Voltage Question

[C17LoadSmasher]

I have a 2001 Mercruiser 3.0L with a Alpha 1 Gen 2 outdrive. I took the boat out today, and the voltmeter is indicating slightly below 13V while the engine (and alternator of course) is running. I believe it should be higher, usually around 14-16V while running. What could cause this, or is it normal? Everything was 10-4 the last time I had it out (two weeks ago).

 

[Dunaruna]

Re: Voltage Question

Alternator could be faulty (not charging) the battery will still have good voltage until it runs down from starting & accessories. Check voltage at alternator not the battery - this will tell you if your wiring or connections are o/k. The voltage gauge is usually quite a distance from the battery and its not unusal to get a 1 - 2 volt drop in that distance. In other words your alt could read 14v but your gauge 13v.<br />Happy boating

 

[C17LoadSmasher]

Re: Voltage Question

Well I went and pulled the instrument panel and got my trusty voltmeter to see what it read at the panel. It appears to be the actual gauge itself. I get 11.4-11.7 VDC with key on, and with engine on, 13.7+. Is this a good measurement? I didn't check it at the alternator, it started to rain, so I put the boat away. I am going to the dealer on Monday or Tuesday, and will see about a gauge replacement (my understanding is that the gauges themselves have their own mfr warranty).

 

[Trent]

Re: Voltage Question

Easy check... Just check at the battery. With engine off and key off check battery voltage. Then crank engine and re-check. But make sure you rev the engine to 1500-2000 rpm first. Why? The "come in speed" of the alternator is somewhere in that range. Now if the voltage goes up then the alternator is charging. Should be 13-14.5 volts. Now look at the gage in the instrument panel. Does it also go up before and after the test?

 

[akriverrat]

Re: Voltage Question

and if you get good readings at battery it is usually corroded connections between it and gauge.