Although a very happy i3 REX owner for a few months now, it's always been bugging me that the i3 can only charge using one phase. 32A outlets are not so common here in the EU, although I'm currently able to pull 20A from a 32A circuit at my work without blowing too many fuses
It would be perfect to do multiphase charging, allowing for faster charge times on a 3x16A outlet. So... here's the nerdy and quite theoretical part :ugeek:
I'm an electrical engineer, and as such of course interested in the inner workings of the i3. Looking into the tech docs available in the global i3 facebook group, it seems that 32A / 7.4kW charging is actually handled by two chargers in the i3. One 3.7kW charger in the EME (electrical machine electronics, present in all models), and one 3.7kW charger in the KLE (convenience charger). The KLE seems to have had some problems as from what I can read in this forum, but hopefully they're fixed by now. As I understand the document, not all i3s are fitted with a KLE, but it will be there if the DC option is chosen.
The interesting part is that the (single phase) AC connection is run from the charging socket through the KLE and on to the EME, each pulling up to 16A. So my geeky mind would believe that, given special cabling, these two units could be run from a phase each. So connect each charger to its own phase, let the EVSE tell the car to use 32A, and presto, it will use 2x16A. That would be really nice!
One thing I could be concerned about would be the fact that the two chargers would be run on AC that is out of phase. If they shared control electronics, the active rectifying of the AC could go wrong (if the timing is only based on one of the phases). However they do not seem to be connected through other connections than the CAN busses.
Too bad BMW did not give us this option - it could actually be implemented using a few contactors controlled by the LIM (charge control unit). However 2-phase charging probably isn't a standard, even if would probably work perfectly fine with all 3-phase EVSEs.
It could be fun to do a wiring hack, but given warranty issues etc., I don't think I've got the guts for it right now :?
It would be perfect to do multiphase charging, allowing for faster charge times on a 3x16A outlet. So... here's the nerdy and quite theoretical part :ugeek:
I'm an electrical engineer, and as such of course interested in the inner workings of the i3. Looking into the tech docs available in the global i3 facebook group, it seems that 32A / 7.4kW charging is actually handled by two chargers in the i3. One 3.7kW charger in the EME (electrical machine electronics, present in all models), and one 3.7kW charger in the KLE (convenience charger). The KLE seems to have had some problems as from what I can read in this forum, but hopefully they're fixed by now. As I understand the document, not all i3s are fitted with a KLE, but it will be there if the DC option is chosen.
The interesting part is that the (single phase) AC connection is run from the charging socket through the KLE and on to the EME, each pulling up to 16A. So my geeky mind would believe that, given special cabling, these two units could be run from a phase each. So connect each charger to its own phase, let the EVSE tell the car to use 32A, and presto, it will use 2x16A. That would be really nice!
One thing I could be concerned about would be the fact that the two chargers would be run on AC that is out of phase. If they shared control electronics, the active rectifying of the AC could go wrong (if the timing is only based on one of the phases). However they do not seem to be connected through other connections than the CAN busses.
Too bad BMW did not give us this option - it could actually be implemented using a few contactors controlled by the LIM (charge control unit). However 2-phase charging probably isn't a standard, even if would probably work perfectly fine with all 3-phase EVSEs.
It could be fun to do a wiring hack, but given warranty issues etc., I don't think I've got the guts for it right now :?