Charging Issue: HPWC or On-board Charger

[BrianD]

I am having a intermittent issue charging using my HPWC. I usually have it setup for scheduled charge at 3am. Occasionally, when I went out in the morning and the vehicle was non-responsive. After trying to turn it on I will eventually get some message like “unable to charge”, “car needs service”, etc. It did not charge overnight as scheduled but was perfectly drivable after it eventually woke all the way up and errors cleared.

After a ~6 months of this happening maybe 2-4 times/month (very intermittent) I took it in and they replaced the on-board charger. I brought it home and it actually failed the scheduled charge that 1st night so brought it right back. This time they replaced the coolant heater. It seemed to be doing better but I have had a few failures recently so got it back in as warranty is nearing expiration and they diagnosed/replaced on-board charger again. I challenged them whether it was really a bad on-board charger again just a couple months after replacement but they felt confident in their diagnostics.

A few interesting things to note:
- I’ve never been able to reproduce any charging errors when doing it on-demand (not scheduled); works fine every time including right after one of these failures
- My last loaner (much older Model S) had the same issue two nights. Even with this information they still said my on-board charger was bad and did not attribute it to HPWC; although they did not completely rule it out. They said they would diagnose loaner but of course I never heard back.
- No issues supercharging

I’m not sure what to make of all this. I’m concerned the HPWC could be damaging the on-board charger somehow but have no idea how to have it checked. I have not used my HPWC since the last on-board charger replacement - relying on mobile charger & occasional supercharge but that isn’t sustainable. With my warranty expiring in about a month I would really like to get this resolved once and for all. Any insight or suggest would be very much appreciated.

 

[BrianD]

Here is a picture of the HPWC. Nothing stands out to me visually.

 

[Hebert]

I agree this problem happening on 2 different cars points to the HPWC area. A couple of questions.

Do any codes appear on the charger leds when this occurs?

Does this happen only when using Scheduled Departure or using a specific time to start charging?

Do you use the same departure mode with the mobile connector? How many amps in this case?

Do you have a friendly neighbor with an HPWC to try for a few days.

Did you ask the SC to swap out your HPWC? (I'm not sure they do this....)

 

[BrianD]

Do any codes appear on the charger leds when this occurs?

I did not look at those leds unfortunately. Only one time I recall, and I believe it was the loaner, things were so 'dead' that I had to turn off the breaker to the charger to get it out. That was not normal even when the overnight charging failed though.

Does this happen only when using Scheduled Departure or using a specific time to start charging?

I have only seen it happen when I have a set time to charge 3:00am - this is what I use 90% of the time. I have only used scheduled departure a few times, and I have not see it fail when set to just start charging as soon as I plug in, but that is also something I do less frequently. I use an electricity provider (Griddy) that bills based on market rates so overnight charging is the cheapest.

Do you use the same departure mode with the mobile connector? How many amps in this case?

I did test the same scheduled time charging 3:00am using my mobile connector and have not seen that one fail yet but it has not been a long period of time. Unfortunately when using the mobile connector on a regular wall outlet is so slow I pretty much have to leave it always charging and can't do the scheduled.

On the HPWC, I was originally using 72 amps but after the first on-board charger replacement I dialed it down to 48. It was set to 48 for the second failure and the loaner model S that failed a scheduled charge as well. My thought with reducing it to 48 is that is what I would get if I replaced it with latest gen 3 so wanted to see how it worked for me.

Do you have a friendly neighbor with an HPWC to try for a few days.

Not that I know of unfortunately. I'm sure I could find one to test on but that is part of the biggest problem - it does not happen consistently enough. Previously it could go a week or two without failing then all of the sudden fail a couple days in a row.

Did you ask the SC to swap out your HPWC? (I'm not sure they do this....)

I did. The SC said they would send out a mobile tech to check it out. Then someone else called to tell me their mobile techs do not work on wall chargers and cancelled my appointment. They suggested I schedule with the home energy group. I've sent a couple emails trying to get something figured out but I'm not too hopeful. I believe the warranty on this is only 12-months.

I am still waiting on a callback from SC to tell me what they found with the loaner vehicle. It is so difficult to reach someone at SCs these days who knows if I will ever get an answer.

