Batteries

[onefastbiker]

I have a 1956 30 HP Johnson electric start outboard. This weekend I was asked why I was using a 12 volt battery. This person thought I should be using a 6 volt battery instead. I looked through my service manual and the only reference to 12 volts was in the starting solenoid. The boat came with a 12 volt battery that I replaced. Being new to these old motors and systems what voltage battery should I be using????

[billy-j]

Originally the 1956 Johnson 30 HP. was 6 volt. But over 60 years some things could have been changed on your motor. The 6 volt starter motor will operate on 12 volts with no problem as long as the engine is in good operating condition and starts normally. But if you have to crank the engine abnormally long to get it started over time you may have an issue. I would look to see if your starting solenoid and the electric choke solenoid on carburetor are 6 or 12 volt. Originally all parts were 6 volt. If you want to operate engine on 12 volt and the electric choke solenoid and start solenoid are 6 volt I would replace them with 12 volt parts. you could use the parts from a 1957 engine as this is when they changed to 12 volt. I have a 1956 30 HP. and started it it for years on 12 volt I just would choke it manually on engine and not use the electric choke and my solenoid was an original 6 volt and there is a screw cap on the bottom of it that could be unscrewed to reveal a manual solenoid button that I used to crank engine. Never had a problem. I now use a 6 volt battery for the sake of originality but it is awkward if you want to use 12 volt devises such as fish finders or radio’s Regards Bill,

[lindy46]

Original 6 volt starter for that motor was an Autolite 4001M. It has a removable metal band around the bottom to access the brushes. As mentioned, it will work with 12 volts, just don’t overcrank it. You should use 12 volt solenoids if you’re using a 12 volt battery.

[outbdnut2]

SiInce the starter motor has a complex inductive reactance when spinning, it does not draw twice the current at 12 volts than at 6 volts. The current is somewhere in between, so 12 volts works fine. I have also converted a couple old 6 volt cars to 12 volts without replacing the starter. The 12 volt replacement starter solenoid is Sierra #18-5807.

http://www.iboats.com/mall/partfinder/?cart_id=311464734&gd_grid_id=1729&gd_poid=111828&gd_row=17&session_id=630306354
Dave

[amuller]

Has anybody asked whether you have a generator installed? If so, everything becomes quite a bit more complicated. Assuming you just have a starter and solenoid, it’s pretty simple. There are lots of 6 volt starters successfully running on 12 volts, and lasting. Usually you get quick starts because the engine is being spun faster, whereas 6 volt systems often seem to provide sluggish cranking–though I haven’t heard of that being much of a problem in outboards. You could add a resistor in the solenoid coil circuit, but solenoids are cheap.

[garry-in-michigan]

There was never a provision for a generator on the ’56 30 horse outboards. If it has a generator, some one has switched the powerhead with a 35 and everything is 12 volt. As previously stated, a 12 volt battery spins a 6 volt starter faster giving quicker starts. HOWEVER – continuous cranking will overheat the starter motor and melt the solder that holds the wires to the commentator, ruining the starter. . . 😉

[Author]

Posts