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1976 115 Johnson unregulated voltage - how to fix
Recently I had an agm battery go bad that I was using for starting and other accessories. It was pointed out that my engine could be overcharging my agm battery causing failure. The agm battery I was using would out gas if voltage over 15. After an on water run last week, it was clear at higher RPMs my voltage was running over 16-17 volts (per my hummingbird locator)...not using a multimeter. Anyhow,after searching a lot on the internet, it seems that this motor only has the small round rectifier, and no regulator. Supposedly, overcharging on these older engines is a known problem, and a regulator kit is available ( part 173640) that remedies this situation. I tried to look online and see if I could find any instructions on mounting this kit. I am assuming that this is a rectifier/regulator combined . I was wondering if any of the johnson/evinrude mechanics on this board have ever installed this upgrade, and is it just a matter of removing the little round rectifier and replacing it with this regulator.... or is this an added part and the old rectifier stays? If any of you have experience with this, please advise. Thanks.
HHD
GnawMart Tenderloin Sandwich Prostaff, Gnawbone Indiana
Super Mod and 2014 Crappie.com Man of the Year
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I believe that is a regulator only. And being a BRP part it is expensive. You would be better of with something like this. Sierra International 18-5827 Marine Regulator/Rectifier for Johnson/Evinrude Outboard Motor : Amazon.com : Automotive You are correct about that being a common problem with a rectifier only system. Very clean and tight connections on a regular starting battery usually fixes the problem too.
Fair Winds and Following Seas
Bill H. PTC USN Ret
Chesapeake, Va
Slabmaster II
I had the same issue with my older merc. It would charge 17 volts with no accessories on. The older engines relied on the battery to act as a voltage sink for excessive voltage. On a vented battery they don't normally cause issues due to the minimal amp output. I installed a voltage regulator kit from Marineengine.com. There is a ton of info on their forum that is engine specific. I would recommend searching there for the simple fact that 100's of their members have already done it and can tell you exactly what part and tools needed to accomplish the task.
My engine charges with more amps to replenish the battery quicker and stays at a consistent 13.8 volts.
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Thanks fellas for the info and tips. After searching, I found a 12 amp upgrade kit (original is 6 amp) made specifically for this 76 model that included the mounting plate, screws, regulator, rectifier, 12 amp stator for $120. Just waiting to get it now and see how it goes.
HHD
GnawMart Tenderloin Sandwich Prostaff, Gnawbone Indiana
Crappie Wall Hanger II - Moderator Mechanics forum
Hey, if you haven't done it yet. Would you mind taking pictures and doing write up on it. That would be a dandy one to do one on for the forum. Lots of those ol' johnnyrudes around still. You can't beat them imho.Originally Posted by Hoosier Hog Daddy
"But if serving the Lord seems undesirable to you, then choose for yourselves this day whom you will serve, whether the gods your ancestors served beyond the Euphrates, or the gods of the Amorites, in whose land you are living. But as for me and my household, we will serve the Lord.” Joshua 25:15
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