[piquadrat]

One drawback of charging on an 120v (or 230v) outlet is efficiency. While charging, the energy consumption of an electric car can easily reach 300-400 watts. When you're only charging with 1800-2400 watts, that's a sizeable amount of energy that never reaches the battery.

With a dedicated level 2 charger, you can charge with 10+ kW, making the percentage that is lost in the electronics of the vehicle much smaller.

[bonzini]

That doesn't match my experience. At 9-10A (2100W) the efficiency is way above 90%, meaning the consumption of the rectifier inside the car is more in the 100-150W range.

[mindslight]

> While charging, the energy consumption of an electric car can easily reach 300-400 watts

This is the first I'm hearing of this. Is this for real? Six modern desktop PCs worth of power, doing what? And that draw only occurs while charging, so it goes away when the car is "off"? Is this for heating the battery when it's cold? I'm not trying to jump on you, I'm just seriously surprised.

[piquadrat]

My source is an article from the ADAC, a German automobile association.

https://www.adac.de/rund-ums-fahrzeug/elektromobilitaet/lade...

They say 100-300W for the onboard electronics, and 15-25% total loss when using a wall socket (other losers contribute as well, e.g. cables that weren't originally meant to run at peak current for hours on time).

[mindslight]

If I'm reading that article/pictures right (using Doubleclick Translate), it's claiming that when charging at 2.3kW, 5-15% of the power is going to the 12V system. So assuming 90% efficiency for the main power converter and 80% efficiency for the 12V converter, that's at least 6-20 amps of draw on the 12V bus? That seems quite high.

Premises wiring seems like a red herring. At least in the US, conductors are sized based on a maximum percentage voltage drop at rated current, which means the branch circuit losses should be similar when using either one at full capacity. (A lower current circuit for a longer time is actually going to be slightly more efficient because the feeders are fixed sizes)

[bretto13]

It's also even more of a problem in freezing temps. I've charged with both a wall outlet and a 240v at home and at 15amps it will really struggle to heat the battery enough to charge. It gets painfully slow.

[redserk]

I agree that it isn’t the most efficient manner, this is not an insurmountable issue for the vast majority of people. The cost will still be well under half the price of gas for most people driving electric sedans and crossovers.

Yes, those living in the Bay Area with a Hummer EV will find the economics problematic but this solution is fine for the vast majority of other situations throughout the US.