At Home 240V charging Interrupts all the time

[BLH17]

I have both a Wall Connector and Mobile Connector in my garage (14-50 Hubbell receptacle). I used to charge at 32 amps overnight no problem, almost 1.5 years later it started disconnecting so I decide to drop amps to 24, that worked fine for a bit but it slowly got worse, more interrupts - this was on my Wall Connector. It started getting so bad I tried the Mobile Connector instead and it worked better but quickly had the same issues. They cut down to 16 amps max, interrupt all the time without much help but saying a/c issue. 2 service center stops have resulted in nothing found out but blaming my house electrical (it charged fine on their Wall Connector). The first interrupt usually happens within 20 minutes. Waiting 25min+ and opening my app forces the charging to restart, but there is zero reason to need to baby this.

The garage that these are in has a 100 amp subpanel, then runs to my house 200 amp main panel via proper gauge wiring. 6 gauge copper wiring on the Nema 14-50. Not one bit of warmth anywhere while charging. I use off peak charging since it's less expensive, so it's set to start at 11pm to start. This means my solar shouldn't interfere with anything at all - I have 2 solar arrays that up the voltage during the daytime.

Not one bit of an electrical issue going on with anything else in my house / garage. What could this be?

 

[ucmndd]

It sure sounds like the common denominator is your home electrical supply if the car charges fine elsewhere.

I’d be interested to know if you get similar interrupts using the UMC on a regular 120v plug.

 

[BLH17]

It sure sounds like the common denominator is your home electrical supply if the car charges fine elsewhere.

I’d be interested to know if you get similar interrupts using the UMC on a regular 120v plug.

120V charging I have done in the past 2 months at other houses - 2 small issues on a Saturday when charging for 40-48 hours. Other house - no problem with the 120V.

If my outlet works great, all electrical connections are great, what could it be? I doubt it would be grounding - I have 4 ground rods (1 at 5.1kW inverter, 1 near subpanel by garage, 2 near back of house near meter/main). I wish I had a problem with something else electrical at my house so I could tell what's going on...

 

[SWIPE]

My guess is on a cable or the Wall Charger.
I would have them check the Wall Charger.

 

[240vPlug]

First I am assuming you no red lights on your wall connector just a session interruption. I would find a destination charger nearby that you can use to test the car charging at L2 charging speeds. 120v charging isn’t a good comparison. You have two chargers doing the same thing so it has to be either house wiring or the onboard charger in the vehicle. The odds of both chargers failing in a similar way would be pretty small I think. Use the destination charger to charge it for at least 90-120mins so you can narrow this down.

 

[BLH17]

I did see a red light a few weeks ago, but I set this to off peak charging so I don't see it and it's a detached garage so I can't easily see what's going on with the lights when it randomly stops charging. Last night it stopped 2x for instance, 11:23 after 23 minutes, then 12:54, then it charged it the rest of the way fine.

Going through what the 5 electricians did when they were here back in 2019, I did find one issue that doesn't add up to me - seems that the copper and aluminum grounds should not be under the same lug and should not be tied to the neutrals inside my Eaton 100 amp disconnect. Shouldn't those grounds be on a larger ground bar with big lugs tied to the case? Everything was approved and checked out by the city though!

Other than that I can't find any electrical issue anywhere...

 

[davewill]

I did see a red light a few weeks ago, but I set this to off peak charging so I don't see it and it's a detached garage so I can't easily see what's going on with the lights when it randomly stops charging. Last night it stopped 2x for instance, 11:23 after 23 minutes, then 12:54, then it charged it the rest of the way fine.

Going through what the 5 electricians did when they were here back in 2019, I did find one issue that doesn't add up to me - seems that the copper and aluminum grounds should not be under the same lug and should not be tied to the neutrals inside my Eaton 100 amp disconnect. Shouldn't those grounds be on a larger ground bar with big lugs tied to the case? Everything was approved and checked out by the city though!

Other than that I can't find any electrical issue anywhere...

Yes, I believe that tying the neutrals to the grounds in your disconnect could be the problem. It is very important the ground and neutral only be tied together at the main service panel. Since you have a 100a subpanel, there are probably circuits using the neutral at that point. This means the neutral in the subpanel will have return voltages on it. By tying the ground to the neutral in the disconnect, the ground to your EVSEs may not always be at ground potential like they should be. Either the car or the EVSE may be detecting this and throwing an error.

Take both grounds off of the neutral lug, and tie them to each other and the box.

 

[nghiaho58]

I agree with Davewill. Neutral wire and ground wire must not tied together at the sub-panel. They only be tired together at the first cutoff switch which is the main panel bey the meter. This could be the root of the problem. How did the electricians and city inspector passed this grounding at the sub-panel?

 

[BLH17]

Update to this:

After not changing anything, charging worked well starting at approximately mid October (8-9 weeks ago). I went with several weeks with zero interrupts at all, charged all the way to my setting no problem. I have even been charging at 30 amps most of the time instead of the 14-24amps I was trying to think it would help anything at all.

I suspect a stealth update fixed the issues. I went back to using my wall connector which used to have much worse and more often disconnects and it works just about flawlessly. I did have 2 interrupts 1-2 weeks ago but they were single and it started charging again on its own later.

My electrician finally showed up to separate the neutrals and grounds in the detached garage disconnect last week. Everything seems the same, no issues but I would like to get a few more weeks to see if I have any issue. I will try my mobile charger in the 14-50 sometime early next year just to see if I have issues with either 240V charging method.

If I do - it will have to do with the transformer, but like I said, this seems to be pretty much fixed from a stealth update from Tesla.