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Old 12-30-2005, 04:49 PM   #1
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Alternator output jumping

Hey Folks,
the output on my 79 Excella keeps jumping. When I start it, it's OK, but after running for a while, it starts jumping up to 17 volts... the lights flicker, and the fuse to the dash blows. Any thoughts?

Thanks, Sebastian
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Old 12-30-2005, 05:43 PM   #2
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1993 21' Sovereign
Colfax , North Carolina
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Sounds like either the alternator is about to take the big crappolla, or you have an intermittent connection. You can take your MoHo to your favorite garage, and ask them to check the alternator.
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Old 12-30-2005, 07:27 PM   #3
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It sounds like the voltage regulator section of your alternator is bad or well on the way. That is what controls the output voltage of your alternator. Also, the rectifier diodes might need to be replaced if they are a separate component and not integrated into the alternator. Any good garage or even a reputable tire center can usually tell by connecting a nifty little gizmo to your battery that checks your alternator output,

Also, if you get a new alternator, be ready for a new battery as well, 'cause 17 volts will fry most lead-acid types.
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Old 12-30-2005, 09:57 PM   #4
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If it is not a bad connection (most likely not) cut your losses and replace the alternator and regulator. Cheaper in the longrun. End ‘O’ problem.
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Old 12-31-2005, 04:04 PM   #5
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1966 26' Overlander
Woodstock , Georgia
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I highly recommend a higher amp rated alternator if you do replace yours. If it is a stock alt its probably 60-70 amps, and a 135 will slide right in and do a better job overall for you. I replaced mine with one from, and used their solid cased aluminum heat resistant starter. I have been very satisfied with both items for quite some time.
I would agree that unless you have a loose connection, your voltage reg is shot, and you should replace the alt at the same time.
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Old 01-01-2006, 08:10 AM   #6
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1985 34.5' Airstream 345
Marietta , Georgia
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I would start with the voltage regulator, it is the cheapest and easiest part to replace, if I remember correctly cost less than $20 and you can replace it in about ten minutes. I also agree with Alan about using a higher amp alternator.
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Old 01-02-2006, 04:58 PM   #7
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1986 34.5' Airstream 345
Louisville , Kentucky
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I agree on checking/replacing the regulator first. It's bolted to the top of the radiator housing. If that's not it then consider removing the alternator and taking it to AutoZone (or similar) as most of these places will test alternators for free. If you need a new one then you're already there.

Like Alan and I also run a higher amp alternator on our 345. It comes in handy then the kids are playing PS2 on the TV and I want to use the inverter instead of firing up the generator.
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