Overheated alternator on 3.0LX

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smassey22180

Petty Officer 1st Class
Joined
Apr 15, 2013
Messages
210
I accidentally drained my battery by leaving the ignition on for a few days. I charged on my trickle charger for 12 hours and that got the battery to 11 volts and I was able to start the boat on muffs this morning (with hopes of going out). I then let the engine run at 1200 RPM for a few minutes to charge the battery. After 10 minutes I saw a little smoke in the (closed) engine compartment and determined it was coming from the alternator. Alternator case was 300 degrees. Belt was 120 so it was not the belt. I assume my little alternator was not able to charge my mostly dead 1000 cca battery.

I let everything cool off and the smoke did not return at idle with engine compartment open for air. Did I do any damage? Can I fully charge the battery and safely go out on the water tomorrow? Also which alternator do i have (pics attached)? Thanks to all for a great active forum!
 

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alldodge

alldodge

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Re: Overheated alternator on 3.0LX

Need to put your battery on a charger which puts out at least 6 amps, a little more is better. A regular leadacid battery which is not a deep cycle type can be damaged when drained below 60%. Put it on a charger for several hours and then load test.

Have you measured the voltage from the yellow wire on the ALT while running? If not start it up and it should be around 14 volts, if not you may have fried the ALT.
 
M

Maclin

Admiral
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May 27, 2007
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6,761
Re: Overheated alternator on 3.0LX

Looks like the large wire got pretty warm and tried to cook the insulation, looking at the part just before it goes into the boot. I bet it is hard and not very pliable. It may have wicked up some corrosion (before this incident) and has some resisitance in it now from that then got overloaded when trying to charge that battery. If that wire is hard and not pliable then it really needs to be replaced.
 
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smassey22180

Petty Officer 1st Class
Joined
Apr 15, 2013
Messages
210
Re: Overheated alternator on 3.0LX

Thanks for the replies. Trickle charger got the battery up to 12.5 volts. Got 14v on the yellow wire with the engine running. The wires all looked good. The iPhone flash made them looks worse in the picture than they were.

First run on the water today and alternator got up to 300 degrees again but did not smoke. We let it cool off and then did one more run as a test before giving up for the day. This time I ran the blower and the alternator only got up to 250. Each run after that the alternator ran cooler as the battery continued to charge. Once the battery was fully charged it ran at 150 degrees. My guess here is a 1000 cca deep cycle battery may be too big for my boat. What generally comes with the 3.0s?

thanks
 
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smassey22180

Petty Officer 1st Class
Joined
Apr 15, 2013
Messages
210
Re: Overheated alternator on 3.0LX

2 batteries would be nice for redundancy but overkill for my boat. I have no electronics. Just a tiny blower and bilge pump. I was not trusting the alternator so I had it tested at a real alternator shop. Everything came back good. The tech said the coating on the winding will smoke if they get hot. Around 300 degrees my by measurements. The diodes can also smoke which is why I wanted to get it tested.

thanks
 
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alorio1

Seaman Apprentice
Joined
Jul 1, 2013
Messages
34
Re: Overheated alternator on 3.0LX

I once got a super sized battery for my truck and it fried my alternator. The alternator shop verified the super sized battery was the cause and would not warranty the work they had done until I put the correct battery in place.
 
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