ADUK Archive

jont wrote:

PeterE wrote:And does anyone know if the engine still switches off if the aircon compressor is operating, as surely that would flatten the battery in short order?

Usually the compressor is driven off the crank (via a belt/pulleys) in the same way as the alternator, so if the engine isn't turning, the air-con compressor won't be either. More interesting will be in winter when you've got headlights, demisters etc etc. You would hope with the modern electronics in cars they can monitor battery voltage/drain and restart the engine before it gets too flat to crank properly.

ScoobyChris wrote:The BMW's also have "regenerative braking" too which may go some way to helping.

jont wrote:

PeterE wrote:And does anyone know if the engine still switches off if the aircon compressor is operating, as surely that would flatten the battery in short order?

Usually the compressor is driven off the crank (via a belt/pulleys) in the same way as the alternator, so if the engine isn't turning, the air-con compressor won't be either. More interesting will be in winter when you've got headlights, demisters etc etc. You would hope with the modern electronics in cars they can monitor battery voltage/drain and restart the engine before it gets too flat to crank properly.