Voltage question

[KJM]

Hi, while winterizing my boat today I noticed that the voltage showing on the gauge was only 12. Its usually well over 13. Using a volt meter I checked the pos and neg at the altenator and it was in the 15ish range, checked at the battery and got over 13, then checked at one of the solenoids and also got over 13. This was with engine idling, revving up didn't change the reading at the gauge. Meanwhile the engine seemed to work fine and I let it run a good while to make sure it wasn't just running on battery power, I tightened the belt to the altenator a couple of days ago and hadn't run her since, so i'm thinking I might have loosened a wire to the gauge or something? Any ideas would be welcome, but I probably won't be testing any solutions until next spring because I have the engine drained, antifreeze ran thru, oil changed, engine fogged and I'm only doing that once this fall!

 

[bruceb58]

Sounds like you have a voltage drop between the alternator and the battery. Check the condition of the wire at both ends. The one end will likely be down at your starter.

 

[KJM]

Thanks for the reply. Its probably because the battery terminals were pretty rusty and I didn't clean them when taking the reading, I just scratched at the surface with tips of the probes although did also notice that discrepancy. But that probably wouldn't have anything to do with the low gauge reading do you think? Where exactly does the volt gauge in the dash get its reading from?

 

[Pete104]

Why not check the voltage at the gauge? It's good every where else!

 

[NHGuy]

Clean up your electrical contacts before returning to service in the spring. Then recheck The dash is farthest away so it has the most opportunity for voltage drop.

 

[bruceb58]

Why not check the voltage at the gauge? It's good every where else!

Alternator is at 15V..way too high.

 

[KJM]

Re the alt at 15 : It may have been high 14. something. but it did seem a little high to me too. What would cause that? As to checking the voltage at the gauge, I didn't realize you could do that. I thought maybe there was some kind of sensor on the alt or somewhere and then sent a lesser signal to the gauge. Wish I had known that this evening, that would have been an excellent place to check to rule out faulty gauge. I feel kind of dumb for not thinking of that but that's the beauty of this forum, I learn something new everytime I post a question! I also just remembered that my tachometer hasn't been working right all this summer. It goes up to 500 and stops no matter how high I rev past that. I wonder if the two are related, other then the fact that they are 40 yrs old and desperately need to be replaced?

 

[bruceb58]

If the voltage at the battery doesn't measure almost exactly what you measure at the alternator, you have an issue.

 

[KJM]

Ok, I'll save these suggestions and see what I can come up with in the spring. New set of gauges is on the never ending "need to get" list regardless. Man, one day into post boating season and the next year projects are starting already, ya gotta love it!

 

[Pete104]

Alternator is at 15V..way too high.

I guess I missed the "15ish" on the first round.