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Dominick
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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Im having problems with my Mercury 300XS it is running straight

Customer Question

Im having problems with my Mercury 300XS it is running straight off the battery, I have installed two new alternators and it gives me the same problem
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.
Hello, my name is***** you for allowing me to assist you today.
Do you have a multimeter to test the system?
Customer: replied 1 year ago.
Yes
Expert:  Charles replied 1 year ago.
Great,
Test the voltage on the red post on the right side. Then move to the post on the alternator. Is that reading the same?
Customer: replied 1 year ago.
Yesit is the same
Customer: replied 1 year ago.
I have checked just about everything and I'm getting a volt of 12.50 with engine running and 12.30 when I start engine
Expert:  Charles replied 1 year ago.
So how are you determining that it is the Alt that is bad?
Customer: replied 1 year ago.
I changed it because I thought it was bad but the new one is doing the same. Can never get more than battery voltage out of system
Expert:  Charles replied 1 year ago.
Have you had the battery load tested?
How do you know what the voltage is when running? SmartCraft?
Customer: replied 1 year ago.
The batteries are new and the boat is in the water and I tested it while boat was cranked!!! It runs but it doesn't charge the batteries to keep it going
Expert:  Charles replied 1 year ago.
Are there two batteries?
What are the CCA of them?
What type of boat do you have?
Customer: replied 1 year ago.
Yes two batteries, 950 CCA per battery, 23 ft aluminum flat boat
Expert:  Charles replied 1 year ago.
Your batteries are wired in parallel correct? With the positive and the grounds connected on each battery?
What is the voltage at the batteries when the engine is running?
How many pumps and depth finders are in the boat?
do the batteries last for part of the day and then go dead?

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