voltage hand moving in cluster

Hi guys,have an 05 impala with 3.4,she had the base cluster in her and recently i just put an ss cluster with oil,temp,volts and tach,i'm noticing that my volt gauge for the battery is fluctuating back and forth sometimes with the heater,rear defrost on but never goes past half way to the left,with everything off as in rear defrost and heater and i press the power window button it draws the volts hand way down,is this normal for the hand to move like that,also with rear defrost,heater and lights on when i put the brakes on it draws a lot of juice,volts hand goe down a little past half lights in cluster dim a bit and heater slows down till i give her the gas and then everything speeds up and lights brighten up,battery checks out fine and also the altenator,,i tightened the 2 bat cables,once and a while i will here my belt screech but i thought that the belt tensioner would keep it tight all the time,only thing i can think of maybe the belt slips when there is a load on,how ever i do put armorall all over the engine when i shampoo the engine as i am a professional car cleaner and detailor for past 25 years but never had a problem,thanks,mike

Hi guys,have an 05 impala with 3.4,she had the base cluster in her and recently i just put an ss cluster with oil,temp,volts and tach,i'm noticing that my volt gauge for the battery is fluctuating back and forth sometimes with the heater,rear defrost on but never goes past half way to the left,with everything off as in rear defrost and heater and i press the power window button it draws the volts hand way down,is this normal for the hand to move like that,also with rear defrost,heater and lights on when i put the brakes on it draws a lot of juice,volts hand goe down a little past half lights in cluster dim a bit and heater slows down till i give her the gas and then everything speeds up and lights brighten up,battery checks out fine and also the altenator,,i tightened the 2 bat cables,once and a while i will here my belt screech but i thought that the belt tensioner would keep it tight all the time,only thing i can think of maybe the belt slips when there is a load on,how ever i do put armorall all over the engine when i shampoo the engine as i am a professional car cleaner and detailor for past 25 years but never had a problem,thanks,mike

replace belt keep lubes off the belt ...make sure the pulleys are clean, wash with mineral spirits before new belt...is put on...make sure new belt is the correct and exact size,, as the spec...don't believe the part store...

check that the tensioner is working...

belts will slip then the rubber gets glazed then poor grip..

As the heaters cycle on and off, you will get some voltage drop, especially at idle, but it shouldn't be much. I'd change the belt, and see if that helps.

As the heaters cycle on and off, you will get some voltage drop, especially at idle, but it shouldn't be much. I'd change the belt, and see if that helps.yes thanks,i changed the belt today plus the water pump that was leaking spraying antifreeze onto the front of the radiator also was going down on the belt making it slip too,so far so good,thanks