Charging output of 1982 115HP Mercury 2 stroke outboard motor.

Thank you in advance for any insight on this topic. I did a battery test with an AVR tester. During the test it asks for a RPM increase to 1500 to test the charging system. The test result on this showed 12.7 volts. I use this tester on a daily basis but with automobiles and I know that with automobile motor the test should be somewhere between 13.2 - 14.6 volts showing a good alternator. This is my first boat and I know sweet nothing about the motor. What should be the charging volts from the motor to the battery. 1. At idle? 2. At full speed?

Just a note: I have been having to boost the battery after a few days to start the engine. I drove at a low idle for about 15-20 minutes. Shut down the motor and 1/2 hour later had to boost the battery to restart. After restarting engine I drove for 15 minutes at 3/4 to full throttle, shut the engine down and was able to restart the motor. Next morning had to boost again. I am almost 100% sure that my battery is pooched but do need clarification on charging output. Thank you.

Basically it's the same as an auto - 13.4 to 14.6 volts output. On that engine, all that it is doing is charging the battery to the best of my knowledge. I'm not sure of that particular setup, but check the regulator/rectifier first.

I'm not sure if Chris at Dockside Marine Services monitors this forum or not, but he is very knowledgeable about these engines. You can post a private message top "Docksidemarineservices" on this forum.

Chris
Dockside Marine Services
Jersey Shore.
Mercruiser/Mercury Certified