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AC charging issue since 2020.44

SSonnentag

Rocket Scientist
Apr 11, 2017
1,717
2,177
Arizona
I'm not sure if this is actually related to the 2020.44 update I recently got or not, but for the past few days my S just cycles between starting to charge and charging, every 5 seconds or so. My HPWC clunks and then it disconnects and starts the cycle over again. Since we have two HPWCs, I swapped chargers and tried the other one, but get the same results.

The interesting thing is that as soon as I open the driver door, the charging starts up and keeps going until finished. But then the next time it tries to charge the cycle of clunks starts all over again while never actually letting the car charge. I let it sit for 2 days and it never was able to successfully charge until I opened the door again. I rebooted the car, which has had no effect.

Any ideas?
 

Electric700

Active Member
May 21, 2013
1,697
360
Florida, United States
Can you try restarting it? Try pressing the brake and two scroll wheels on the left and right side of the steering wheel, then wait 10 seconds. After the center screen restarts, do the same for the top two buttons. This should restart the driver's side screen.

If that doesn't help, you should report the issue using the Tesla app.
 

TMeister

Gearhead
Oct 6, 2016
271
365
Boise, ID
How about cleaning the signal pins (control and proximity) on either side of the ground pin on the car? I assume that you can see the IC light up as the scenario plays out? Does the car ever report an actual charge rate right after the HPWC relay engages? Still have a UMC? Same result?

The door could put the car into a different state or it could be the state change causing the success. Have you tried the combo of having the door already open when you connect? If that works then it would seem the car needs to be in a different on state that enables charging.

Last thing of course is to power down the car from the MCU, wait 2 minutes and power up. Or maybe that's the first thing.:)
 

joules17

New Member
Nov 16, 2020
1
0
Kitsap, Washington
I have had exactly the same charging issues that the OP precisely presents. This has occurred since 2020.44 update. Opening the door resolves the cycling of the charge process with the HPWC connected. There are loud "clunks" from both the HPWC and the car (I assume the sounds are from contactors) as the charging cycles. When it is cycling, the process never gets to the rate of charge - just "starting to charge" displayed on the IC. I have tried rebooting and power down to no avail. Are others experiencing this same behavior? And if so, have you found a resolution? I am hoping that the next update will resolve the issue. Model S100D March 2017 with with updated FSD computer and MCU 2.
 

Zuikkis

Member
Aug 19, 2020
224
256
Finland
I have the same issue, although I had it with 2020.40 already. Just got 2020.44 upgrade and it didn't change it.

I have OpenEVSE but I also tried with UMC and it does the same.

My car is 2013 but recently upgraded to MCU2. Others have retrofitted MCU2 as well?

Are you in cold region? My car doesn't seem to do it every time, only when it's cold. Below 0C (32F) or something.

If I set the charge amps to very low value, it's able to start charging. My guess is, when the battery is cold, charging amps are limited.. Perhaps there is some communication issue that the charger tries to charge with too much current, then some protection circuit kicks in and cuts everything..

I fear that this gets worse when winter really comes..
 

capcave

Member
Oct 29, 2020
8
0
London
This is exactly the issue I have both with a high powered (22kw) AC and the mains charger. Have tried dialling the high powered charger to the minimum (10A) and nothing - just clicking and then stops. Rebooted the car, rebooted the charger nothing seems to work. Both chargers work fine on my other other car (renault). I just booked a service with Tesla but they can't get out to me for a week. 2020 Long Range S.
 

capcave

Member
Oct 29, 2020
8
0
London
This is exactly the issue I have both with a high powered (22kw) AC and the mains charger. Have tried dialling the high powered charger to the minimum (10A) and nothing - just clicking and then stops. Rebooted the car, rebooted the charger nothing seems to work. Both chargers work fine on my other other car (renault). I just booked a service with Tesla but they can't get out to me for a week. 2020 Long Range S.
Some additional testing here : tried a spare high power charger and different lead, tried warming the battery up, put the mains power through a UPS for voltage stabilisation - none of it made a difference.
 

Zuikkis

Member
Aug 19, 2020
224
256
Finland
For me it seems to work now that I reduced charging current to 5A from Tesla menu. (5A three-phase, so about 3kW power.)

