100 Amp and 50 Amp Service in my garage. Overkill?

[russman]

I thought charging at higher rate is more efficient. So charging at 80 is more efficient than 40, which is more efficient than 20.

 

[andrewket]

I can't find the graph. From memory- efficiency increases with higher amperages to 40A. The difference between 40 and 80 is negligible.

 

[hcsharp]

If you look inside a Clipper Creek EVSE, the circuit card is powered by a brick with a power draw on the order of a few watts. This isn't even a rounding error on the 19.2 kW you could draw at 80A, 240V.

There's no way any conceivable EVSE could draw 1A at 240V - that would be 240W. The thing would heat up like an oven inside. In the extremely unlikely event that the EVSE drew that much power, it would most certainly be designed with a pilot signal of 79A.

I think Tesla should simply draw the power that the EVSE reports.

The power supply in the Clipper Creek EVSE consumes way less power than the one in the HPWC. It's not 1A at 240V but it's a hog compared to the Clipper Creek unit, even when it's not charging. For those of us compulsive types trying to run our entire home and 2 cars on solar, we spend time chasing down these little vampire loads that run 24/7. When I built my own HPWCs I searched for an 80A contactor with a primary coil that draws less than 3 watts. The switching power supply and electronics are very efficient.

 

[Mayhemm]

The power supply in the Clipper Creek EVSE consumes way less power than the one in the HPWC. It's not 1A at 240V but it's a hog compared to the Clipper Creek unit, even when it's not charging. For those of us compulsive types trying to run our entire home and 2 cars on solar, we spend time chasing down these little vampire loads that run 24/7. When I built my own HPWCs I searched for an 80A contactor with a primary coil that draws less than 3 watts. The switching power supply and electronics are very efficient.

Interesting...now a quick question. The panel in my garage is about 2 feet from my HPWC, is there any harm in just shutting off its breaker when I'm not using it?

 

[andrewket]

Interesting...now a quick question. The panel in my garage is about 2 feet from my HPWC, is there any harm in just shutting off its breaker when I'm not using it?

Don't see why not, unless you're using scheduled charging.

 

[FlasherZ]

Interesting...now a quick question. The panel in my garage is about 2 feet from my HPWC, is there any harm in just shutting off its breaker when I'm not using it?

Some 50A breakers aren't rated for switch duty (i.e., aren't meant to be repeatedly switched on and off). Your breaker could wear out after a while and experience nuisance tripping.

 

[100thMonkey]

we installed a 125A sub panel with a 14/50 in the garage and a clipper creek out at the curb as part of the Sun Country Highway. having redundancy is great, I've even got a 10/50 additionally in the garage... in the age of transition away from gas, flexibility and redundancy is king. seeing up to 63 miles of rated range added an hour was exhilarating, that's nearly as fast as the Leaf on a DC quick charger. we charge the S mostly on the 14/50 but occasionally we arrive home and have a tight turn around departure and the added speed of the 80A's takes the stress out of the process.

 

[hcsharp]

Interesting...now a quick question. The panel in my garage is about 2 feet from my HPWC, is there any harm in just shutting off its breaker when I'm not using it?

As others have said, breakers aren't really designed for use as switches. A better idea would be to open up your HPWC and install a small switch that shuts off the 5/12v power supply and anything else that's always on. It seems like a lot of work though for what you'll save. There may be safety issues as well.

 

[Mayhemm]

As others have said, breakers aren't really designed for use as switches. A better idea would be to open up your HPWC and install a small switch that shuts off the 5/12v power supply and anything else that's always on. It seems like a lot of work though for what you'll save. There may be safety issues as well.

Yeah, I wasn't really that worried about it. I was just curious if it was a bad idea from an electrical standpoint. As you say, breakers are not switches. Probably best not to treat them as such.

Some 50A breakers aren't rated for switch duty (i.e., aren't meant to be repeatedly switched on and off). Your breaker could wear out after a while and experience nuisance tripping.

It's actually a 70A breaker. On a related note, when charging my S for the first time today it actually showed a rate of 58/56A for a while. Is this normal, or something I should be looking into?

 

[hcsharp]

Yeah, I wasn't really that worried about it. I was just curious if it was a bad idea from an electrical standpoint. As you say, breakers are not switches. Probably best not to treat them as such.

If you want to know how compulsive I am, my home-made UMC has a LCD with a backlight that draws 70ma at 5v (0.35 watts). I installed a small microswitch on the end of the box that turns the backlight off. :smile: OK to be honest a bigger motivation was the ability to make the whole thing go black if I wanted. Sometimes that's handy at night.

 

[FlasherZ]

Yeah, I wasn't really that worried about it. I was just curious if it was a bad idea from an electrical standpoint. As you say, breakers are not switches. Probably best not to treat them as such.

Some are rated "SWD" or "switch-duty" but typically these are only 15 and 20 amp single-pole breakers. My local church uses SWD breakers for all its lighting.

It's actually a 70A breaker. On a related note, when charging my S for the first time today it actually showed a rate of 58/56A for a while. Is this normal, or something I should be looking into?

Not normal. Watch carefully to see if it happens again and call service if you see it repeatedly.