Problems charging at 110v on GFCI circuit

[Feathermerchan]

So some here are assuming that when level 2 charging, 80% of the circuit capacity is always used. It isn't necessarily so. I have two 50A circuits for EV charging. I have my Model 3 and Y set for about 20A because that's all that's needed when charging overnight. It's easier on the grid and generation too. We typically only charge on Sunday and it's enough to take us thru the week.

 

[leonar40]

So some here are assuming that when level 2 charging, 80% of the circuit capacity is always used. It isn't necessarily so. I have two 50A circuits for EV charging. I have my Model 3 and Y set for about 20A because that's all that's needed when charging overnight. It's easier on the grid and generation too. We typically only charge on Sunday and it's enough to take us thru the week.

I was doing the same thing when I first got my car. Charging at a lower rate means less heat in the wall charger and cable, etc so I assumed better. But several people mentioned that it's more efficient to charge as fast as you can because the car has to run some background loads anytime it's charging such as fans, pumps, the computer, etc. The less time that you can have those things running, the more efficient your overall charge will be because more of the current will be actually going into the battery. Now I charge at 32A even though I could easily get by with 16A for most nights.

 

[Feathermerchan]

When I charged at 40A (I have Gen1 UMC) the #6 Romex in the hot attic got pretty warm to the touch. I did not like that so I backed off to 30A and the heat is undetectable. Though there are loads that run during charging, there is also losses in the wire and the batteries that may reduce the optimum current for efficient charging ie using the fewest kWh from the grid to put the most kWh in your battery.

 

[Rocky_H]

I was doing the same thing when I first got my car. Charging at a lower rate means less heat in the wall charger and cable, etc so I assumed better. But several people mentioned that it's more efficient to charge as fast as you can because the car has to run some background loads anytime it's charging such as fans, pumps, the computer, etc. The less time that you can have those things running, the more efficient your overall charge will be because more of the current will be actually going into the battery. Now I charge at 32A even though I could easily get by with 16A for most nights.

You say this as if one thing disproves the other. That's not so. Those are two true things, which are two separate topics.

Using your charging equipment at its maximum level every day and creating that heat is a lot of heat cycling from hot to cold to hot, etc. very often. That is shortening the life of the equipment. With electronics that kind of heating and cooling causes metals and connections and solder points to expand and contract as the metals change temperature. That eventually stresses the metals and can make them degrade and become brittle or break connections. Also, there are the things people have mentioned, where sometimes these products are built to just barely function and pass running at their maximum level, but over the long term, for years, that heat can eventually burn and melt things.

But that is a different topic than how is the efficiency and energy lost in the charging cycles. And that doesn't have to be an all or nothing situation. Sure, charging at very low levels, like 120V and 12A is going to be very wasteful. But if you are using a 240V outlet and maybe running it turned down a little bit, to 26A instead of 32A, that is saving some heat, but still pretty decently efficient.

 

[Uncle Paul]

If you are charging overnight, it is most always going to get enough charge, even if lowered to a rate where all wiring is cool to the touch.

 

[carrmichael]

FYI, I had the same issue as the original poster on this thread— GFCI outlet would trip after a few minutes using standard 110 adapter.

This was happening in an exterior location that I had used for several years with no problems, until the GFCI went bad (wouldn’t reset). I replaced it with a high quality Leviton GFCI receptacle and then it started tripping. The wiring was fine and other lights and appliances were not tripping the outlet. Only the Tesla tripped the outlet and only after the initial ground check cleared and it started charging.

After reading this thread, I replaced the GFCI with a lesser quality outlet (one that came bundled with an exterior outlet cover), and now it’s working fine.