed response. Quite helpful and just what I was looking for.

 

[JonB65]

Running the battery health test now. I drove the car down to 9% SoC.

After starting the test the car turned on everything it could and took the SoC down to 7%. Currently setting at 7%.

I'll update as this progresses.

 

[JonB65]

Update:

Battery SoC went down to 6% then started charging back up at 5:30pm EST.

If this does not pause along the way, I estimate it will finish around 11:30pm.

 

[JonB65]

Up to 35%. I realized I have my charge limit set to 50%. Hopefully the battery health test will bypass that setting.

 

[JonB65]

Been setting at 49% for the past 70 minutes. Not sure if this is a pause during the test, or if I've messed up by not setting charge level to 100% before starting the test.

 

[jjrandorin]

Everyone reading along is aware that this is in the tesla SERVICE menu, which is (technically) ment to be accessed by service personnel right?

I mean, people can do what they want with their cars, and I am not a tesla insider, but I do work in IT. There is a less than zero percent chance that every access of that menu isnt logged somewhere.

I doubt running the test in this thread does anything, but people should be aware that they are likely logging that they are accessing menus ment for tesla service. If you make a mistake in there and do something that damages something, there will be no hiding it from anyone.

 

[rjpjnk]

Been setting at 49% for the past 70 minutes. Not sure if this is a pause during the test, or if I've messed up by not setting charge level to 100% before starting the test.

My guess is it's due to the 50% limit. Keep us posted.

 

[Pianewman]

IIRC, the test respects the limit you've set.

 

[GtiMart]

I believe this service menu is a subset of what the service personnel have access to. I think it's meant for users to be able to perform some services to their cars themselves. I agree that it's most probably logged somewhere though
With that said, there's nothing special about that test. From what I understand, this test does a couple of things:
- empties the battery by spending energy without driving the car: run stator heating (as when heating the battery) and use the AC to fight that heat so we don't actually heat the battery. Fans will be running like crazy.
- charges the battery full and "counts" the electricity that goes in.
- Compares kWh in with supposed battery capacity to output degradation percentage.

I think you can achieve the same thing by applying the tips mentioned in the thread about "bringing back somme capacity". Run the car low, let it sleep at low SOC, charge full once in a while and let it sleep there. The BMS will most probably give you the same result without putting wear on your stators and AC.

 

[JonB65]

Test complete:

Battery Health: 90%
Miles on car: 24,028 miles
Purchased: March 2021
MY AWD

Car did charge to 100%, finishing up at 3:30am.

I hope this has been helpful.