REX Power direct to Motors?

REX power could be direct to battery or motor depending on the load on the electric motor. Ie. higher speeds REX+Battery power the motor. Lower speeds REX powers the motor and holds charge on the battery?

Any one know if this happens?

The alternative being the REX only ever charges the battery and the EV motor pulls the power back out.

I'd hope the generator can feed the motor direct... This would save using up some of the precious charge/discharge cycles of the cells.

Not sure if there are charge/ discharge terminals or just + and - . ie there's a voltage at the battery terminals - if the EV motor is sucking more than the rex generator provides current will flow out the battery. If its less - current will flow into the battery. I'd hope it's a bit more advanced than that!

All depends on what the box of power electronics between the generator, motor (and regen) and battery does.

Need someone to do a tear down of an i3 and get some meters in there

Hi,

for what it's worth, from BMW's own dealer info documents:

7.5.1. Overview
The optional range extender powers a range extender electrical machine, where current is supplied to the high-voltage intermediate circuit. Depending on requirements the current flows directly to the motor of the electrical machine or to the high-voltage battery unit. The aim is to keep the state of charge (SOC) at a constant level.

Regards, Steven

They not daft are they them electrical engineers.

Just wot I wud a done.

In more detail, the Rex generator outputs 3 phase AC that is converted to high voltage DC by the Range Extender Machine Electronics REME. That DC is then converted back to 3 phase AC to power the main motor by more electronics. So the power generated isn’t directly used by the motor as it goes through two conversion steps that incur some loss. Both those electronic units have coolant supply lines to deal with the heat due generated to inefficiency.