What's the bare minimum required for an EV charger in cold climate?

How many KM a year do you drive? This will help me better answer your question. I don't care if you plan on taking the occasion long trip.

FWIW two years ago I hardwired my Emporia using 6/3 Romex on a 60A circuit and it has been plenty for my needs. I even derated it to 32A because that was more than enough for my weekly commutes.

Here is a pic of the Emporia EVSE after I did the installation.


And here it is charging the Mustang for the first time.

I don't think you need to worry about it unless you are charging at 120v.

When we built our garage three years ago I planned a 60 A panel for it, based on the fact that a common EV charger type is up to 40 A. Since I was going to run buried cable out to the garage from the house (about 140 ft of cable), I checked with a contractor for that installation part. He advised that future changers are headed to 60 A, and might even go higher, so I should consider a 100 A panel and feed cable. Like you, I winced at the cost of that! Shortly after as I consulted an electrical inspector on another matter he advised I check the price of Aluminum buried cable instead of copper for a much better price, so I asked the contractor for a revised quote. He came back surprised at the difference. Going that way at 100 A feed versus 60 A in copper cable, the saving was more than enough to pay for the larger 100 A panel in the garage. So that's what I did. As it happened, when I got it done, the local supply houses did not have 00 Aluminum buried cable in stock, so they got 000 for a sightly higher price. That is rated for 115 A, but if you de-rate that for the cable length it's 105 A. With the light other uses in the garage (no heavy equipment), I could install two 40 A chargers (we have three cars in the family) or one really heavy charger - whatever is needed for future car purchases.

Don't forget this factor. Although a charger may actually deliver 30 A current to the car, it is rated at 40 A in terms of the wiring required. That is because a general "rule" in wiring is that the circuit should be designed so that the NORMAL sustained max current does not exceed 80% of component capacity. For example, a common laundry electric dryer with a 4000 W heating element needs 18 A for the heater plus 10 A for the ¼ HP motor, total 28 A max sustained current in operation. That requires at least a 35 A cable and breaker from the panel.

Red Squirrel said:

Not really sure how many per year, but the most I do in a day might be like 200 or so, if I go to my off grid property and back. A typical day might be like 30ish if I'm just going to work and go home for lunch and do errands etc.

The time it takes to charge is not something I would worry about as I would do it overnight, I just wouldn't want to be in a situation where the battery heater is using all the available power and it can't charge at all. Not sure what is minimum to ensure that doesn't happen. Keep in mind we get -40's here and it would be outside in the wind.

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I just had a "Oh, duh" moment at work today when on I was on my break reading your post. Anyway, you don't have to worry about cold temps affecting your battery charge time or amps needed. Both Ford EVs will continue to keep the battery at a safe temperature even when not plugged in. The built in computers monitor the outside ambient temperature and if it is cold enough they activate the onboard heating system to keep the battery warm.

I think a 30-32A draw on a 40A circuit would be fine for you. Even if you get home and the temps are cold the battery management system heating system only draws around 2-3A total IME.

No, even when parked and the vehicle is off if the BMS determines the ambient temperatures are to cold it will activate and warm the battery. It uses so little power though it would take weeks or months not days to run the battery down. I've been an EV owner for around 2.5 years and never heard of this leaving someone stranded.

Running 6/3 isn't a bad idea but just remember at least here in the US code only allows 6/3 Romex to run at a max 44A continuous load on a 60A circuit. If you are running metal clad or THHN wire in conduit then you are allowed the full 48A on a 60A circuit. I know you're Canadian so codes are most likely different for you but I just wanted you to be aware.

That plan looks good to me. Using the 6/3 cable (Copper) from panel to exterior mounting box would be OK, although technically not necessary. There is no regulation that says you cannot use a wire gauge too large. Then the actual limit of power for the charger would be imposed by the panel breaker that feeds that outlet and by the amp rating of the socket fixture you mount there. Both of those you can settle at the time you install the charger.