48 Amp Charging Setup Question

[MacO512]

Because it's not that difficult of a setup and was seeking advice, I should have clarified that I'll be utilizing powersharing. If anything I'll set the power-sharing to 44 amps and call it a day. Safe for 6/3 romex and won't burn my house down.

If it's "not that difficult" why are you asking for advice on how to do it?

Your comments have proposed actions that are in violation of electrical code, so it appears this is difficult for you to handle.

 

[Mrbrock]

As others have stated but you appear to not acknowledge, there is no 44A Wall Connector setting. There are settings for 15 (12), 20 (16), 30 (24), 40 (32), 50 (40) and 60 (48). So you put 50A breakers everywhere and your total power sharing is limited to 40A.

 

[dgbehrends]

You can use 6/3 MC which is rated for 75Amps I believe. I had an electrician install it to my gen3 charger using a 60amp breaker in my panel. If I get another EV I plan to power share with another gen 3 charger off this same 60amp breaker (my panel is full). To do this I need to install a 60amp panel in my garage using the same 6/3MC coming from the 60amp breaker in my main. In this 60amp panel I would install two 60amp breakers each running 6/3MC to each gen 3 charger. Then I setup the chargers to power share and the two of them together will not draw more than 48amps. I felt the 6/3MC when the car was charging and it is slightly warm. The 60amp breaker gets very warm, I would almost say hot. Not too hot to the touch but close. It was a standard breaker. I might look to upgrade to a more expensive/ higher quality 60amp breaker in the near future.

 

[Mrbrock]

You can use 6/3 MC which is rated for 75Amps I believe. I had an electrician install it to my gen3 charger using a 60amp breaker in my panel. If I get another EV I plan to power share with another gen 3 charger off this same 60amp breaker (my panel is full). To do this I need to install a 60amp panel in my garage using the same 6/3MC coming from the 60amp breaker in my main. In this 60amp panel I would install two 60amp breakers each running 6/3MC to each gen 3 charger. Then I setup the chargers to power share and the two of them together will not draw more than 48amps. I felt the 6/3MC when the car was charging and it is slightly warm. The 60amp breaker gets very warm, I would almost say hot. Not too hot to the touch but close. It was a standard breaker. I might look to upgrade to a more expensive/ higher quality 60amp breaker in the near future.

I could be way off base but there is usually only 1 type of breaker recommended for your panel made by the company that makes the panel. They usually don’t offer heavy duty versions of the same breaker type. That being said, most rated ampacities are at least 60C (140F) and as high as 90C whitch is 194F so that would definitely be hot to the touch.

 

[dgbehrends]

I just measured the temp with a heat temp gun and it was at 105F. I looked up my receipt from Graybar electric and it's a
Square D - QO260CP QO 60 Amp Two-Pole Circuit Breaker made by Schneider Electric also known as QO
A google search and some review reading leads me to believe it's a high quality breaker so I can sleep a little better at night.

​

 

[MacO512]

I just measured the temp with a heat temp gun and it was at 105F. I looked up my receipt from Graybar electric and it's a
Square D - QO260CP QO 60 Amp Two-Pole Circuit Breaker made by Schneider Electric also known as QO
A google search and some review reading leads me to believe it's a high quality breaker so I can sleep a little better at night.

​

Yes it's a good quality breaker. All brands are pretty good though.

My Tesla WC cable to the car feels a bit warm charging at 40 amps so I lowered to 30 in the car. Hoping it might be a bit more efficient and reduce long term wear, who knows.

Personally I'd probably run amps lower if my breaker was hot like yours. Not sure how well these breakers are designed to run for years at such a high load. But probably over cautious on my part. Heck even if breaker fails it likely easy or cheap to replace.

 

[240vPlug]

Yes it's a good quality breaker. All brands are pretty good though.

My Tesla WC cable to the car feels a bit warm charging at 40 amps so I lowered to 30 in the car. Hoping it might be a bit more efficient and reduce long term wear, who knows.

Personally I'd probably run amps lower if my breaker was hot like yours. Not sure how well these breakers are designed to run for years at such a high load. But probably over cautious on my part. Heck even if breaker fails it likely easy or cheap to replace.

