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Which alternator should I buy

"My battery charger bit the du

"My battery charger bit the dust and cooked my batteries. When I replaced everything, I screwed up and hooked the battery up backwards. When I turned on the battery switch, a really big smelly cloud of smoke came pouring out of my alternator.

After I switched the polarity, the boat started ok and all of my electronics seem to work, so I think it's just the alternator. Looking at it, the housing is all corroded so I don't feel too bad about having to replace it.

Looking on the Internet, I see that a Mercruiser replacement cost about $225.00. There are a bunch of other sites that sell new replacements for as low as $65.00. Is their that much difference in quality/operation?

The boat is a 1989 5.7L Alpha One with the original Mercruiser engine."
 
As long as it is a marine grad

As long as it is a marine grade altenator and the same amp output ( 55 amps I believe) you are good to go.

You also could bring yours to a auto/truck electrical repair shop and have it rebiult.
 
An alternator rebuild typicall

An alternator rebuild typically costs about $100.00 where the marine Delco 1 wire is about $65.00 brand new if you shop around. Just make sure the foot (where the pivot bolt goes) is the right size. As the alternator is self exciting you will need to "kick" the engine above 1000 rpm to get it to charge. What brand charger fried? I repair those things.
 
"Best to rebuild your old one.

"Best to rebuild your old one. That way everything fits. I doubt you will find a complete marine alternator for less than $220 and dont try using a automotive alternator, they are dangerous on boats and not leagal.
The rebuild shop can tweek the alternator to charge at slow idle.
Rebuild shoud be close to $65."
 
Richard:

My Guest 30 amp &#


Richard:

My Guest 30 amp (10-10-10) lost one channel; can you repair it? It's sealed.
 
"If it is the one I'm thin

"If it is the one I'm thinking of, Model 2631A, it is unfortunately fully potted. Did the charger bite the dust when the batteries were connected backwards? If so contact Guest as the charger supposedly is protected for reverse polarity. It also has overvoltage protection so it shouldn't have fried your batteries. Have you checked the fuse for that one channel?"
 
100 amp alt. will require a wi

100 amp alt. will require a wire change for the output. My guess is at least 4ga. or 6 ga. multi-strand. The finer the strands the better the current flow.

I would buy one if it would fit my 262 ci 4.3L. It would allow me to charge 3 batteries under way.

Many dealers unload stock in Dec & Jan. I've got some bargains in the winter.
 
"Richard:

The fuse is good.


"Richard:

The fuse is good. Charger's #3 channel output was only 1.25 vdc on that channel. It is fully potted. The 3 yr old battery would not charge so I checked it and found it had a dead cell. Maybe the battery killed the charger. But, the start battery was also dead and the charger channel #1 is good."
 
"Hi Guy,

I just realiz


"Hi Guy,

I just realized that your charger is a different issue from Tims. (It's a Monday.) One bad cell typically means the charger should just stay on. Is your alternator okay? The start battery could discharge through a shorted diode in the alternator and you may not be aware of it happening if no charger was connected."
 
"Richard:

Thanks for the in


"Richard:

Thanks for the info. The alternator was new 2 yrs ago and still has good output. All has been working fine since I replaced the 3 batteries, disconnected the dead charger channel and added a separate charger for the start battery."
 
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