Bad alternator?????HELP

[derekpfeiffer]

So here's the deal....I had my boat out running on the trailer this afternoon and noticed the volt guage was only going to 12v. So I break out my voltmeter and check the voltage across the batter at 11.96v. then check from the alternator to the battery ground...the same...So I'm guessing my alternator is bad. My question is how much difference is there between a marine and regular alternator?? Could this be anything else??? and also I was wanting to go to the river tomorrow and was thinking that maybe I could just run with that battery and get a spare incase I have any problems with it....b/c i'm just planning on running up the river a ways and shutting it off then just firing it back up at the dock to load it???

Any help is appreciated

Thanks,
Doogie

 

[PINESOL]

Re: Bad alternator?????HELP

first thing first ... use a marine alt ... you may even be able to find someone to rebuild the one you have ... do not use an automotive alternator in your boat ... for safety reasons ... 1 spark from an auto alt + some gas fumes =
big boom ... end result may be allot of fish floating to the top however you wont be in any shape to catch em ..

 

[wire2]

Re: Bad alternator?????HELP

Does the voltage stay the same with the engine running or stopped? If so, the alternator is not producing. A working alternator will also warm up after a few minutes from the current in the windings.

If it's a 3 wire unit, see if there's 12 volts on the 2 field wires. If not that explains the lack of output. On a 1 wire unit it's a bit harder to diagnose.

Is the belt tight? A working alternator can draw several horsepower of energy through the V belt.

 

[Bondo]

Re: Bad alternator?????HELP

Ayuh,........

Just a general Check Over of all the Wiring is the 1st step in seeing if the Alternator needs fixing....

It might only cost a $.30 wire end,..... Instead of a $150. Alternator......

Some Alternators need to see elevated rpms before they light up too.........

 

[derekpfeiffer]

Re: Bad alternator?????HELP

I looked at the ends and they appeared to be good....I had checked it after letting it run for probably at least 5 mins. Took it off idle...prob about 1000-1200RPM. It actually looses about .2-.3 volts when its idling as opposed to the voltage across the battery while it's off. As far as the number of wires it is....I guess I didn't look that close I just pulled back the rubber boot and checked the big wire there. Worse case cenerio is it OK to just take an extra battery and run it anyway. Run up the river and if i have problems just shut it off and float down to the dock and use the new battery to fire up and load the boat??? I just really want to get it out and see how everything else runs.

Thanks for all your help guys...this is by far the BEST thing i've ever found on the internet

Thanks,
Doogie

 

[Bondo]

Re: Bad alternator?????HELP

Worse case cenerio is it OK to just take an extra battery and run it anyway. Run up the river and if i have problems just shut it off and float down to the dock and use the new battery to fire up and load the boat??? I just really want to get it out and see how everything else runs.

Ayuh,...... While I can't say the You Should,........

I Would............

 

[derekpfeiffer]

Re: Bad alternator?????HELP

Right on...i'm telling you I love this boating thing...can't wait till I get confident and really comfortable with all the different things on these boats.

THANKS FOR ALL OF YOUR HELP
Doogie

 

[Coors]

Re: Bad alternator?????HELP

Take it to Autozone, etc, have a load test done

 

[derekpfeiffer]

Re: Bad alternator?????HELP

Yeah i've been thinking about doing that but the last time I had one tested that I was quite sure was bad they said it was good...then took it to another discount autoparts dealer and they too said it was good..put it back on and looked and looked....couldn't find the problem...after running all kinds of jumper wires and test leads...finally decided to put on another alt. and problem went away...so needless to say I lost a lot of faith in their ability to test alternators...but i'll prob. take it in and have it tested in the morn.

Thanks guys,
Doogie

 

[Haut Medoc]

Re: Bad alternator?????HELP

Yeah i've been thinking about doing that but the last time I had one tested that I was quite sure was bad they said it was good...then took it to another discount autoparts dealer and they too said it was good..put it back on and looked and looked....couldn't find the problem...after running all kinds of jumper wires and test leads...finally decided to put on another alt. and problem went away...so needless to say I lost a lot of faith in their ability to test alternators...but i'll prob. take it in and have it tested in the morn.

Thanks guys,
Doogie

I had a problem with an alternator on an 89 Accord.....
Turns out the post where the large wire goes had a ticklish contact internally.....
The people that test it put a clip on there & plug in the appropriate plug, but have to put down the protective cover to run the machine, so it would test out good.....
But when you installed it & it got some vibration it would stop charging....
I figured it out after I put pressure on that post with a hammer handle & you could hear it work, then the vibration would make it cut out.....
Point is, if you can wiggle test the alternator connections while running, you might get results.....

 

[HT32BSX115]

Re: Bad alternator?????HELP

Be careful though......

I had to replace the ALT on my 94 Suburban a couple years ago. I happened to be watching the volt meter on the way home and noticed it drop to about 11v or so about 4 or 5 miles from home.

When I got in the driveway, and opened the hood the ALT was so hot that I couldn't touch it and it was stinking and smoking.

 

[Coors]

Re: Bad alternator?????HELP

Yep, shoddy anymore; wife's mustang alternator recently gave me the-sizzling hot.
Replace and good to go. It was in and out charging, until the interior wiring evidently grounded out, for good.

 

[wire2]

Re: Bad alternator?????HELP

....It actually loses about .2-.3 volts when its idling as opposed to the voltage across the battery while it's off. ....

That's from supplying power to the coil for ignition. The alternator is doing squat.

 

[BAYLINER185]

Re: Bad alternator?????HELP

difference is there between a marine and regular alternator??
------------------------------------------------------------------quote--

The differance is the marine is USCG Approved for boats. They are more sealed and have I beleive spark arrestors inside them to contain any archs that can ignite fuel vapor or fumes. There not just automotive units painted black

I think one of the best places to get a new one is right here at IBOATS. I had to replace one 10 years ago and found them priced from 200 to 400 bucks. My machanic got me one for around 150.00 I think it was and I thought that was pretty good. I see OEM units here for very reasonable prices.

 

[Coors]

Re: Bad alternator?????HELP

Local alternator/starter shop can rebuilt for $125

 

[Gary H NC]

Re: Bad alternator?????HELP

A new one at Ebasicpower is between 100 and 150 bucks..

 

[derekpfeiffer]

Re: Bad alternator?????HELP

I took it out and ran it today and once i got out on the water it started to charge perfect. I cleaned all the battery terminals and all the wires on the alt. too so that might have been part of the problem...So I have an extra battery now just incase. I'll just keep a close eye on it. Thanks everyone for all of your help.

thanks again,
Doogie