Voltage gauge bouncing low when revving motor?

keysohana

Member
Sep 12, 2019
58
Boat Info
1995 Sundancer 330 DA
Engines
7.4 Carb V drives
So both of my voltage gauges on helm show fine when idle or off, but when I start revving the motors, the voltage gauges start bouncing low...
This is happening to both of the motor gauges..
1995 Sundancer 330DA with Carb Mercruiser 7.4l
Thanks!
 
If there Mando alt they sometimes have an armature go open at high rpm`s 6 inch crank and 3 inch alt is double the rpm
 
Hi, not sure what that means "If there Mando"? but I did check the voltage with motors off and running, when running, they are charging the batteries (13+ volts) 12.8 at rest
 
When did you change batteries last?
A bad battery will make several other parts suspect.
 
So your DVM reads steady while the gauges bounce? Mando is a type of alternator and Merc usually lists 2 kinds per application, 1 being the Mando.
 
mine does that... I than went to the cabin and read it at the panel and it was 13 the whole time

btw welcome abaord theres a whole 330 tread
 

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