I would like to see this fixed, though! But I don't want to report to Tesla because closest SC is over 100km away and I don't want them to take away my car. :) And I'm out of warranty so I don't want them to start swapping components at my cost. This is obviously a software bug which can be fixed by OTA update, it's not a fault in car.
 
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George I

Member
Oct 24, 2017
45
34
Toronto
Same thing began early Nov. this year. I have a pre-refresh 2016 S 90D with original MCU1.
On 23Nov "I called"(you cannot call you have to use the app-not very convenient as I work all day with a laptop and do not use a cellphone at work, wife similar so we share one cellphone) Tesla service & have appt on Wed 2Nov. Hope there is a update very soon that solves this as I'd rather not have to drive to the service centre.
 

capcave

Member
Oct 29, 2020
8
0
London
Charged the car on a Supercharger and a few hours later plugged it in and now it all worked fine (although I am only getting 2 out of 3 phases working). Will re-test after it's had overnight to cool down in case it's the battery temperature allowing the AC charge to run.
 

ccharleb

Member
Dec 19, 2014
150
70
Montreal (QC), Canada
Hello,

Having this issue since October 31 (colder weather? I'm from Montréal/Canada). I don't think I have any issues if the battery is warm/hot.

2015 Model S 85D, MCU1, AP1
Car was on firmware 2020.36.11 when I noticed the problem. Now, problem is still there on firmware 2020.40.9.2.

Like others, while the charge is trying to start without success (contactors cycling on-off every 5 sec), opening a door will start the charging.
Also, from the app, if I turn Heat-On, charging will start properly.

If I take a look in the Notification Menu, I have a bunch of:

"Date" "Time" BMS_w31
Unable to start vehicle
Service is required

Tesla Mobile canceled my appointment by saying it's a known issue and should be solved in the next 1 or 2 releases.... I was on 2020.36.11 at that time...

Christian
 
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Zuikkis

Member
Aug 19, 2020
224
256
Finland
My guess is that the MCU must be awake when charge starts. Opening a door or using the app will wake it up.

This is only an issue if you use timed charging, I think..
 

George I

Member
Oct 24, 2017
45
34
Toronto
follow up to my post of 25Nov2020
Brought car to Tesla service today. Their logs show me charging on a "foreign" charger (ie generic J1772) which i have not used in a very long time. Charged there on their HPWC both immediately and with scheduled charging without probs. No $$, told to call Tesla HPWC service & given number. With their agreement I went home hit reset on my HPWC then threw circuit breaker to off for ~12min then turned on and set scheduled charged for 45min later. Charged normally. I stop charging as I'm on time of use electricity and have set to restart charging at 20:00 tonight. Will write again if any issues come up.
 

evfeh

Member
Nov 13, 2016
83
86
Illinois
I’ve seen this behavior happen recently. My battery is at 74% level, and I have it scheduled to charge at 1:15a to 75%. I’ve heard clunking one and off and showing “preparing to charge” and doesn’t charge. I’ll reset my HPWC as well and report back.
 

sorka

Well-Known Member
Feb 28, 2015
7,858
5,777
Merced, CA
Every time I have even the slightest inkling to upgrade to V10, I read something like this and tell myself "no way". Still really glad to be on V8.1:p
 
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evfeh

Member
Nov 13, 2016
83
86
Illinois
Noticed the same issue today. I also think it’s cold weather related and only when the car is asleep and cold for a few hours. Scheduled charging can’t start the charge. However, if I open the door and wake up the car, it will start charging normally.

I’m on 2020.48.5.
 

Zuikkis

Member
Aug 19, 2020
224
256
Finland
Recently I purchased "Scan my Tesla" app and the necessary Bluetooth OBD dongle.

There's a parameter "BMS max charge" which shows currently allowed maximum charge power. It goes very low when battery is cold, can only be a few kW.

You can see the same thing in the dashboard power meter, you get yellow dotted lines showing the current maximums.

It seems that for some reason charger doesn't respect this maximum setting, and tries to charge with too much power. Then BMS hits the panic button and cancels charging completely. But for some reason it happens again and again in 5sec intervals..

Correct behaviour would be to cancel the charge and perhaps start battery heater so charging is possible at a later time? Perhaps the heater actually IS started, but it's just the charge retry that happens too soon?

I have now charged at very low power (3kW), and it has worked so far. I use scheduled charging because electricity here is cheaper at night.
 

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