Do plug-in hybrids receive any charge from the engine?

C3PO

Driving my mothers plug-in hybrid Merc today and it seems to turn off the engine and switch to electric power at very low speeds. But she never plugs the car in so in order to do this the engine must be giving the batteries some charge? Is that the case?

innrain

Yes. It is called recuperation or regenerative braking and it's the principle used by the so called self-charging hybrids.

https://en.wikipedia.org/wiki/Regenerative_brake

salamiii

Do I need to charge my plug-in hybrid battery?
For optimum performance, it is recommended that you charge your plug-in hybrid on a regular basis - for example overnight. If there is no opportunity to charge the car, you can still remain fully mobile thanks to the combustion engine. Through innovative radar-based technology, the system automatically adjusts the car's regenerative braking to recuperate as much energy as possible, extending the driving range of the battery or charging it. 

zg3409

The engine is used to charge the battery. Most PHEV have options of engine only, battery only, automatic. If you are not slowing down regenerative braking does not charge the battery. It uses power of engine to charge back up battery.

Real world savings of PHEV that is never plugged in are not that high. They inky really save in long stop start daily city driving.

Due to incentives given PHEV are often cheaper than same non PHEV car, so often the non PHEV is not even a purchase option.

irishgrover

if you're (or more specifically your Mother) is not plugging in a PHEV, then you're not using it right. Apart from the economic and environmental benefits, driving a PHEV in EV mode is nicer and quieter than driving the same in engine mode.