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Need Help! Charging Issues, Errors, Max 23 Amps

kcdk99

Member
Dec 22, 2017
19
0
New York, NY
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:
 

ajdelange

Active Member
Dec 10, 2018
1,077
638
Virginia/Quebec
I'd say the next step is to monitor the line voltage over time. This will require investment in or rental feels for line voltage recording equipment but that's about all I can think of. Line voltage may have been within spec when the power company checked it but what is, perhaps, going on the rest of the time. I'd say you've done a pretty thorough job here. That's all I can think of at the moment.
 

alstoralset

Man from another place
Nov 23, 2018
125
302
Pacific Northwest
You might want to try charging another Tesla at your location, in the unlikely event the issue is due to a problem with your Tesla that somehow only manifests when the car is in your neighborhood.

And/or, maybe try temporarily resetting your "Home" location, in case it's an issue with a setting that triggers only when the car thinks its at home.

Hmm, I see it happens at your neighbor's house also. Unless it's your next door neighbor, that probably rules out the 'home' thing.
 
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kcdk99

Member
Dec 22, 2017
19
0
New York, NY
I'd say the next step is to monitor the line voltage over time.

Thanks, good suggestion. I'm just concerned that even if I do find fluctuations, the power company might be resistant to acknowledging. Hopefully they will if I can show them the data. Don't whole-home surge protectors help with fluctuations, or will I need something like a voltage regulator or filter? I can't seem to find the exact info online. Will keep looking.
 

Hebert

MXLR, RN1153, 7/20, Blue/Black/5/20", EDD Jan
Apr 28, 2019
149
136
Peoria, AZ
Do you or your neighboor have an electric dryer? If so, have you noticed if they don't get as hot as normal?

Did the power company measure the voltages of both l1 and l2 at your meter?
 

Tessaract

Member
Aug 12, 2019
337
338
Ottawa
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!

Wow. That's a pretty thorough debugging list. I also would concur with the suggestion to monitor both L1 and L2 voltages, in case the power system has developed a high-resistance neutral connection somewhere (which could lead to fluctuating and unequal L1,L2). However, since Teslas don't connect to neutral when using a 240V connection, it's hard to imagine how an unbalanced line voltage would affect the Tesla, as long as the L-L voltage was still constant.

The other thought I had was a recently-developed grounding problem. Since Teslas only connect to L1, L2 and G, and the HPWC and UMC both contain GFCI circuitry, something "wonky" could be happening there.
 
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Hebert

MXLR, RN1153, 7/20, Blue/Black/5/20", EDD Jan
Apr 28, 2019
149
136
Peoria, AZ
A ground problem, interesting. That's a good idea. How would you test it? Maybe temporarily disconnect the ground to the HPWC?

It could be something in the car still like an intermittent onboard charger error. If you could find another owners HPWC and see if you get more than 24 amps. If that works, then you are back to something upstream of your breaker.
 

mswlogo

Well-Known Member
Aug 27, 2018
6,150
5,310
MA, NH
Great debugging. Really stumped.

Just a couple thoughts 245-252 Volts, that’s unusually high.

What does 120V read?

My only thought is you have some ugly noise on the lines. Neighbor too.

They make many types of AC filters for audio equipment usually. Some is overpriced snake oil, some is real, like DC offset problems. Which have cheap fixes.

I would try one of these filters. Especially ones that do DC offset filtering. Just try a 15A unit. You might find one at Best Buy or Amazon. They also make pure sine wave regeneration units.

This is just for a test. You can return the unit after.

Like someone said neighbor might have the same issue.

Try 120V on someone you know at least a mile away. You sort of already did that at TSC. But try 120V at another residential location.

Very curious issue. Still would not rule out the car. Maybe it’s normal noise filtering is malfunctioning.
 
Last edited:

Tessaract

Member
Aug 12, 2019
337
338
Ottawa
A ground problem, interesting. That's a good idea. How would you test it? Maybe temporarily disconnect the ground to the HPWC?

It could be something in the car still like an intermittent onboard charger error. If you could find another owners HPWC and see if you get more than 24 amps. If that works, then you are back to something upstream of your breaker.
I'm not completely sure how to test a grounding problem. I'm concerned that disconnecting the ground from the HPWC would cause it to completely shut down charging, although that in itself might be a strong hint... May be worth trying.

At this point, I haven't yet developed a fully thought out description of what "wonky" is. I guess I was thinking along the lines of a neutral being open somewhere, and the unbalanced currents flowing through the ground connection (by means of the bonding strap in the main service panel). Or perhaps the bonding strap in the service panel having become corroded and high resistance, thereby changing the house neutral potential to something other than ground potential. One interesting way to test this might be to monitor L1-ground and L2-ground voltages, in addition (or subsequent to) monitoring L1-N and L2-N voltages. And perhaps also monitoring N-ground voltage (should be near zero all the time). It should go without saying that all these voltages need to be monitored on the Tesla charging circuit, rather than some other arbitrary circuit or location.

