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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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My '80s 115 hp 2 stroke isn't charging the batteries.

Customer Question

my '80s 115 hp 2 stroke isn't charging the batteries.
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.
Hello. My name is ***** ***** have an ohm meter to do some testing? How are you checking the charging out put?
Customer: replied 2 years ago.

Yes I have an ohm meter and know how to use it.

I checked the charging output at the battery terminals. The fully charged bat was at 12.42 v before starting. after starting it dropped to 12.37v.

I started and stopped it several times to put a draw on the bat. It kept dropping and was at 12.3v when I shut the engine off. When out on the lake the bat drops lower and lower.

I have been using a battery charger to recharge at home.

Expert:  Tan replied 2 years ago.
Ok locate the rectifier disconnect all the wires not test from where the yellow wire connect to the red batt terminal. Connect the red lead to the yellow terminal and the black lead to the red terminal. Check the reading then reverse the leads. Check the reading. Do this test on both the yellow terminals. You should get a reading in one direction and none in the other direction. Then test from red terminal to the case of the rec you should get no reading. Post back with findings.
Expert:  Tan replied 2 years ago.
Here is a pic of the rectifier. A & C are the yellow terminals and + is the red batt terminal. If your rectifier looks different the test is the same for all rectifiers.
Customer: replied 2 years ago.

OK...I'm not actually near the boat now. Its up at the lake.

I have printed off the instructions above (There seems to be a typo in the 1st line. Can you clarify that please) and will check the rectifier and get back to you.

Expert:  Tan replied 2 years ago.
Ok lets do it this way the rectifier is what you are testing in this diagram. Test rectifier with wires disconnected. Test from A to B then from B to A what is your reading on each test?Then test from C to B and B to C. What is your reading?Then finally test from B to G. What is your reading? Does this make better sense?
Customer: replied 2 years ago.

that makes sense. I will get back to you later.

Expert:  Tan replied 2 years ago.
Ok great.

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