Dead Alternator?

[izaver]

Hello All,
Was out boating this weekend and had the battery die on me in the middle of the lake. Just clicking noise, not even cranking...
When I got back home, I measured the voltage on the battery with no load -- it was 12.2V.
Charged it up (12.7V) and plugged it back in. Was able to start on ear muffs. Measured the voltage with engine at ~ 1500-2000 RPM -- was 12.5V at battery terminals and at alternator output. With blower and lights on -- was 12.3V at both locations.
Took the alternator to advanceauto and autozone -- none of them were able to connect it. Said they need to know the automotive p/n so they can come up with the right connector.
So, does it sound like a dead alternator or something else may be wrong?
It's Mando 55Amp p/n 155603 alternator. Engine is Mercruiser IO 3.0L Alpha One p/n 0L013754
One more thing though. About a month ago we took the boat on the lake after it's been sitting for over a year. Few minutes after we were cruising, I smelled burnt wiring, stopped the engine and opened the motor cover. There was some smoke coming out of the alternator. Waited a minute and restarted OK with no smoke or smell. Since then, we've been at the lake at least 5 more times. Thought maybe something got into alternator and burnt out...
Any suggestions are greatly appreciated.

 

[BaileysBoat]

Re: Dead Alternator?

Sounds like a bad alternator. Should be 13.5-14.5 depending on the load.
You probably smoked the alternator on that first cruise.
Alternators are designed to maintain a charged battery, not charge a dead battery.

 

[triumphrick]

Re: Dead Alternator?

I agree with Bailey...shows you how little draw that motor is on your system to allow several restarts. Also, one of the reasons for on board plug in chargers is to maintain a suitable level of voltage in your batteries so the alternator isnt overworked. Seems like it did just that tho...

 

[izaver]

Re: Dead Alternator?

Also, one of the reasons for on board plug in chargers is to maintain a suitable level of voltage in your batteries so the alternator isnt overworked. Seems like it did just that tho...

Could you, please provide a link to any plug in charger that can be used for this purpose, so I can study this a bit more. Sounds like a good insurance to have on board.

Thanks for your help.

 

[izaver]

Re: Dead Alternator?

Just realized.... Voltage gage shows 14V when motor is OFF or the battery is disconnected. When engine is ON, the gage goes to maximum limit (over 18V). Is the gage bad too? Could it cause alternator failure or vise versa?
Please, help!
Thanks

 

[Splat]

Re: Dead Alternator?

Sounds like the rectifier in the alternator is bad, Or the voltage regulator.

Can you put a real multimeter on it and see what it reads?

Bill

 

[Boatist]

Re: Dead Alternator?

Alternator can be repaired and usually at very low cost if you can do the work.
Things that fail are the brushes for the slip rings for under $5.
The Voltage regulator for about $15.
The diode block for about $25.
Some have a diode triode for about $10.

I do not know about your engine manual but mine has detailed steps of how to disasymbol and test to find the bad part.
Internal parts are usually the same as auto parts.
The Case and covers are different and have screens to prevent sparks from causing an explosion.

To start with you need the book for your exact motor.

You may want to go to the I/O fourm and see if Don or someone else who knows Merc and tell you which manual you need. Also ask if that manual has alternator troubleshooting and repair.

My OMC Motor manual cover troubleshooting and repair in great detail.

Problem may also not be in the alternator. If your alternator has 3 wires going to it then it could be an external regulator.
If it has a single wire then all the Parts are internal to the Alternator.

I do not know about your town but out here there are about 3 shops in town where they will fix for you or you can buy parts. Some common parts you can get at auto shops like napa.

Besides fixing the alternator you should see if you can find the cause of the failure.
Things that will cause a alternator to burn it self up.
Loose or crroded battery cable, if the battery cable come loose with the engine running it will blow the voltage regulator or the diode block in under 1 second. This also goes for battery switches if turned thru off with and motor running. Some switches just turning them with the motor running will destroy the alternator.

Of course the output wire shorting or comming loose will also detroy the Alternator.

Good Luck.

 

[izaver]

Re: Dead Alternator?

Boatist, thank you for the great info. I called marine elecrical repair shop and they quoted $145 to rebuild and the same price for the new one. fleebay has those for $100 shipped.
I have the manual with detailed troubleshooting procedures, so I'll try and see how far I can go with that, obviously worth a try.
Thanks again.

 

[triumphrick]

Re: Dead Alternator?

Greetings izaver...here's a couple links to some helpful items...
including on board battery chargers. Good luck. Rick

http://www.iboats.com/12_Volt_Bible...25228409--**********.616400262--view_id.11202

http://www.iboats.com/MK210_2_Bank_10Amp/dm/*******.448511819--**********.616400262--view_id.166322