View Full Version : 1970s mercury 850 charging issues.

Bill Krummel
08-24-2019, 10:59 PM
I have a 1974 mercury 850 85hp outboard that has been having charging issues. I have tested the stator and rectifier and both test fine but on the output of the rectifier it only reads 11.5 volts, and on the stator only one wire is outputting voltage and its about 6.5 ac. Does this sound right or what could the problem be? My battery has been dieing after every few outings and if i pull a cable off while the engine is running it dies immediately.

08-25-2019, 07:09 AM
Sounds like a bad stator.


Bill Krummel
08-25-2019, 06:10 PM
It may be but what puts me off that is that i have used 2 stators with the same outcome. Both of them are used but how likely is it that both go bad in the same way? Also the cheapest brand new stators is about $275 and would rather not get another old used one.

08-25-2019, 08:16 PM
Keep pulling battery cable off and you will end up buying a $500 trigger!!!!! This ignition/charging system does not operate like a auto system as stator is only about 2 amps at idle and 6- 9amps at WOT. Sounds like a shorted rectifier....