lights during idling

[cornacum]

Hi all

I realized that my car's interior lights and head lights brighten up when I push the accelerator pedal while the car is stationary and idling? The lights then dim down again when revs drop down to idle.

Is this normal, or should I be looking into this?

Thanks

 

[DaveT70]

Slight change is normal between running and idle.

A large drop means either the battery is on the way out or the alternator

[isetta]

Normal and quite handy as it helps check your alternator works. If lights go brighter when you raise it above tickover it proves your alternator is pushing out a higher voltage than the battery does. 

[isetta]

But if someone has a car where the lights don’t go brighter it does not necessarily mean that alternator is not working. On some modern cars the alternators have such high output they can give a high output even at tickover speed. 

[cornacum]

Ok, hope it is fine as is.

Thank you both

[RMurphy195]

Normal on most cars I've ever had, up until my 2020 focus, goodness knpws why but I bet someone has an answer ..