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by mindslight 755 days ago
> 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.
1 comments
piquadrat 755 days ago
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).

link
mindslight 755 days ago
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)

link