charging system

[rayzcam1]

I have 1989 maxum 2800scr. the problem i'm having is that it charging fine until it reaches 3500 rpm and above the voltage drops to 12 volts until i bring the rpm back down and then voltage goes back up to 14 volts. new alt and batteries,new belt and not slipping.any idea's thanks

[shrew]

Are you reading the voltage from the volt meter at the dash? On the battery, or off the alternator itself??

There is an excitor wire from the battery to the alternator. The alternator won't send charge unless it gets voltage from the battery to begin with. The alternator doesn't typically send a charge to the battery until the engine reaches at around 1,000+ rpm's.

Once the battery is detected as being full some charge controllers will stop sending a charge to prevent cooking the batteries.

Getting a charge above BELOW 3,500 is odd.

My voltmeter on the dash of my 99 2800 used to dump when the fridge turned on.

If you're using the volt meter on the dash, then I'd start by measuring at the battery. Then measure at the alternator.