Originally Posted by Azure Fields
Anyone ever run into your interior lights, radio and climate, dimming when you apply the brakes?
Your car is going to need to draw more power when you brake (tail-light, abs, ect.), so some power draw would be expected, but I'm not sure how bad it is for you.
1. Check if you have bad ground (Loose battery cables possibly?)
2. Check your battery output (Should be putting out 12 volts.)
3. Is your alternator getting old (check the alternator output, should be about 13.5-14 volts).
4. Try cleaning your battery terminals.