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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14469
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have a 2004 Mercury Optimax 150hp. About three weeks ago I

Customer Question

I have a 2004 Mercury Optimax 150hp. About three weeks ago I hooked up my jumper battery to the battery cables to raise the motor because I had not yet installed my batteries yet. When the motor went down instead of up I realized I had the polarity backwards.( never did this before) when I went out on my first trip I realized the alternator was not charging the batteries and the engine alarm would go off when I tried to trim the motor. Went back to the marina, mechanic chance out alternator and cable with the 100amp fuse. Motor ran about 5 minutes and the alternator burned out. Replaced the alternator and cable again. Worked great for two fishing trips. On the third I went to start the engine and I heard a popping noise at the engine and it did not turn over. Realized that the shift/throttle lever was pushed forward a little and was not in neutral, pulled it back and then was able to start the engine but realized my voltage meter was now reading 12v and not the normal 14.5 when the engine is running. Now the alternator and cable is burned out again. Something else must be wrong and the mechanic can't seem to find it. I am already up to 900.00 for this dumb mistake I made. Any ideas I can give to the mechanic who has worked on outboards for 20 years and went to school for it but is not merc certified??
Submitted: 8 months ago.
Category: Boat
Expert:  Jason replied 8 months ago.

Hello my name is ***** ***** am I speaking with?

How man batteries are currently hooked up to the engine?

Customer: replied 8 months ago.
Two new batteries, they were not in the boat when I used my jumper batter so they are fine.
Expert:  Jason replied 8 months ago.

Is there any kind of battery switch, charging relay, or isolator installed into the boat, or are they just 2 batteries wired in parallel?

Customer: replied 8 months ago.
Battery switch that allows you to use battery 1 , 2 or both. I am currently home and not at the boat but looking for info I can relay to the mechanic.
Expert:  Jason replied 8 months ago.

The battery switch needs to be tested for voltage drop, as well as the battery cables, if there is to much voltage drop across the switch or cables that will cause the alternator to over charge. What your mechanic needs to do is perform a voltage drop test between the battery and alternator. Voltage drop is caused by resistance in an electrical circuit that is not supposed to be there. This resistance turns into heat (like a light bulb) and makes the alternator work that much more harder to try and charge the battery. It will do it for a while, but it will eventually burn up.

The batteries themselves should also be inspected for a dead cell. If there is a dead cell in either battery that will cause the alternator to overcharge and then burn up as well.

Does that make sense to you?

Customer: replied 8 months ago.
The mechanic did replace the harness between the alternator and the batteries. What would cause the alternator to burn out along with the 100 amp fuse just as I turned the key to start it?
Expert:  Jason replied 8 months ago.

The mechanic did replace the harness between the alternator and the batteries. What would cause the alternator to burn out along with the 100 amp fuse just as I turned the key to start it?

If the harness was installed correctly then no, it wouldn't cause it.

Was there anything else?

Expert:  Jason replied 8 months ago.

I think that should do it. But I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you

Jason

Customer: replied 8 months ago.
Nothing else replaced but something is causing these alternators to burn up.
Expert:  Jason replied 8 months ago.

I understand. Did you read my reply about voltage drop testing all of the cables and switches, as well as checking the batteries for dead cell?

Customer: replied 8 months ago.
I will relay that info to the mechanic and let you know. Thanks
Expert:  Jason replied 8 months ago.

You are very welcome. Please let me know if you have any troubles when trying to select a rating for my service.

Good luck!

Jason

Expert:  Jason replied 8 months ago.

It looks like you read my answer without replying back or leaving a rating for my service. Please keep in mind the website does charge you to speak with me. But they will hold your money and not credit me for helping you until you select a rating for me. If you have a further question on the issue by all means feel free to ask. If not, kindly select a rating for my service.

Thanks again,

Jason

Expert:  Jason replied 8 months ago.

Hello. Just checking in. You have not put through a rating for me yet, did you have any other questions on the issue?

-Jason

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