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Wuzaboater · 06-05-2020, 04:28 PM

Last trip out the alt. lite came on, and gauge showed a little over 12v. The output at alternator showed zero. Had alternator pulled out, and rebuilt - diodes and one other part were replaced. Re-installed alternator - gauge showed just under 14v - good news. However, 15 minutes into a drive the alternator gauge back to showing a little over 12. Same readings at coach panel, and solar controller. Solar not hooked up, no invertor on. When driving, turning on lites caused drop in meter volts.

Is is possible that my original issue is something that is taking out the alternator ? I suppose its possible that the alternator rebuild was defective, but I suspect something else. Solar keeps batts up easily, batts are relatively new.

Neece Leville stock alternator.

Thanks in advance for any comments, suggestions, and input

Timaz · 06-05-2020, 05:38 PM

I hope this doesn't sound silly, But check the inline fuse on your engine battery. If you are using the factory wiring to your batteries like I am you need to bump that fuse to 30 amp. I have still blown the 30 amp fuse by doing something wrong.

If the fuse is blown, replace it and start your engine.

Tim

YC1 · 06-05-2020, 07:16 PM

That fuse must be for a field wiring and certainly not the charge/output line from the alternator.

I don't know if you have an internal voltage regulator or an external one. The person that rebuilt it would have known.

A rebuilt could die just because it was an old alternator to start, the person made a mistake, or the new parts died.

Been in electronics half a century and new parts fail. Embarrassing to the technician and company when this happens.

If the fuse is blowing it could be the fact that the batteries are really low and need to come up a bit before the alternator can handle the load. Alternators are NOT battery chargers as such. They are battery refillers. They are designed to refill batteries after starting and to keep up with light loads such as headlights etc.

If that fuse mentioned is blowing I would install a self resetting breaker. About $5. It will cycle on and off as the load diminishes.

Run you generator and onboard charger to get the batteries at a level the alternator can handle.

Wuzaboater · 06-06-2020, 07:00 AM

I believe the Neece Leville is internally regulated but will confirm. Batts maintained well on solar. Thank you for the tips - I will investegate further and advise. My biggest concern was that something external was causing the alternator failure.

Cj D · 06-06-2020, 07:20 AM

Yes, the LN alternators are self regulating, so even if overloaded, you should get much longer life than 15 minutes. It has to be a part missed in the rebuild. For example, the regulator may only act up when hot, but one of the diodes was bad...so the tech left the regulator and changed the diodes. Now, with full power the regulator finally gave it's death rattle for good.

Still, most reputable shops will warranty the rebuild for a year.

Wuzaboater · 06-11-2020, 02:16 PM

Before we took the rebuilt alternator out we did some testing, and discovered the fuse in batt compartment marked 'DVAC' was good, but loose. Re-inserted the fuse and the alternator began working properly. All appears to be well now. We actually got the tip to check the DVAC circuit from the shop that did the rebuild. Hope this might help someone else down the road.

Cheers