The heat in the cable is normal. There will be some warmth in the wires and breakers too. The breaker should interrupt power delivery if there is too much current or too much heat. If everything is working properly an undersized wire should result in frequent tripping of the breaker due to excessive heat.

The heat is from the power lost during delivery to the battery.

 

[Art84]

I could be way off base but there is usually only 1 type of breaker recommended for your panel made by the company that makes the panel. They usually don’t offer heavy duty versions of the same breaker type. That being said, most rated ampacities are at least 60C (140F) and as high as 90C whitch is 194F so that would definitely be hot to the touch.

True. And just for your information, the human hand can keep the hand on hot objects up to about 50C. Anything hotter than that - you ll not be able to continuously touch and hold your hand on that thing.
So if you touch your cable or breaker and feel that it's like "very warm", it means that your are about 30-40-ish degrees range which still far of the rated ampacity of 60C

 

[MacO512]

The heat in the cable is normal. There will be some warmth in the wires and breakers too. The breaker should interrupt power delivery if there is too much current or too much heat. If everything is working properly an undersized wire should result in frequent tripping of the breaker due to excessive heat.

The heat is from the power lost during delivery to the battery.

If there is heat generated that is power lost and not charging the car.

I suspect heavier guage wire/connections will have less resistance so less voltage drop and less heat so they will waste less electricity.

I can't change the guage wire of the Tesla handle. The THHN 6 guage wire I have is only about 15 feet to the main panel so probably pretty efficient.

Only thing I can really control is amps the car is charging. 30 amps is less heat than 40, so I was thinking it might be a tad more efficient. But then it's charging for more minutes so maybe it's a wash or actually less efficient.

I'm sure I'm splitting hairs with this and it doesn't really matter significantly. However if would be interesting to know what is most efficient.

I did hear one argument which seems logical for not charging at 120volts. It's that your pulling an unbalanced load from only one phase. It's likely more dollars as service is billed for total amps wherever it's 120 or 240 volts.

 

[dgbehrends]

If there is heat generated that is power lost and not charging the car.

I suspect heavier guage wire/connections will have less resistance so less voltage drop and less heat so they will waste less electricity.

This is interesting. My run was 50ft, 4/3 NMB was $11/foot, 6/3 MC was $5.5/foot That's a lot of money to overcome. I was getting a charge of about 44miles per hour at 48amps. 11cents/kw The Tesla wall charger cable was just as warm as my 6/3 MC.

 

[dgbehrends]

This guy summed it up well. Aluminum wire for Tesla wall connector

 

[bowenj10]

The 100 amp panel will never see 100 amps as I'll be utilizing powersharing and the most it will ever see is 44 amps which is 80% of the 55 amps 6/3 can hanhandle

Late to the thread hwre and I'm sure this is too late, but I figured I'd chime in.

What you plan to do after the panel is irrelevant when it comes to how the panel needs to be wires.

Your panel is a 100A panel. It needs to be wired and breakered as a 100A panel should be. Unless you have a crystal ball that accurately tells the future, you don't know that the 100A panel will never see 100A. What if you get hit by a bus and the next owner looks at it as a 100A panel without checking the wires and plows forward with adding two non-power sharing 48A chargers?

 

[mongo]

Late to the thread hwre and I'm sure this is too late, but I figured I'd chime in.

What you plan to do after the panel is irrelevant when it comes to how the panel needs to be wires.

Your panel is a 100A panel. It needs to be wired and breakered as a 100A panel should be. Unless you have a crystal ball that accurately tells the future, you don't know that the 100A panel will never see 100A. What if you get hit by a bus and the next owner looks at it as a 100A panel without checking the wires and plows forward with adding two non-power sharing 48A chargers?

In general, you can feed a subpanel with a main breaker from a lower amperage breaker. The main then just acts as disconnect.
50 amp breaker at main feeding a 100 amp sub panel

 

[paulk]

It is absolutely safe and normal to connect a 100 amp capable panel to a lower amperage breaker. If you want to feed a 100 amp from a 60 amp breaker, go right ahead. Just don’t put any circuits on it bigger than 60 amps.