Need some info on a 1978 Johnson 150.

[Mike71glastron]

What should the alternator output be on this motor? I have heard it should be in the 17 to 18 volt range. If I am running stereo equipment and other electronics onboard do I need to install a voltage regulator? Where do I find one that will work with an outboard motor?

 

[seahorse5]

Re: Need some info on a 1978 Johnson 150.

The battery size is the regulator for your particular outboard. Do not use a sealed or maintenance-free type. You need a traditional flooded-cell battery in which you can easily add distilled water. Dual batteries wired in parallel work great or get a group 27 or group 31 size.

Many folks today do not remember unregulated charging systems and we didn't have the sensitive electronic accessories either back then. We would also turn the boat's lights on to help lower the charging voltage if it climbed too high.

 

[Mike71glastron]

Re: Need some info on a 1978 Johnson 150.

Thanks for the info but let me rephrase... I have a 1971' Glastron V177 that I have basically rebuilt from the ground up. It was an I/O boat now it holds a 78' Johnson 150 outboard. I grew up with these motors on my dads and uncles boats and they never had a problem with batteries or overcharging. The difference is, my boat has interior accent lighting, Bait tank pumps, depth finder, spot lights, and a 2900 watt stereo system in it as you would find in a boat nowadays. I have spent quite a bit of money on all this stuff and I am concerned that I will fry something if I don't regulate the voltage somehow. Is there a way to do this? What do you think about running optima yellow top marine deep cycles? I need that kind of juice.