Oh, and I also agree that trying to charge a different Tesla at the problem location would be an interesting experiment.
 
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mswlogo

Well-Known Member
Aug 27, 2018
6,150
5,310
MA, NH
I’m pretty sure it will shut down with no ground as it will check each hot to ground and if it’s not happy it will error out.

Based on the tests you did, I’m not sure lifting a ground will get you anywhere. Especially where you did the 5 foot temp 14-50 run. Your ground is essentially Neutral.

You could have a ground issue but lifting it isn’t gonna get you any answers. Because I don’t think it will run.
 

posity

Member
Jun 30, 2018
185
348
Southern Oregon
Great job of attempting to deduce the problem.

I work on power systems on ships which can occasionally have symptoms that are difficult to understand. The easiest thing to do at this point would be to put an oscilloscope on your L1/L2/Gnd connections while charging. With the right probe(s) and oscilloscope, you can zero in on any anomalies. The oscilloscope will allow you to definitively SEE what it is bothering the wall connector and mobile connector - instead of guessing based on the symptoms.
 
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mxnym

Active Member
Mar 9, 2018
1,056
417
Bloomington, IN
Great debugging. Really stumped.

Just a couple thoughts 245-252 Volts, that’s unusually high.
I didn't even think about this until I read the post I'm replying to, but it seems feasible that a higher than usual voltage could trigger the behavior and begs two questions that might merit further investigation:
1) Was the voltage this high when it was working?
2) Did it stop working after an update to the vehicle?

If 1 = No or 2= Yes, then this could very well be a software bug (where unable to charge is the incorrect message and the amperage limit may or may not be correct for the given voltage).
 

trekkie

Supporting Member
Supporting Member
Oct 2, 2019
104
55
Wake Forest, NC
the only thing I can think of was mentioned above, try another vehicle and see. I'm thinking its something funky on the input if your neighbor is having similar issues. Was there any recent lightning strikes nearby? I had a friend have a lightning strike and it ended up being (of all things) a fan in a bathroom melted and was shorting the other phase over and it was thermal related so after a while it'd heat enough to short them together and screw things up but then be fine when the electrician came out.
 

ajdelange

Active Member
Dec 10, 2018
1,077
638
Virginia/Quebec
Thanks, good suggestion. I'm just concerned that even if I do find fluctuations, the power company might be resistant to acknowledging. Hopefully they will if I can show them the data.
If you do find widely varying voltage at least you will have an idea as to what the cause of the limited charging is. The fact that you seem to be able to charge anywhere but at home or your neighbors is pretty strong evidence to my way of thinking that there is a problem with your utility feed. To give you an idea of what you might expect to see here's a recording over a week. I'll bet you can figure out where I charged at 72 A.

Graph21.jpg


Note that initiating a charge only dropped the voltage 4 volts. That's almost 3 standard deviations but clearly the voltage fluctuates over a week by at least that much.

You may have noticed that when you initiate a charge the current draw starts low and then rises gradually. During that ramp the car is calculating the voltage drop per ampere change in current. That number is the resistance between the source and the car charger. If it is too high the car concludes that you have not properly inserted the plug or have loose or corroded wiring, reduces the current and fires off the warning message. This is what the car thinks is happening in your case. The question is why.

If the the service entrance wires to your house are loose or corroded (they are usually aluminum) or if a breaker in your house is not contacting the panel stab well enough or a screw is loose at the breaker or charging outlet then you will see an excessive voltage drop as charge current ramps up. If, OTOH, a connection between the pole transformer and the feeder to your house or to the high voltage line is not robust you would get the same effect - even if your neighbor turns on his A/C. IR pictures of the pole splices are a great way to detect such things and IR pictures of your panel (with the cover off) can be revelatory too.


Don't whole-home surge protectors help with fluctuations, or will I need something like a voltage regulator or filter?
Surge protectors are for surges (i.e. lightening strike voltage spikes) and will not cover fluctuations of the kind described above. You should not need a voltage regulator. What the utility gives you should be good enough to satisfy your Tesla.
 
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kcdk99

Member
Dec 22, 2017
19
0
New York, NY
Did the power company measure the voltages of both l1 and l2 at your meter?

Haven’t noticed any dryer issues. Not sure if the power company measured both lines, but I’m getting your point. The breakers I’ve tried have all been on the right bus bar, so maybe I’ll try the left in case the right line has the issue and wasn’t tested.
 

kcdk99

Member
Dec 22, 2017
19
0
New York, NY
If you do find widely varying voltage at least you will have an idea as to what the cause of the limited charging is.

Makes sense. I’ll need to try the oscilloscope. And great info... Thanks

IR pictures of the pole splices are a great way to detect such things and IR pictures of your panel (with the cover off) can be revelatory

I’ll have to see if I can get my hands on an IR camera... or maybe it's a good excuse to buy one.

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?
 

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