Confusing AC charging issue on late 2016 90D S

[ArgusIII]

Hello friends,

I recently created an account here after not being able to figure out the cause of my charging issue. I have been lurking this forum for some time and it has been of great help fixing other issues in the past so I just want to say thanks before going any further. It’s a long read so I hope you can hang in there.

Problem:
When charging at home my Dec 2016 tesla model S using my gen 1 mobile connector on a NEMA 14-50 outlet, the amps try to ramp up to my set point of 24 amps and when it reaches 10 or so amps, it drops down to zero. The car tries to ramp up the amps again and it continually fails. I can hear the mobile connector making a clicking noise. After 3-4 tries the car shows a red light on the charge port and the following errors:

CHG_u014 Charging equipment reports error
CHG_u007 Charging equipment reports error
CHG_f083 Cannot charge-poor grid power possible

Here is the strange part. I get the same errors and red light when I tried two different tesla destination chargers, a third party level 2 charger and a friends gen 2 mobile charger at his home NEMA 14-50 outlet. For these reasons I do not think the issue is my mobile charger or outlet. Supercharging works fine so I suspect its my on-board charger.

Fix attempts:

1. Two finger restart-no changes
2. Car off from central touchscreen-no changes
3. Wheel configuration restart-no changes
4. Retightening of ground on NEMA 14-50 outlet-no changes
5. Car off from central touchscreen+12V disconnect+HVIL disconnect + 5 minute wait-no changes

Found workarounds:

1. I can charge the car at 6 amp at 240V (About 1.4 kW). Any more than 6 amps and it eventually goes to a red light around the charge port.
2. I can charge the car at 6 amp at 240V (About 1.4 kW) and then increase to 15 amp after 3 hours. Any more than 15 amps and it eventually goes to a red light around the charge port. This works sparingly and less often after a few weeks with this issue. It also sometimes fails two or three hours after reaching 15 amps.
3. I have been able to get the full 24 amps back by leaving the car unplugged and idle over two days. I realized this after leaving my car unplugged during two different camping trips. I am not sure what the 2 days of idle time do to make the 24 amp charging work.

Additional info that may also connect to this issue:
I am the second owner and purchased the car in Nov. 2020. Soon after getting my NEMA outlet installed in Jan 2021 I was only getting 24 amps instead of the possible 32 from my installation. I know the car can pull 48 amp with the right outlet but my home circuit breaker box can only support 32 amps continuous. I took it to a third party shop to see if the issue was the common ruined on-board charger or ruined fuses found in this thread:

Replacing Onboard Charger Gen3 2017 MS75D...My Experience (With Photos). You can better see the internals of the EU version in this video :

Found out there was a portion of the on-board charger that showed a circuit board burn. Third party tech (used to work at Tesla btw) and I thought it would be best to just close it up and let me continue charging along at 24 amps. I get the CHG_f018 Unable to charge error every time I charge since the past two years but it used to always reach 24 amps.

The issues appeared after I had my front central intake duct assembly replaced (ASY FR END DUCTING WITH HORNS, MS2 1058073-00-B) recently by Tesla due to the loud fan issue talked about here:
Extremely loud noise when charging from the wall connector
Has anyone repaired cooling louvers?
Tesla also recommend that I change my charge port and on-board charger to address the CHG_f018 unable to charge error but I just told them to do the charge port only and leave the onboard charger. I didn’t want to pay $3000 CAD to go from 24 amps to 32 amps. I was expecting to receive my car back with it able to charge at 24 amps but was only limited to 6 amp after visiting them.

If my on-board charger is dead, how can I still charge at 6 amps? Why can I sometimes get 24 amps after leaving it idle? Thanks for listening!

TLDR: Half broken on-board charger was able to charge at 24 amps for 2 years and now can only do 6 amps. Strange workarounds can sometimes allow more amps.

 

[ArgusIII]

Also tried removing and reinserting thermal controller fuse as well as charger fuse. Still same results.

Any help would be appreciated.

 

[BertJ]

Also tried removing and reinserting thermal controller fuse as well as charger fuse. Still same results.

Any help would be appreciated.

Not sure what your question is here. Sounds like you’ve correctly identified the problem and your third party shop was not able to fix it. The obvious solution is to pay the 3k CAD and replace the charger. I doubt there is anyone on this forum who can cheaply tell you how to fix a burnt circuit board, especially if we don’t know if the burnt board is the cause or the symptom. Perhaps you could replace the charger cheaper from a wrecked car but there is the obvious risk that we are guessing at the totality of the diagnosis. At least with a Tesla fix you get a warranty for the repair. My Tesla is the same year as yours, so far I’ve not had any major problems such as this but it is the gamble we take with cars as their warranties expire. Hope it works out for you!

 

[ArgusIII]

Thanks for the input BertJ.

Just wanted to see if others ever had the same issue. I have read on other posts of on-board chargers going from either 48A down to 24A or down to 0A. Those cases makes sense to me but I haven't seen a case like mine where they throw errors but can still get some charging. 6A in my case.

