1990 johnson 88spl overcharging

[jeff6264]

I hope someone can help a little. I've run this motor on my pontoon for 3 years without any issues. The other day my depth sounder was reading my voltage at 16vdc. I can turn on accessories and bring it down to an acceptable level 13 to 14. I run 2 batteries both deep cycle both brand new with brand new cables. My battery switch is standard. 1 or 2 or both. When I run with either battery the voltage is high15 to 16. When I run with batteries combined voltage is great at 13.9 to 14.5. Before I start replacing parts does anybody have an idea as to where I should start.

 

[rothfm]

Re: 1990 johnson 88spl overcharging

I had a 1995 88spl, correct me if I'm wrong and maybe this wont help....but I believe they are not voltage regulated. Rectifier only and output can vary depending on flywheel speed. I can remember mine ranging from 13-16 or so. generally didnt cause any issues.

 

[boobie]

Re: 1990 johnson 88spl overcharging

Those mtrs were known for that with just a rectifier on them. Brp makes a voltage regulator, 173640 but the price is high. I know cheaper ones are out there. Maybe somebody will chime in with more info.

 

[stevenvalerie]

Re: 1990 johnson 88spl overcharging

My 115hp johnson is rectifier only. I am not sure about your motor buy I know that with mine you are not supposed to hook it to a deep cycle and/or maintenance free battery as it will cause an overcharging issue. I recently tested this to be true. With a regular starting battery I would get 13v while running down the water. I hooked it to a sealed deep cycle battery and would get 13v at idle but over 16v running down the water. You might try to hook your motor to regular starting battery to see if that changes anything.

 

[metriccrescentwrench]

Re: 1990 johnson 88spl overcharging

Those mtrs were known for that with just a rectifier on them. Brp makes a voltage regulator, 173640 but the price is high. I know cheaper ones are out there. Maybe somebody will chime in with more info.

That same rectifier is used on a lot of different engines. I replace one on my '81 90 HP, was able to find it on ebay at a good price.

 

[jeff6264]

Re: 1990 johnson 88spl overcharging

Ok I was finally able to stop by the local marina and was told by both mechanics that my voltage is normal. This is actually the first time I have new batteries(correction my #1 bat is a starting battery not deep cycle) new cables and all my connections are good. They said there is no resistance from corrosion so a higher voltage. The parts person at the marina showed my motor to have regulator/rectifier combo. My manual shows it as a rectifier. Going to pull cover and see with my own eyes. Thanks for the help!!