Help! Johnson voltage output cable??

[phillyg]

New outboard owner here (1985 Seahorse Sailmaster 8hp). There's a two-wire electrical cable with plug, about 2ft long, coming from the front of the motor housing. Previous owner said its to connect to a battery, and if not connected, something in the motor will burn out, but the motor will still run.

I assume the motor puts out 12v or so when its running. Its pull-start, not electric start, and used only on my sailboat during daylight hours; I do not need to charge a battery.

My concern is about "burning" something out. My ignorance is showing here. Do I just need to rig cables to a small 12v battery (thinking lawn tractor/motorcycle size) in order not to burn out the alternator or generator? If so, is the voltage regulated by the motor so the battery doesn't overcharge? In the alternative, is there some sort of aftermarket voltage "sink" to connect the motor cable to in order to bleed off the voltage and not burn out the motor component(s)?

Thanks

 

[jtexas]

Re: Help! Johnson voltage output cable??

The "something" is called a "rectifier", which converts the AC generated by the alternator into DC for charging the battery. The rectifier won't last long without a battery connected to it. Usually the only problem with a smoked rectifier is that the motor won't charge a battery, but its possible for it to fail in a way that causes it to interfere with the outboard ignition. You could just remove the rectifier - you can always put it back if you decide to start carrying a battery to power things like running lights, fishfinders, stereo, GPS, yada yada yada............

The alternator puts out 4 (or maybe 6?) amp unregulated. It's very unlikely to overcharge a battery (at least, not a marine deepcycle) - in the charging circuit, the battery itself regulates the alternator output. I have no experience with lawn tractor batteries.