Max Charging Level 2

[ruddyone]

Just a quick question. (newbie here) What is the max charge that the i3 will accept from a L2 charger? From the specs, it looks like something approaching 7.4kW. At chargepoint stations I ususally get around 6.2kW.

Anyway, was looking at home chargers and saw some that claimed they provided 9.6kW. But, don't know if I could actually take advantage of that or not.

Thoughts? Feel free to educate or point me to the right locations.

 

[janner]

At 240 volts and 32 amps, a level 2 charger will deliver 7.22kW.

http://avt.inl.gov/pdf/fsev/SteadyStateLoadCharacterization2014BMWi3.pdf

 

[ruddyone]

Thanks Janner. I was looking at a L2 that was 50Amp with 240V. The label said it would do 9.6kW. But, when I look at the i3 specs, it looks like the max it can accept through an L2 is 7.4kW.

Is that true?

 

[I33t]

The car will only take what it can regardless if the EVSE is capable of more. I have a 40A 240v EVSE but the car still charges at it's maximum rate of about 32A.

 

[alohart]

At 240 volts and 32 amps, a level 2 charger will deliver 7.22kW.

http://avt.inl.gov/pdf/fsev/SteadyStateLoadCharacterization2014BMWi3.pdf

That reference measured the maximum charging amperage at 240 v. to be 30.1 amps. 30 amps is the maximum continuous current that a North American i3's charger can request. I have read that the maximum current in European versions is stated as 32 amps. I suspect that the North American and European chargers are identical and that this difference is somehow related to a different method for stating or measuring current.

Many public charging stations in the U.S. operate at 208 v., so the maximum charging power would be 6.2 kW as the OP has experienced. Residential electrical service provides 240 v., so the maximum charging power using a Level 2 EVSE installed at one's home would be 7.2 kW if the EVSE can supply at least 30 amps. A Level 2 EVSE that is capable of supplying more than 30 amps would not charge an i3 any faster. However, future EV's will likely be capable of charging at higher power (a Tesla can already), so a Level 2 EVSE that can charge at greater than 7.2 kW would be a form of future-proofing.

 

[jadnashuanh]

European specs are rated at peak, US specs are rated at average. The car can use up to 7400W, and it depends on what your ACTUAL voltage is, and the EVSE's pilot signal as to how much the i3 will use. The car will never try to use more than the EVSE announces it has, but it will only accept up to it's maximum...sort of like plugging a 100W light bulb (about 0.8A) into a 15A circuit...it doesn't draw more than it needs, and the car is smarter, because it adjusts that based on what's available. That's why it also works with the EVSE that comes with the car, and that only can provide 12A maximum.

FWIW, my typical supply voltage ranges about 245-248vac, so I can often get the max with my 30A EVSE. Many of the public EVSE's in the USA have a 208vac supply. Power=volts*amps.

When planning on the supply wiring, keep in mind if the EVSE is capable of supplying 50A, then you need 125% of that for the supply wiring and protection device (typically a circuit breaker). Many homes will have trouble dedicating that much power to a new device. One reason why I went with a 30A device, while potentially a larger one might be good in the future for a vehicle with a larger on-board charging circuit. It will still work, just take a bit longer. Since normally, that's overnight, there's plenty of time.

 

[ruddyone]

Really informative. Thanks all.

I'll probably just go with a Clipper Creek or Bosch.

 

[Blue20]

If I remember my physics class correctly, AC voltage is measured by RMS value. Average voltage of AC current is 0.

Europe spec is one sine wave on the live wire. In NA, there are two sine waves moving 180 degree out of phase to make up the 240V.

 

[jadnashuanh]

If I remember my physics class correctly, AC voltage is measured by RMS value. Average voltage of AC current is 0.

Europe spec is one sine wave on the live wire. In NA, there are two sine waves moving 180 degree out of phase to make up the 240V.

We're talking current here, not voltage. The way they measure current between the two areas is different. What is the same is that the i3 can process a maximum of 7400W of input power. Given Europe tends to use 220-230vac and the nominal standard in the USA is 240vac, to achieve 7400W input, you need more amps in Europe to achieve the same power consumption.

 

[ted99]

Bear in mind that residential voltage in the US is not universally 240 v. It can be anywhere between 208 volts and 240 volts. It depends on the transformers used by the local utility to reduce the distribution voltage to the breaker box voltage.

 

[PhilH]

Given Europe tends to use 220-230vac and the nominal standard in the USA is 240vac, to achieve 7400W input, you need more amps in Europe to achieve the same power consumption.

This isn't generally true. The specification for Europe is 230 volts +10% - 6%, but that's to allow for the UK's standard voltage of 240 and much of continental Europe at 220V. Ours is currently 239.8V.

 

[rbi3]

The car will never try to use more than the EVSE announces it has

So we can leave the Level 2 charging setting on "Maximum"?

 

[jadnashuanh]

The car will never try to use more than the EVSE announces it has

So we can leave the Level 2 charging setting on "Maximum"?

The only time changing the car's maximum charging rate is likely to be useful is if the thing it is plugged into might have something else on the circuit meaning that it might then blow the fuse or pop the circuit breaker of the line feeding it. AN example might be using the level 1 EVSE in the garage, and the receptacle was also feeding the garage door opener (or anything else that might have a surge or constant power use) that would pop the breaker. I suppose if your level 2 unit was on the same circuit as your dryer, or some such, that might be important, too. Otherwise...what happens is that the EVSE sends out a signal announcing how much power it has, and the i3 then decides how much it wants to use, never exceeding what is announced.

 

[rbi3]

The car will never try to use more than the EVSE announces it has

So we can leave the Level 2 charging setting on "Maximum"?

The only time changing the car's maximum charging rate is likely to be useful is ...

Great ... thank you!

 

[NZi3]

Hi,

I use and like the capabilities of the EVSE from https://emotorwerks.com/ they are also very well priced given the capabilities.