Engine Voltages Read Differently

PotatoAddict

Cadet
Joined
Mar 9, 2012
Messages
12
Started both engines. Both voltages read 12.5 volts. Raised both engines' RPMs. Port voltage goes up, but the starboard goes down. Do engines use battery power when they run?
 

Technorunner

Petty Officer 3rd Class
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Oct 1, 2010
Messages
95
Re: Engine Voltages Read Differently

Gasoline engine uses a little batterypower. Depending if you got electricfuelpump or not. Items that takes power are ignition coil, fuelpump ( if electric) and the sensors. But that is so little power so you shoulden?t notice it in voltagedrop. Might be starboard alternator is going bad and start drawing power from the port engines alternator. Do both alternators go to the same battery. Or do you have one battery for each engine??
 

PotatoAddict

Cadet
Joined
Mar 9, 2012
Messages
12
Re: Engine Voltages Read Differently

Gasoline engine uses a little batterypower. Depending if you got electricfuelpump or not. Items that takes power are ignition coil, fuelpump ( if electric) and the sensors. But that is so little power so you shoulden?t notice it in voltagedrop. Might be starboard alternator is going bad and start drawing power from the port engines alternator. Do both alternators go to the same battery. Or do you have one battery for each engine??

One battery bank for each engine. I can combine them all together with a switch but I wasn't using it at the time. Thanks.
 

Bondo

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Apr 17, 2002
Messages
70,465
Re: Engine Voltages Read Differently

One battery bank for each engine. I can combine them all together with a switch but I wasn't using it at the time. Thanks.

Ayuh,.... I'd guess the motor with the low voltage needs an alternator...
 
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