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Alternator not charging

Old 06-10-2020, 05:52 PM
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Default Alternator not charging

2003 225 Mercury Optimax

i just put a new alternator on the port engine. When you start the motor the volts bounce anywhere from 11.3-12.1. I run a jump cable from the batteries (negative to negative, positive to positive) started the starboard engine, waited for that side to hit 13.9 volts than started the port engine with the new alternator. Both engines perfect volts.

I switched out the port battery with no luck. The only way I can get the port engine right is if I run the jumper wires from the batteries.

How can I get the port alternator to charge by itself?
Old 06-10-2020, 06:13 PM
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Check to see if purple/red wires have 12v in harness going into alternator
Old 06-10-2020, 06:20 PM
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Originally Posted by Eightpter View Post
Check to see if purple/red wires have 12v in harness going into alternator

I checked the back of the alternator where the hot wire (100 amp wire) goes. I get 12.5 - 12.8, but nothing higher.

Are the purple/red wire what clips into the alternator?

Last edited by Tunaman1344; 06-10-2020 at 06:28 PM.
Old 06-10-2020, 06:34 PM
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Yea, should match battery volts. They are sensing/excitation wires for alternator.
Old 06-10-2020, 06:38 PM
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Originally Posted by Eightpter View Post
Yea, should match battery volts. They are sensing/excitation wires for alternator.
Sounds good, thanks 👍

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