level 2 24 watt charging time

[i3guy]

My wife just got a 2019 i3s. She drives very little. we have 240 power on a desginated circuit for a generator thats easily accessible for charging purposes. I have a charger that allows multiple ranges from 16w to 40w. without having to rewire the whole thing at this time, I would probably set in up for 24w charging. I'm afraid that setting for 32w might require rewiring the whole thing, or at the very least require changing 30 breaker to a 40 amp. (just have to change the outlet to NEMA 14-50)
My question is how long will this take to charge at this rate. I can live with 4-6 hours

 

[mojo]

I guess you must be mixing up Watts and Amps? You refer to a 40A circuit breaker, but then talk about setting the charge rate to 24W.

In simple terms, Amps x Volts = Watts. So in this instance, setting the charging current to 24A corresponds to just under 6kW of power consumption during charging.

The time to charge at various charging rates will depend on the charging equipment fitted - both inside and outside of the car - and the size of the battery (which you don't state).

For a 2019 car I would expect it to be capable of 7.2kW AC charging - which means that there is no point in trying to go over a charge current of 32A as the car can't take any more than that.

As already said, the time to charge depends on the battery size - I think a 2019 car could either have had a 94Ah or a 120Ah battery, with proportionately longer charging times for the latter.

 

[mojo]

I should add that if you are planning to use a typical (inline) Mode 2 "granny" charger such as the one that BMW supply with the vehicle, you can't expect to get anywhere near a 32A (or even a 24A) charging current.

A typical inline box of that type is rated at 2.4kW, so it won't allow the car to take any more than 10A.

[Edit - but this probably isn't relevant, as you seem to have a wall box charger.]

 

[EvanstonI3]

Your car has a 120ah battery which has a max capacity of 42kWh but probably a max useable capacity of 38.
If you are charging at 24amps instead of 32, that is 75% of max.
75% of 7.2kWh (max rate for L2 @ 32amps) that's 5.4kWh.
From zero it would take about 7 hours to charge from completely empty at 24amps, but since she drives "very little" chances are you will not be waiting that long.

My neighbor has a 2019 and also drives "very little". They only have a 120v L1 charger and it has worked fine for the last 2 years as they just leave it plugged in all the time.

 

[SSi3]

Your car has a 120ah battery which has a max capacity of 42kWh but probably a max useable capacity of 38.
If you are charging at 24amps instead of 32, that is 75% of max.
75% of 7.2kWh (max rate for L2 @ 32amps) that's 5.4kWh.
From zero it would take about 7 hours to charge from completely empty at 24amps, but since she drives "very little" chances are you will not be waiting that long.

Can confirm all numbers here... this is exactly my setup. Was limited by my 100A panel, so could only run a 30A circuit to the garage, works great!