To think turning engine off in stationary traffic means you should turn everything else off too?

[merrychristmstoyou]

I'm debating this with DH in the M4 where we've been completely stationary in traffic for about 20 mins. He's turned the engine off, but the headlights, radio and heater are still on. I'm pretty sure that will quickly drain the battery, so he should turn everything off. He's suggested he restarts the engine instead, but apart from being an environmental no-no am I right in thinking it won't keep the battery charged because the wheels have to be moving too?

If the engine is running it will be charging the battery, whether the wheels are going round or not.

Engine needs to be running to charge the battery but the wheels don't need to be moving.

The engine only needs to be running, the car doesn’t need to be moving and tbh unless it’s a pretty old car it shouldn’t be a problem. Mine is 10 years old and has run lights and music longer than that with no dead battery.

He's wrong. You'll drain the battery doing this...

Sorry, misread.

The engine needs to be on.

If completely stationary I would turn the lights off and probably heater (unless really cold). Radio hardly uses any so that should be OK. My car would run down its battery in 20 mins of headlights but it depends on the car. Turning the engine on uses a lot of power so if you turn it back on, leave it on.

We have an Eco setting that will turn the engine off when stationary. Leaves lights/wipers/aircon/radio running. After 15 minutes or so, engine will re-start to charge battery as level has dropped below that which the computer regards as safe.

I’d suggest you just leave it running TBH. The interior will soon get cold without a running engine and the last thing you want is to find everyone moving off and being unable to start the car, you’d be about as popular as a turd in a swimming pool.

This happened to us last Saturday. Day trip to Calais. Waiting in passport queue with engine off but radio on and various phones charging etc. Car refused to start and everyone had to drive round us. 10 minutes later we managed to start it and it spent the night being recharged at home.