I have a new alternator with a tight belt...still getting a lot of drop on the voltmeter after turning electrical stuff on. Could it be a bad battery? I wonder this because when you turn the key to ACC, the voltmeter shows about 9-10. Shouldn't it be at 12??

 

Your best place to test would be at the battery with a real voltmemter. The cluster gauge is not always accurate. If indeed the battery is not holding voltage, take it to a local parts store and the can test it for you, for free usually, to confirm your readings. Normally (of the batteries I've had) a battery will hold roughly around 12.25v ± o.6v.

 

Yea, I got the same thing. I know that they make a gauge the way they do cause they don't know where the needle will go. I did the alt, and the battery to. The old was readin fine from a meter, and it held a load during the load test I did at work. She still drops as if she haves a bad battery or something. It mostly happen while taking off from a stop. I started to think that its was the fan cause it was hot wored, but it does with out the fan running or my amp and head unit on. If anybody have a clue of what else can be tried please let me know to....