[dpmike]

Could just be what Brandon says which is normal.
Or it could be deliberate - some cars (used to) drop heavy loads when starting to reduce the battery load, though with modern batteries this isn't so much of an issue. However, with the extra stress of stop/start maybe it's being done again.

 

[dpmike]

Thanks. I figured the starter would just be drawing more energy, but it doesn't happen on any of our cars with LED lamps. Not quite sure why this only happens with halogen-- is it because the LED lamps draw so little energy?

Liam

Not really. LEDs behave differently to filament bulbs in that they don't change their brightness much with a change in voltage. Also in a headlight or drl application they will usually be connected to the 12V supply via electronics which may also even out the supply to them.