Charging problems

[Transplant]

We got our new Model S last week and have had daily problems charging it at home. (No problems charging with a supercharger or ChargePoint.) We had an electrician install a Nema 14-50 with a 50amp breaker using 125ft of 6ga copper. It absolutely refuses to charge at 40A and it automatically selects 32A instead. It will charge for 15 minutes to an hour before shutting down with a "Charge cable fault, check the power" message on the dash. We have a little better luck by manually setting it to 24A but it is still unreliable.

Last night, the charge cable went completely dead. There are neither green nor red lights and it won't even open the charge port.

I verified that there is power at the outlet and I also tried plugging into a 120v outlet with the same result; the cable seems dead. Then I checked the wiring in our service panel and noticed that the electrician had connected the neutral white wire to the ground bar instead of the neutral bar. Those two bars are connected together but only with a 12ga copper wire.

So finally, the question: Does the charger actually run a significant amount of current on the white wire? Is there any chance this minor wiring error could be the root of our problem? Is it common for charge cables to die?

 

[trm2]

Are you using the mobile connector that came with the car? If so, it is limited to 32 amp charging.

Also, your electrician should fix what he screwed up.

 

[drklain]

You should call the electrician to fix the wiring, but your problem is that the mobile connector will only carry 32 amps no matter what the circuit you installed. So it is working as designed and giving you the maximum it can deliver. In charging, you will charge at the lowest of:
- what the car can accept
- what the circuit will deliver
- what the cable can deliver

If you install a Tesla wall charger, your car should get the full 40 amps. That said, the 8 amps of difference don't mean a huge change in charge rate. Many people accept the 32amps via wall connector to save money by not buying a wall charger and because they will will easily get the required daily charge each night. In. Y case, I have my car to start charging from the wall connector (40 amps) every morning at 5 am and am charged up to my daily charge level by 7 every day. If I drove mor and need more charge, I just set the car to start charging earlier.

 

[Transplant]

Thanks. I didn't realize the mobile connector was limited to 32A. All I knew was that Tesla recommended a Nema 14-50 with a 50A breaker and the 75% rule would limit current to 40A. That's pretty misleading...the 14-50 implies you are using the mobile connector, not so?

I agree that the 32A is fine for what we need. In any event, Tesla gave us a new mobile connector today, I moved the neutral wire to the neutral bus where it belongs, and the car recharged perfectly without a glitch.

One last problem. When the car finishes charging, it must be causing some sort of power surge because our induction range freaks out with an F68 error code and we have to go reset it's breaker.

 

[drklain]

The induction range issue sounds odd. It may be that the breakers are next to each other and you're getting some sort of power spike or voltage drop that is affecting the induction range. Not sure what the F68 error code is, but that may help you in diagnosing it.

Generally the heavy load items are split on two sides of the breaker panel. Not sure how your panel is wired, but there may be opportunity to relocate one breaker to the other side if this is the source of the issue.

I have an induction range as well and have had no impact on it (or anything else) from the wall charger...

 

[Snobun]

Newer S after 12/15/17 comes with Gen 2 UMC which max out at 32A. That’s why you cannot set it to 40A. Anything before 12/15/17 comes with Gen 1 UMC that can max at 40A.

 

[ucmndd]

Sounds like you had a bad UMC for sure.

I’m not an electrician but I’m reasonably certain it’s perfectly fine for neutral and ground terminations to be co-mingled at your main service panel (NOT at a sub panel). as you mention the bus bars are bonded together so same is same.

 

[TMeister]

...

I’m not an electrician but I’m reasonably certain it’s perfectly fine for neutral and ground terminations to be co-mingled at your main service panel (NOT at a sub panel). as you mention the bus bars are bonded together so same is same.

This is correct. Just remember only in the main panel.

 

[Transplant]

Yup, the neutral and ground aren't connected in sub panels, only in the main panel.
Curiously, the breaker for the induction range and the mobile connector just happen to be at opposite ends of the panel. Whether they are on the left or right side of the panel should not matter since both of them are 240v and hence they both use both sides - there's no choice.

Our induction range had problems when we originally installed it. It kept faulting out with error F68 which means problems on the power line. The dealer put on a spike filter and the problem went away - until we got the Model S. So it's most likely some oversensitive protection circuitry on the induction range.

