Tesla Motors Club

I’m having an issue with charging my MX at home, and hoping I can find someone who has had a similar experience and can suggest a solution. Thanks in advance for reading my novel!

Overview:
I have a late-2017 HW v2.5 MX 100D. When I originally purchased it, I had a NEMA 14-50 outlet installed in my garage on a 50-amp breaker on a 6/3 circuit and used the mobile connector for charging. For the first ~1.5 years I was able to charge at 40 amps with no problem, and then for an unknown reason (no electrical changes in the home) in August of this year (2019), I started to have the following issues:

• Charging often does not start.
• Receive error messages on driver display, “Unable to Charge, Disconnect Cable and Retry,” and “Charging Rate Reduced, Check Wiring.”
• When I can get it to start, it maxes out at 23 amps, and the “Unable to Charge” message remains for the entire charge. It does still show 245-252 volts, but that number only fluctuations by 1 or 2 volts when starting to charge and when charging.

Troubleshooting Steps Taken:

• Electrician checked NEMA 14-50 wiring and tightened connections as needed. No change.
• Tried reducing charging amps in MX. I have more success getting charging started if I set to 10 amps, but I still receive the error message. And when I start charging, it will only ever go up to 23 amps, even if I gradually increase it.
• Took MX and mobile connector to TSC. They advised no issues and were able to charge my MX on their NEMA 14-50 using my mobile connector, which I observed myself.
• Charged at destination chargers (Tesla wall connector) and Superchargers with no issues.
• Tried charging on a regular 110v/12amp connection on multiple outlets in my house, and was only able to charge at 8 amps, still receiving the “Unable to Charge” error message.
• Attempted standard-outlet charges at my neighbor’s house and had the same issues as I was seeing at my own house. This one is perplexing (more on this below).
• Ran a temporary, short (5-foot) circuit on a new 60-amp breaker, 4 AWG wire, and NEMA 14-50 outlet to test an entirely new connection. Same results.
• Purchased and installed a Tesla wall connector installed in my garage on a new 60-amp circuit. Thought maybe I could account for any issues on the current wiring and breaker, and that the wall connector might be able to handle any interference better. Same results as the mobile connector/NEMA 14-50 setup.
• Turned off all breakers in my house (including solar disconnect) with the exception of the wall connector circuit, thinking that something else may be introducing noise/interference that is affecting the unit. Same results.
• Had the power company come out and check the line at the street, and they even checked the power inside at my panel. They reported no voltage issues or interference.

Apparent Conclusions:

• Issue is not my MX or mobile connector (worked elsewhere, same issue on wall connector)
• Issue is not the circuitry (same issues on multiple circuits in my house)
• Issue is not interference from other devices in my house (isolated the circuit)
• Issue is not voltage/interference from the power lines (tested by power company)

Summary
I’m a bit frustrated right now because I have considerable time and money into trying to get this fixed and have tried to address all possible causes of the issue. I’m a bit perplexed that I have the same issue at my neighbor’s house, but the power company said there are no issues with the line (was thinking it’s the local transformer or something). I may try to explore this further. Perhaps there’s a tester that will detect relevant noise that the power company couldn’t detect? Is there a specific type of noise/interference for which I should be looking? Maybe it might be worth trying to install a line filter or whole-home surge protector to knock down the interference or voltage fluctuations.

I would appreciate any suggestions or other solutions anyone has found. Thanks!

Relevant Posts:

• https://forums.tesla.com/forum/forums/hpwc-won’t-charge-above-23-amps
• Suddenly can't charge above 24 amps?