Typical Home Charge Rate

[Cottonwood]

The only way to reduce line losses is to put in bigger wires.
Your wires have the same resistance regardless of the current so 20 amps for 10 hours will give you the same loss as 40 amps for 5 hours (unless you are overheating the wires which is a different problem).
So, if you have properly sized wiring (or better still, oversize wiring) there's no need to reduce current. Your line loss will be the same.

Actually, not true.

The power dissipation in the wires is I^2*R, the current squared times the resistance. You are correct that the resistance can be reduced with bigger wire, but for any given wire size, the power lost to the wire's resistance falls as the square of the current reduction. The time to charge goes up linearly, so the total power lost in the wire for a given amount of charging and other resistive losses falls linearly with the current. As you get to very low charge rates, there are other overheads and inefficiencies that dominate, but the resistive losses continue to fall with current.

 

[Johann Koeber]

I have installed a three phase 32 A 230 V outlet and a charger in my garage. It gives me a maximum of about 22 kW - that is all the dual chargers in the S will take. Usually I turn it down to about 20 A - feeling it might stress the system and the car less (not sure about that).

Now we are trying to devise a control system that charges the car with whatever the photovoltaic system on the garage roof will supply. We have a 30 kW peak solar array. Priority is to be given to the energy needs of the house, next the cars, the rest being shunted to the grid.

Delivering electricity to the grid gives me about 0.13 € (ca. 0,17 US$) per kWh, buying energy from the grid is costing me twice that.

 

[nwdiver]

I have installed a three phase 32 A 230 V outlet and a charger in my garage. It gives me a maximum of about 22 kW - that is all the dual chargers in the S will take. Usually I turn it down to about 20 A - feeling it might stress the system and the car less (not sure about that).

Now we are trying to devise a control system that charges the car with whatever the photovoltaic system on the garage roof will supply. We have a 30 kW peak solar array. Priority is to be given to the energy needs of the house, next the cars, the rest being shunted to the grid.

Delivering electricity to the grid gives me about 0.13 € (ca. 0,17 US$) per kWh, buying energy from the grid is costing me twice that.

This is one of the upgrades that I REALLY hope Tesla makes available... initially it could just be a simple (8am = 5amp), (10am = 10amp) (noon = 15amp)... then back down again.

 

[TexasEV]

I have installed a three phase 32 A 230 V outlet and a charger in my garage. It gives me a maximum of about 22 kW - that is all the dual chargers in the S will take. Usually I turn it down to about 20 A - feeling it might stress the system and the car less (not sure about that

Reducing charging to 20A does not stress the car less. It just increases your electric bill because charging is less efficient at lower amps.

 

[Chris TX]

Yeah... I suspect there's a sweet spot... a rectifier and inverter operate in a very similar way and inverter efficiency curves look like this;

View attachment 64847

That's another reason I picked 20 amps vs 10 or 5... I wonder if Tesla is listening... wouldn't be the first time I got a call from customer service in regards to a post :smile:

Your picture makes it look like 40-45 amps is actually higher efficiency than the 20A you've selected. 10A might be too slow for some.

If that goes to 100A, there's a chance the gauge wire might be above 6AWG, too.

 

[Denarius]

I used to worry about charging my car at 80amps and how that would impact battery life. Then I supercharged and decided 80 amps was nothing as far as the battery is concerned and I stopped worrying about it.

 

[SW2Fiddler]

Hmmm.... I think at least 3 people missed the poll :wink: or they're LIERS! ......... :biggrin:

...or, like me, they are reading the forum via a mobile app (like Tapatalk). When not on a full-size computer screen, the app is more comfortable to use than scrolling a web-page screen. But the poll just does not show.
No lie

Rick