Is charger more efficient at 220v?

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Well-known member
Aug 25, 2016
Does any one know if there is any difference in actual kw/h used to charge with 220v vs. 110v?
Well, using two different measuring "sticks," here is how much power I've seen used for 110v and 220v over the past few months (winter-spring-summer).

Going from empty (i.e., not running in EV mode) to full (i.e., charging cuts off), the maximum measured amount consumed on 110v (using a Ubiquity mFi to measure power) is ~8.3 kwh. The 110v charges were done using the stock portable charger that comes with the car. It pulls around 9A while charging and averages over 1 kwh per hour.

Similarly, on 220v, using a hardwired ChargePoint Home 25 32A, ChargePoint says the max consumed is 6.8 kwh. The ChargePoint app only reports plugged in time, not charging time so I don't have current draw or average kwh/hour info for that. Public ChargePoint 220v chargers run around 4 kwh/hour. In terms of total charging time, the max for 110v is 8:14 and 2:05 for 220v.

All that said, I don't fully trust either number. Testing the mFi with a light bulb leads me to think it overestimates power consumption. Given that a North American market E-tron will accept a max of 6.6 kwh, that means ChargePoint is close to 100% efficient converting AC to DC. Maybe I need more data to lock down both data sets.

For the sake of comparison, the GoM™ has displayed a high of 31 miles/50 km predicted range using both chargers. The GoM™ seems to give higher range numbers more often when charged on 220v vs 110v.
Interesting. My thought is to use the supplied Audi portable here at home, have been using it on 110v since we got the car last week. I have 220v circuit in the garage now, but will need either an adapter for the plugs (NEMA 10-30R to 6-50P) at ~$70US, or add a new circuit that has the outlet I need. Leaning toward the new circuit, as I could have it added in a spot that is more convenient for the front charging port on the A3. Would be nice if the Audi unit was more efficient in AC->DC conversion on 220v as well.
Arne, I assume the "Audi unit" to which you refer at the end of your post is the e-tron itself. I have only ever charged my e-tron at 230-250 vac so would be unable to comment on that aspect as all AC->DC conversion is carried out by the e-tron, as is the charging.
I guess I don't understand. If the AC-> DC conversion and charge happens on-board, what does the portable unit that came with the car do?