Downhill with range extender active

[RJSATLBA]

I wonder how the energy management will deal with long downhill sections when battery capacity has fallen below the level at which the engine runs automatically?

If the slope is sufficient for the car to gain speed without power but the accelerator is set to maintain speed regenerative braking would normally be recovering energy. What happens in this situation when the REx is active because the state of charge is already being more than maintained without the REx, does it cut out or does it run on a zero load, wasting fuel.

This isn't a hypothetical question because my normal drive home ends with a descent of about a mile.

 

[TomMoloughney]

I wonder how the energy management will deal with long downhill sections when battery capacity has fallen below the level at which the engine runs automatically?

If the slope is sufficient for the car to gain speed without power but the accelerator is set to maintain speed regenerative braking would normally be recovering energy. What happens in this situation when the REx is active because the state of charge is already being more than maintained without the REx, does it cut out or does it run on a zero load, wasting fuel.

This isn't a hypothetical question because my normal drive home ends with a descent of about a mile.

The REX will continue to run until the car's state of charge reaches the cut-out threshold at which time the REx will turn off. Here in the US the cut out is 6% SOC (regulatory issues) but in the UK I believe it's 18%. However you should also be able to manually turn off the REx if you want to so your not wasting fuel in circumstances where you know you'll make your destination without it charging the battery any more.