Possible bad Alternator in a '09 SV211

[Super B]

This weekend I took the boat out on the water and noticed that the volt gauge was reading at 11 volts and would not get any higher when the RPMS increased. After about an hour of run time, the boat began to spit and sputter and would only idle in gear. Then of course the boat stalled due to the batteries were completely drained. This year I did change up my set up by adding a Perko battery switch and I did relocate my two batteries..

So after being towed back to the landing, I took the boat home and charged both batteries, fired up the boat and checked the volt output while the boat was running. I was showing on the voltmeter at the batteries 11.8. So I am assuming that my alternator went south. I did verify that the 50 amp breaker was not tripped.

Any other things that I might be missing?

Thanks.

[Chexi]

Search youtube for testing an alternator. There is a lot of info there. You could just have a loose belt, which would prevent the alternator from spinning. Lots of tests on youtube to isolate the problem.

[dfoster]

I just went through this with my '04 SV (with ZR6). Basically, you need to double-check a bunch of things, but it sounds like the alt went bad.
1. Check the belts... watch the alt when running it should be spinning, etc.
2. Make sure to check the voltage at the battery with the engine off... a full bat should be more like 12.4V, but the dash tends to have a weak ground... so use a multi-meter and measure at the battery. Measure with everything off and each battery isolated (don't have them combined with the dual bat switch). Each one should read about the same.
3. Check the same voltage (engine off) at the alternator post (post vs. engine ground). It should only be different by less than 0.1V. If you have a difference then the issue is in your wiring or switch.
4. Now start the engine while watching one battery. The voltage should drop. Note the voltage and then check at the alt post (I needed to connect a test lead so I could swap back and forth easily). Again the voltage diff when reading at the battery vs. at the alt should be less than 0.1V. Now do the test on the other battery... should be the same. Any difference between the two batteries would point to a battery or wiring issue to check.
5. If both batteries, the switch and the wiring look good, you probably lost the regulator in your alternator. You can pull it out and bring it to an alternator shop and they can test it for you. You can't test it easily on your own other than the above. "Fielding" the alt is dangerous and could blow your electonics, so don't try to test using some of the YouTube methods... they can cause damage.
6. If you have a bunch of black "dust" on the front of the alternator, which is from the belt, this is most likely the issue... the dust gets pulled into the alt and causes the regulator to over heat.

Assuming that it is the alt after you tested, you can either get a new one on NautiqueParts (that's what I did) and replace it... not really hard, or take it to a local shop to have it re-built. Just make sure they understand what a "marine" alternator is... or you might get one that isn't spark-proof and that... would be "bad".

I was told these go bad from time to time... and when it does it is sudden. So, what you describe makes sense based on my experience.

Doug

[georges]

Make sure your battery connections are clean and tight. They can shoot you in the foot!

[Super B]

Thanks for the tips. There is a slight chance that the boat still be under the factory warranty (crossing my fingers). If not, I will follow your instructions.

[ffmedic74]

check the voltage at the alternator, PME box, and at the battery. At the alternator will tell you if the alternator is putting out high voltage or not. The PME box and battery will let you know if you need addtional ground or positive cables or a bad connection.

[Super B]

Good news, the boat is under warranty. It will be heading to the dealer tomorrow. Thanks for the suggestions!