Not particularly looking for board repair, but curious why I don't get the 24A charging I used to get before Tesla replaced my front central intake duct assembly.

 

[KalJoMoS]

Sorry, can’t help you in the situation you are but as you have been deeply in-and-out of the car and presumably also around the charger, have you checked their ground straps? Presumably your car has the Gen2 single charger so Tesla has dedicated high voltage system Service Bulletin (SB-13-44-010) to upgrade from single charger to dual and there is specific section (revision3) about the chargers ground straps. Sorry haven’t seen it myself but have read it from list of bulletins.
And there is another high voltage system Service Bulletin (SB-15-44-006) about an installation of relay box to enable 32A single phase charging if customer complains of charging rate limited to 16A on single phase charging equipment that can provide more than 16A.

 

[dbldwn02]

Mine had some similar issues going on. I replaced the charger myself for $350 (used off EBay). It took the whole day, not knowing what I was doing.

Here's my write up, if you feel so bold to try it yourself...lol

Replacing Onboard Charger Gen3 2017 MS75D...My Experience (With Photos)

Here is my experience replacing my onboard charger on my 2017 Tesla MS75D. Disclosure… Don’t try this at home, YMMV, High voltage, you can kill yourself if you do something stupid, yadda-yadda, I’m not liable if you do this, warranty void, blah blah blah… My car specs: 2017 MS 75D (USA) Gen...

teslamotorsclub.com

 

[ArgusIII]

Sorry, can’t help you in the situation you are but as you have been deeply in-and-out of the car and presumably also around the charger, have you checked their ground straps? Presumably your car has the Gen2 single charger so Tesla has dedicated high voltage system Service Bulletin (SB-13-44-010) to upgrade from single charger to dual and there is specific section (revision3) about the chargers ground straps. Sorry haven’t seen it myself but have read it from list of bulletins.
And there is another high voltage system Service Bulletin (SB-15-44-006) about an installation of relay box to enable 32A single phase charging if customer complains of charging rate limited to 16A on single phase charging equipment that can provide more than 16A.

I didn't know about this bulletin. I checked the Vin dates and i think my car is just outside this range.

 

[ArgusIII]

Mine had some similar issues going on. I replaced the charger myself for $350 (used off EBay). It took the whole day, not knowing what I was doing.

Here's my write up, if you feel so bold to try it yourself...lol

Replacing Onboard Charger Gen3 2017 MS75D...My Experience (With Photos)

Here is my experience replacing my onboard charger on my 2017 Tesla MS75D. Disclosure… Don’t try this at home, YMMV, High voltage, you can kill yourself if you do something stupid, yadda-yadda, I’m not liable if you do this, warranty void, blah blah blah… My car specs: 2017 MS 75D (USA) Gen...

teslamotorsclub.com

I closely read your thread. Thanks for carefully documenting the repair. I'm leaning more and more to just doing the swap myself.

My slow charging has been getting me by for this past month or so but as the temperatures cool my home charging sessions are getting longer and it is getting more and more irritating living with a limping charger.

 

[dbldwn02]

I closely read your thread. Thanks for carefully documenting the repair. I'm leaning more and more to just doing the swap myself.

My slow charging has been getting me by for this past month or so but as the temperatures cool my home charging sessions are getting longer and it is getting more and more irritating living with a limping charger.

It's not terrible to do it on your own. Just takes 3-6 hours depending on your skills and if you have everything prepped.

Your issue is starting to sound like a heat issue. Are you sure your charger coolant pump is working? You should be able to see this in the service menu. You should also be able to hear it when you disconnect the 12 volt battery and reconnect.

 

[ArgusIII]

It's not terrible to do it on your own. Just takes 3-6 hours depending on your skills and if you have everything prepped.

Your issue is starting to sound like a heat issue. Are you sure your charger coolant pump is working? You should be able to see this in the service menu. You should also be able to hear it when you disconnect the 12 volt battery and reconnect.

Hi dbldwn02,

Thanks for the advice. I did check the charger coolant pump and would hear it when disconnecting the battery and reconnecting. I ended up getting the on-board charger replaced with Tesla. They charged 3700 CAD (ouch!) and provide a 1 year/20000 km warranty.

I looked at the used ones on ebay and couldn't find anything under 1000 USD. I would then have to worry about import fees. If I was going to sell the car in 1-2 years I would have likely done the swap myself but i hope to keep my S for a while so i decided for a new charger.

It charges up nice quick now. Very convenient for the colder days we now have.

 

[dbldwn02]

Hi dbldwn02,

Thanks for the advice. I did check the charger coolant pump and would hear it when disconnecting the battery and reconnecting. I ended up getting the on-board charger replaced with Tesla. They charged 3700 CAD (ouch!) and provide a 1 year/20000 km warranty.

I looked at the used ones on ebay and couldn't find anything under 1000 USD. I would then have to worry about import fees. If I was going to sell the car in 1-2 years I would have likely done the swap myself but i hope to keep my S for a while so i decided for a new charger.

It charges up nice quick now. Very convenient for the colder days we now have.

Dang...that got more expensive in the past year. Wish they would give some more credit for the bad one.