need help with alternator

Joined
Nov 6, 2011
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50
ok so I need help. I but my battery in backwards on mistake. but quickly noticed and corrected. looked everything over nothing seemed damaged till my boat died on the next water test. so I checked the volts at battery and it read 10v so I got back home charged the battery and ran the boat on muffs. I checked the volts when it was running and it read 12.4 but I know it should read somewhere in the 14v range. so I believe my alternator is toast. only problem is I cant find my alternator online new anywhere. what should I do. the numbers on my alternator are 1100721 32a.
 

Bondo

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Re: need help with alternator

ok so I need help. I but my battery in backwards on mistake. but quickly noticed and corrected. looked everything over nothing seemed damaged till my boat died on the next water test. so I checked the volts at battery and it read 10v so I got back home charged the battery and ran the boat on muffs. I checked the volts when it was running and it read 12.4 but I know it should read somewhere in the 14v range. so I believe my alternator is toast. only problem is I cant find my alternator online new anywhere. what should I do. the numbers on my alternator are 1100721 32a.

Ayuh,.... Welcome Aboard,.... What motor is this alternator bolted too,..??

What drive is behind that motor,..??

'bout what Year is All of it,..??
 
Joined
Mar 27, 2010
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Re: need help with alternator

Ayuh,.... Welcome Aboard,.... What motor is this alternator bolted too,..??

What drive is behind that motor,..??

'bout what Year is All of it,..??

Come one.... I thought you were good!! lol ;)

yeah man, we're gonna need a little more help on this one to get to the next step...... stay tuned......
 

Bt Doctur

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Aug 29, 2004
Messages
19,093
Re: need help with alternator

My guess is i dont know what it is.
 
Joined
Nov 6, 2011
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Re: need help with alternator

also note that for some reason the other day the drive didn't go down when I pressed the button so I went in got a beer and tried again and boom it worked again that was the first time that ever happened. I can take pics of the motor and outdrive if someone can tell me how to post them
 

Bt Doctur

Supreme Mariner
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Aug 29, 2004
Messages
19,093
Re: need help with alternator

how many wires are on the alt . 2 orange and black= GM 1 wire, 4 wires orange,black, small red, small purple(black) =GM 3 wire.
these will be 55A and should be a bolt in.
photobucket works good.
 
Joined
Nov 6, 2011
Messages
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Re: need help with alternator

heres the alternator I just bought off amazon for 65 buck ALTERNATOR 71-84 MERCRUISER STERN DRIVE...
 

Bt Doctur

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Aug 29, 2004
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19,093
Re: need help with alternator

that wiring comes back correct for your year, this has a external voltage regulator ,correct?
there is also a ammeter gauge?
 
Last edited:

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: need help with alternator

the drive is pre alpha

It's not, it's an MC-1...

http://forums.iboats.com/mercruiser...ve-needs-help-go-down-597987.html#post4160821

Your alternator is no longer available from Mercury Marine, (original part# -37615A1, supersedes to part# -47456A1)

It's likely to be a shorted diode or/and a burnt regulator...

I would take the alternator and the regulator to an Auto-eletrician, he may be able to repair it.

Any replacement alternator will have an internal regulator and will be a 'one-wire' unit. That means removing the old regulator and insulating the connections, also the small blue wire that is currently on the existing alternator. Once those wires are isolated, then just put the new alternator in and connect the single large Red/White wire to it...

Chris.......

EDIT: lots of posts while I was researching this one... The alternator you bought from Amazon should work. All you have to do is follow my instructions for removing and isolating the old wiring.
 
Last edited:
Joined
Nov 6, 2011
Messages
50
Re: need help with alternator

yes its got a external regulator. I could take it to a shop and have them repaired but they don't make them no more so I will have to swap it all out eventually so what better time then now. also I work on cars a lot so im doing most the work on my boat to keep cost down as much as possible. I just don't understand how I would wire the alternator or if I even can. but I do need to know right away if the one I bought will work or not so I can cancel my order if it cant.
 
Joined
Nov 6, 2011
Messages
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Re: need help with alternator

I would like to use the one wire set up as well considering my options. and the alternator I bought is 120ams I believe will that be a problem.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: need help with alternator

yes its got a external regulator. I could take it to a shop and have them repaired but they don't make them no more so I will have to swap it all out eventually so what better time then now. also I work on cars a lot so im doing most the work on my boat to keep cost down as much as possible. I just don't understand how I would wire the alternator or if I even can. but I do need to know right away if the one I bought will work or not so I can cancel my order if it cant.

In my previous post I gave all the instructions for converting your current system to the one wire alternator...

I would like to use the one wire set up as well considering my options. and the alternator I bought is 120amps I believe will that be a problem.

The alternator will only produce 120 amps if it's demanded. During normal running the usually demand is about 3-6 amps, and with a fully charged battery, that's all the alternator will produce...

Chris.....
 
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