Merc 200hp Black Max - battery charging?

[ssale]

Hi,
I have a 1980 Mercury 200hp (Black Max) and after starting and reving it up and down the battery charge voltage doesnt seem to move off about 12.5 volts, ie battery voltage. I was expecting to see around the 13.8 volt figure, like a car battery charging figure. All connections, battery terminals, plugs etc are clean and tight, the motor runs fine however I am a bit nervous about going out to far in the boat in case the battery dies. Any troubleshooting tips on how to figure out what is at fault? Thanks in advance. Happy boating regards Scott, (Sydney - Australia)

 

[hkeiner]

Re: Merc 200hp Black Max - battery charging?

It is likely that the voltage regulators are bad. However, before replacing them I suggest that you confirm they are bad by doing some tests using a voltmeter/ohmmeter. Your shop manaul should describe the various bench tests and engine running tests that can be performed with a test meter. A search of this forum should also provide such information.

 

[j_martin]

Re: Merc 200hp Black Max - battery charging?

Identify the system you have, either rectifier alone, rectifier/shunt regulator (2 units), 5 wire regulator 16 amp, dual rectifier 40 amp, or single rectifier 40 amp (water cooled)

Then we can figure out how to test and repair it.

hope it helps
John