I have not tried my HPWC yet since the last on-board charger replacement. My main fear is it could be damaging the on-board charger. Maybe I should just start using it again though, if it is going to cause a failure, it is better it happens in the next few weeks before my vehicle warranty expires

 

[BrianD]

I thought I had heard, and possibly read on the forums, that the 2nd gen Wall Charger only had a 12-month warranty. However, I just stumbled across this page on Tesla's site which shows "48 month warranty".
Second Generation Wall Connector

Can anyone clarify for me?

 

[Hebert]

Interesting. That leads me to suspect either some sort of HPWC miswire (ground?) or a software bug or maybe HPWC is starting to fail.

Coming up with a way to swap out those possibilities might lead to a solution.

 

[rallykeeper]

I've had exactly this problem on my Model S and Model X (both 1H 2017 and MCU 1). It's been pretty rare on our Model X, but pretty frequent on our Model S.

We have HPWC gen 2 (I think -- we purchased in early 2016). We are only set up to charge at 40 amps.

I've also received all the same advice (and part of the onboard charger was actually replaced on my Model X, and they found a bad fuse for the coolant pump in my Model S).

I've done a lot of testing and have concluded that it is entirely related to scheduled charging. It never happens when I start charging right away.

Moreover, I've also established that it matters what time you plug in the car relative to the scheduled charge. If scheduled charge set within 0-2 hours, then it almost never happens. If it's set to 2+ hours away, it's possible that, but not guaranteed, that it will happen. At this point, I get the issue about 1 out of 2 attempts on the Model S (it's like 1 out of 10 times on the Model X).

When it fails to charge, the next morning the MCU goes through a series of errors, crashes, and then requires a manual reset. After that, no issues.

Obviously the coolant pump fuse was a problem, however, I've come around to the conclusion that this is either software or a failing MCU. There's a distant possibility it has something to do with my 12v battery (I've historically had really weird issues with both cars' 12v).

I'm strongly inclined to believe that it's a failing MCU. My Model S has other telltale signs of a failing MCU or maybe just failing eMMC (weird sleep issues, bluetooth problems, map problems, long reboots, long wake up from sleep, etc). Our Model X has some failing MCU signs, but nowhere close to as many as the Model S and while it has more miles, it's about 5 months younger than the Model S.

My suspicion is that the MCU somehow goes into too deep a sleep and can't wake up properly for its scheduled charge or only wakes up part way.

I've been around the block for the past 12 or so months with service on this -- they can't replicate it. I gave up in February when the infotainment upgrade was announced and decided to just get a new MCU for the Model S.

I finally have an appointment scheduled and will report back to see if that fixes it. Crossing my fingers....

 

[gavine]

My suspicion is that the MCU somehow goes into too deep a sleep and can't wake up properly for its scheduled charge or only wakes up part way.

This is what I was thinking. Isn't there a setting where the car doesn't sleep? I forget what it's call or under which menu you can find it but worth a try. If no setting, how about putting it in camping mode overnight?

 

[BrianD]

Very helpful - and nice to know I'm not the only one dealing with some sporadic!

I've been thinking along similar lines of it has something to do with sleep as I have never seen a single failure when set to charge right away.

I had not considered the MCU. I struggle to reconcile that it both my X and the loaner S would have a failing MCU but it is possible. I'm going to see if they can inspect and/or replace the HPWC to rule that out....so far just sending me running in circles though.

 

[rallykeeper]

Update.

Tesla ended up replacing the charger itself on the Model S. They found faults that apparently indicated problems there.

However, the infotainment upgrade was unavailable when I got to my appointment and the SC was unable to find anything wrong with my current MCU 1.

Needless to say....I got the same series of errors 5 days after getting the car back. I did manage to successfully charge the car via scheduled charging one time (with a 3+ hour advance). Since then, it has failed every time other than the scheduled charge which was only set for 5 minutes later.

The new quirk is that the second time it failed, it didn't go through a complete reboot process. The error messages just sort of reconciled themselves.

I remain convinced that it's a bad MCU or software bug that is somehow related to the car going to sleep. Btw, we have a new Model X and it's scheduled charging just fine... (As did my MCU 2 loaner that I had while my car was in for service).

"Mobile" appointment currently scheduled. It will obviously be shifted to a SC visit and I'll update again.