3 phase charging of 60Ah 2014 model with 7,4kW onboard charger

[janulo]

Hi, did anyone try to charge i3 model with single phase input (which can take up to 32A) from 3 phases? I have 2014 model with 7,4kW single phase onboard charger. At home, I have 3x230V available, with main circuit breaker rated at 3x25A. Therefore I’m not able to reach full charging power.
I was thinking what about “merging” of 3 phases into single one using 3phase rectifier and supplying DC output from rectifier into car AC input. As it goes to onboard rectifier anyway, the car should not complain? In this way, I can provide full 32A to car, while taking approx 11A from each input phase (plus some losses). So that’s theory, but what is your experience or recommendations? I was thinking to put this rectifier either before EVSE or behind, depends if EVSE will complain about DC voltage instead of AC.

 

[jadnashuanh]

The modules are too expensive to risk it IMHO. WIthout knowing a bit more about the internal operation, you could end up burning one or more out.

 

[janulo]

The modules are too expensive to risk it IMHO. WIthout knowing a bit more about the internal operation, you could end up burning one or more out.

Exactly, without knowing more I could burn it. That’s why I’m asking if anyone did that or have proper knowledge I won’t dare to risk it.

 

[jadnashuanh]

What voltage do you get if you measure across one phase to another? I'd guess, probably 220-vac or so? A few EVSE devices have internally programmable pilot signal levels so you can match the supply to the signal sent to the vehicle, so you don't overload anything. There are settings in iDrive to limit how much the vehicle draws, but that may not give you the resolution you want.

The US residential power is 240vac, and the transformer is center tapped, and we use that as neutral and reference it to ground for our normal 120vac sockets. 240vac is used more for primary loads like a dryer, water heater or stove. Most everything else runs off of 120-vac. Those that use 220-240 for 'normal' things, do not have the neutral connection. It depends on how the transformer supplying power is wound what voltages you'll get.

Most of the i3's sold only have two power pins...a few countries use the variant that supports three phase inputs and they can handle a higher charging rate than those using only two.

 

[janulo]

Voltage between phases could be the main issue here. We have grid with grounded Neutral point. Voltage of each phase against Neutral is 230V AC, while voltage between phases is 400V AC. And AFAIK three phase rectifier does not use Neutral at all, therefore works with 400V. Standard charging of car uses now with 230V. So maybe after rectifying some step down regulator or even DC/AC inverter with 230V AC output will be needed. In such case it won’t make sense

Another option could be to replace the cabling, so two on board chargers will be fed from two different phases instead of being connected both to single phase. But that will probably require also some coding.

It’s not that simple as it looked in the beginning, but it could be quite useful if there is a feasible solution.