Outboard charging system

[whirlypig]

I have a 65 HP Merc, 3 cyl, 2 cycle, outboard motor. 1970's I think. It runs as smooth as a sewing machine. It has three batteries, one for motor, two for accessories and 24 volt trolling motor. The only switch I have for monitoring the batteries is three way switch. Off, Main, Aux1, Aux2. The voltmeter is installed on the panel and when charging with the battery charger, it reads 14volts. This is normal for the charger. I was running on the lake and decided to test the main battery and noticed that the volmeter was in the red at 16 volts or close to it.

Obviously the battery is being overcharged by the motor. I don't know much about the charging system on the motor. Is there a regulator? Can it be adjusted? does it use a starter/generator? or another type charging system? I have ordered a manual, but would like some info. thanks..Whirlypig

 

[BLU LUNCH]

Re: Outboard charging system

Some of the early motors had no voltage regulators. So when your on plane turn something on to use the extra juice. I had a 74 85 Hp Johnson over 4000 rpm it was putting out 18-19 volts but the amperage is very low output. Don't worry about it, turn something on to use some up..........

 

[j_martin]

Re: Outboard charging system

Some of the early motors had no voltage regulators. So when your on plane turn something on to use the extra juice. I had a 74 85 Hp Johnson over 4000 rpm it was putting out 18-19 volts but the amperage is very low output. Don't worry about it, turn something on to use some up..........

Actually, they will go all the way up to 90 volts or so. They rely on the battery to limit the voltage. The excess energy hydrolyzes the water in the electrolyte. With regular battery maintenance it doesn't seem to hurt battery life much.

If the battery voltage goes above 15.5 or 16, it indicates that the battery is either near end of life or low on electrolyte.

hope it helps
John

 

[whirlypig]

Re: Outboard charging system

Thanks for the information. I always use my toys until they are completely useless, or become dangerous. It leaves more in my coffers to play with, besides, fixing things can be fun. I couldn't find what looked like a regulator on this motor and was wondering about it.

Jon, I hope not, the battery is brand new and checks out with hydrometer and voltage meter. But, will keep in mind, sometimes new doesn't work too good. Thanks, Whirlypig

 

[Barnacle_Bill]

Re: Outboard charging system

Thanks for the information. I always use my toys until they are completely useless, or become dangerous. It leaves more in my coffers to play with, besides, fixing things can be fun. I couldn't find what looked like a regulator on this motor and was wondering about it.

Jon, I hope not, the battery is brand new and checks out with hydrometer and voltage meter. But, will keep in mind, sometimes new doesn't work too good. Thanks, Whirlypig

The most common problems to cause high voltage in those unregulated systems are bad/dirty battery connections and the wrong type battery. It must be a marine battery.