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Jeremy R.
Jeremy R., MarineTechnician
Category: Boat
Satisfied Customers: 9020
Experience:  Multiple factory certifications 20+ years of experience.
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I have a 2001 Yamaha HPDI 150 model number Z150TXRZ. The engine

Customer Question

I have a 2001 Yamaha HPDI 150 model number Z150TXRZ. The engine is does not appear to be charging at low speeds Battery voltage is 12.2 and at idle it is 12.4. I cleaned all the connections and still no change. I tested the output of the stator windings by the green wires one at time. Cranking I got 1.6 volts on a DVM and at 1500 RPM the reading was 6.45. At 1500RPM the voltage goes up to 13.0. Do I have a problem?
Submitted: 2 years ago.
Category: Boat
Expert:  Jeremy R. replied 2 years ago.
Hi, My name is***** you for letting me try and assist you with your question.
You don't have a problem.
The engine uses a good amount of power to run so still producing more than battery voltage at idle is proof it's charging or at least trying to.
Bumping the rpm up to 1500 or so and showing 13 is more proof it's working.
If you're having trouble with the battery maintaining you should make sure you have atleast a group 27 battery and preferably a group 31 battery to start that engine. And have it tested on a load tester to see if it will hold up.
Customer: replied 2 years ago.
What should the voltage be at idle? My Suzuki 115 4 stroke at idle is 14.0. The yamaha has a long way to idle to get to open water and start charging the batteries.
Expert:  Jeremy R. replied 2 years ago.
It' varies machine to machine. Anything over 12 volts is charging.
If you did away with the regulator output you would be running closer to 10 volts and then lower as the battery died.
If you're running 12.4 it will run fine no matter how long you have to idle.
As soon as it's running and at idle it's charging.