 

[drklain]

Makes sense. I've never seen that with mine...

 

[whitex]

This is correct. Just remember only in the main panel.

You still shouldn't be running neutral wire to the ground bar. While it may "work", the connection between neutral and ground in the main panel may not be (and likely isn't) rated for the full panel current (in OP's case a 12AWG wire which is definitely not meant to pass full 200A or 400A main panel max, not even 50A with 12AWG btw). There is a reason why the two bars are separate in the panel.

 

[_jal_]

The neutral is the center tap off the transformer coil for the neighborhood. These are usually grounded just for simplicity, but it is possible to get a ground loop if the ground at your house is different than other places around the neighborhood. This is likely not the issue. I have a gen 1 charger and it doesn't even use the neutral pin.

If you've tried it on a 120 outlet that another appliance works with and it doesn't work, then it's almost definitely the UMC.

As an aside, I just learned from the post above that they limit the new UMCs to 32 amps. That's a pretty big step down.

 

[whitex]

As an aside, I just learned from the post above that they limit the new UMCs to 32 amps. That's a pretty big step down.

I thought that was for Canadian UMC's only. I tested an early 2018 US UMC and it goes up to 40A. Got a new car coming by end of this month, hope it's not a 32A charger. While it doesn't make a difference every day, it does sometimes.

 

[TexasEV]

All cars are being shipped now with the gen2 charger that only goes up to 32A. Search TMC for dozens of posts on this topic. You can see pictures of the new style connectors on Tesla’s charging web page.

 

[whitex]

All cars are being shipped now with the gen2 charger that only goes up to 32A. Search TMC for dozens of posts on this topic. You can see pictures of the new style connectors on Tesla’s charging web page.

I searched for "umc usa 32A" and all I got was Canadian ones and some Europe. Do you have the USA thread link handy?

 

[TexasEV]

I searched for "umc usa 32A" and all I got was Canadian ones and some Europe. Do you have the USA thread link handy?

Here’s one of the threads:
New UMC 14/50 limited to 32 amps... WHY?!

 

[whitex]

Here’s one of the threads:
New UMC 14/50 limited to 32 amps... WHY?!

Thanks. I see the pictures and it's the Model 3 charger that now apparently ships with Model S? I guess we got lucky with our 2017 Model S as it came with the gen1 charger. 2018 is being built now, let's see which charger it comes with.

 

[Buddyroe]

125' + the length of the charging cord. I'm not electrician, but there is definitely a limit on the length you can run. Maybe one of the more expertise posters can chime in.

I know when I first installed my 14-50 outlet, I used 14' 6-3. Then I later added a 35' RV extension cord. The first couple of times I used it, for some reason, it gave the same error you got. I had to move the amps to 32. But then one day, I decided to see if it would work on 40 amps again, and lo and behold, it did. Never had the issue again. I'm not exactly sure what changed.

 

[TMeister]

Yup, the neutral and ground aren't connected in sub panels, only in the main panel.
Curiously, the breaker for the induction range and the mobile connector just happen to be at opposite ends of the panel. Whether they are on the left or right side of the panel should not matter since both of them are 240v and hence they both use both sides - there's no choice.

Our induction range had problems when we originally installed it. It kept faulting out with error F68 which means problems on the power line. The dealer put on a spike filter and the problem went away - until we got the Model S. So it's most likely some oversensitive protection circuitry on the induction range.

Some research on your F68 error indicates this is set under high voltage conditions. Check your 240 volt service. It could be at the high end of acceptable range and then when your car charging stops there is a high enough voltage increase to cause the oven to set F68. 252 volts is usually the utility upper range so they will claim anything delivered to the house between 228 and 252 is OK. Your oven may be more sensitive.

My energy monitoring system shows wide variability in supply voltage throughout the day. One can actually see generators coming on and off line as the voltage moves around. A typical day at my house sees 242 to 250 as the range. My induction cooktop (A Kitchenaide) tolerates those voltages. The utility transformer I share with 3 other houses is a 7200 v primary and has a 35 ft drop to my house.

 

[dcmetro]

I wish they still kept the cables to not max out at 32Amps. Service told me cost was the reason they went with Gen2. I wouldn't mind switching Gen2 with Gen1 cable, if I could.