Lights Dimming

Just wondering if anyone has had this same problem or if someone could tell me Battery or Alternator?

When idling using the power windows causes the lights to dim quite a bit and the window is very slow, but when I rev the engine or accelerate just a bit the it is fine and the lights dont dim at all.

Thanx far any help.

You don't say what year or how old your battery is. It sounds like the battery is dying and won't take a charge. When you rev the motor a little the alternator output picks up and handles the window electrical load. All that said though, electrical problems can be a combination instead of just a single point failure. I see a possilbe mix here of battery failure and diode failure, BUT I would start by testing the battery and if the voltage or specific gravity is low and it is over 2.5-3 yrs old, replace it.

Shoot sorry,

2000 K1500 Burb, bought it used and it looks like the original battery so prob about 3 years old.

OK, I bought a new battery (I wanted more CCA anyway) and still the same thing, when I use the elec. windows they go down fine but when bringing them up the window slows and the lights dim?? I would like to avoid the dealer and try to do it myself, any help would be much appreciated.

when your alternator is putting out the correct voltage, it runs at 14.4 volts. your batter runs at an even 12. maybe somethings up with the voltage regulator in the alternator, causing it to not put out the full 14.4 volts at idle. that would explain why things seem to dim. i would have NAPA test your alternator, and make sure its putting out what it should. it may just be the way it is. i know my burb can barely keep up if i have the A/C on, both blowers on, and the radio, then i try to put a window down at a steady 2500 rpm, mine still bogs down.

hope this helps...

rob