Engine speed drop when using electrics
Just wondering if this is normal or anything to worry about as I have never noticed it in any other car I've had.
Basically the easiest way to observe it is if the enginee is idling, stays about 900 rpm, if I then pull up the windows the engine speed drops to about 750-800, hear it start to struggle the the speed goes back up to about 1200 rpm, then drops down to 900. This happens if I do windscreen wipers or anythign really just not as noticeable.
Probably nothing to worry about but why does this happen, surely the engine could just stay at a constant speed of 900rpm (like it would in any other car I've had), the battery voltages are fine although you can also see the needle drop slightly when you do this as well before going back up.