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Need Help! Charging Issues, Errors, Max 23 Amps


Well-Known Member
Oct 9, 2013
Thanks. Forgot to mention that I did have a loaner MX with its own mobile connector while they were troubleshooting mine. Same issue with the loaner MX / mobile connector.

That's telling, I think. Combined with your car charging fine at the Service center, it clearly says there's something about your connection that Tesla's programming doesn't like - something that apparently changed a few months ago.

I don't have any bright ideas what that might be, unless it's line noise like folks have been speculating above. See if you can get a power conditioner for a decent price or as a loaner to try out, maybe?
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Supporting Member
Nov 13, 2017
Edwardsburg, MI
Hi kcdk99,

You definitely have a wonky problem...

I agree with the IR check. We had great success with that technology preempting problems at work.

I would add a couple more points to check.
The incoming wires into the top of your breaker panel.
I had an instance of circuit breakers tripping and all of the connections were "tight."
The problem was a major breaker had the lug screw cross threaded.
It could not be tightened more but had a poor high resistance connection...
The breaker was replaced and the problem was gone...
It could also be the MAIN breaker in your panel...

Connecting to the left or right bus in the panel will not change anything
as a 240 volt circuit uses both sides of your panel's bus.

Another area I experienced a wonky problem was with a bad meter base.
The power company had to remove the meter to check the connection...
One of the lugs had been broken and visible arcing damage could be seen.
Be sure the lugs that receive the meter are clean and tight... AND properly sized.

A contrarian point of view...
If you are expecting 240 volt power and are receiving 250 volts that is fine...
If you are on the weird semi commercial 208 volt system masquerading as a 240 volt system
you will have nothing but trouble...
Low voltage will cause the Amps to rise for the same load.
High voltage will cause the Amps to fall for the same load.
Your lower Amp successes would seem to point to a low voltage problem.

Good luck - You need it and some capable electric helpers.



Active Member
Dec 10, 2018
I see that you’re making out around 147 volts. Is the fact that my car is showing me hitting 152 a concern or potentially the issue as suggested above?

Nominal is 240 V. I did note that you have seen 252 V in your investigations which is 5% high. That should be OK if it is stable. If, however, 252 drops to 240 when a 23 amp load is imposed that suggests an impedance of about 0.5 Ω which is high and might be responsible.


Active Member
Dec 10, 2018
If you are on the weird semi commercial 208 volt system masquerading as a 240 volt system
you will have nothing but trouble...
Shouldn't be any problem with this. The manual's only caveats WRT 3 phase connections is that earth must be provided and that the stinger not be used in a center tap grounded delta configuration. As he is seeing 250V he clearly is not connected to a stinger.


Dec 22, 2017
New York, NY
1) Was the voltage this high when it was working?
2) Did it stop working after an update to the vehicle?

Wow, thanks... this could be my answer.

According to my TeslaFi data (which isn’t the same as data from a tester, of course):
1) Yes, I’m showing max voltages of around 249 both before after the issue started. This probably doesn’t account for voltages as the charging is trying to start, and can’t remember it being lower beforehand.
2) Not sure why I didn’t look at this before, but this is intriguing:
  • Issue first starts 3-May-2019, the day after update to 2019.12.1.1 4b1dd29
  • Issue goes away on 28-June-2019, when I update to 2019.20.4.2 66625e9
  • Issue reappears after I update to 2019.24.4 73fb1ab on 27-July-2019
So, it seems to be linked to versions of the software. Maybe there is some interference in the line, but certain versions are more sensitive to it than others. I need to pass this information on to Tesla.

Here’s the timeline of my charging from March-Today, showing when I was maxing out at 23 amps, and able to get a full 40 amps:


MXLR, Order 7/20, 5 seats/Blue/Black/20", EDD Jan
Apr 28, 2019
Peoria, AZ
Since this problem happens with the loaner X and the mobile charger that came with it, I think that means the problem is upstream of your breaker. I have always found the hardest problems to troubleshoot end up being power company problems.

At this point, I would suggest ask the power company to come out and help again. If you recreate the problem when they are there, they have the tools to watch their side. Maybe even show them it happening at your neighbors. Those guys are always fun to be around and would love to checkout your X.


Maker of Lightning
Sep 25, 2019
Penngrove California
The 23 Amps is an interesting number. Sounds like your Tesla and/or Connector think it is a 30 Amp circuit. If you can rent, borrow or have your power company use a Dranetz monitor on your feed, it will tell the tale, be it voltage issues, arcing, high harmonic content or most other power impairments.


Mar 1, 2015
Oak Hill, VA
I read somewhere that there are two settings on the HPWC - one for 245v and below and another for 245+ volts. Not sure if mobile charger has a similar setting, but it may be worth looking into this.


Supporting Member
Nov 13, 2017
Edwardsburg, MI
Hi Rananth,

Good catch! On the HPWC Gen 2 there are indeed a second set of dip switches that need to be set differently
for line to neutral voltages above 240 volts.
This is shown on page 20 (English version) of the Wall Connector 80A Single Phase Installation Manual.
Tesla part number 1069742-00-C.

This extra set of dip switches are NOT present in a Gen 1 HPWC.
The installation Manual for Gen 1 HPWC is Tesla part number 1042840-00-A Rev 2

There are no dip switches present in any of the UMC or Universal Mobile Connectors.


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