Johnson 9.9 Charging system upgrade

Tacklewasher

Tacklewasher

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I've read through the Puget Sound discussion on the 9.9/15 hp OMC motors but have a simple question that is not clear from the article.<br /><br />I have a 1981 Johnson 9.9 basic motor. I've bought a charging system for it off EBay that is from the same year motor (or at least 77 - 81 motor) so I can keep my trolling battery charged when camping etc. I usually run to a spot, troll for a while on electric, then run back to camp so this seems like a good way to keep the battery somewhat topped up.<br /><br />Is this an easy install? The article mentions needing a rectifier but I'm not clear on why etc. I'm not installing a starter (although I'm thinking about it)
 
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Xcusme

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Re: Johnson 9.9 Charging system upgrade

Tackle,<br />A rectifier converts A/C (Alternating Current) into D/C (Direct Current). The voltage output of the parts you bought an E*ay produce A/C voltage. This output voltage must be connected to a rectifier to do the 'conversion'. Since your battery is D/C this is a needed part. Do not try hooking up the output of your charging system directly to your battery. A/C going into a battery will destroy the battery. Adding a starter is OK too. The charging system (and rectifier) keep the battery charged so the starter will have enough voltage/current for subsequent starts.
 
Tacklewasher

Tacklewasher

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Messages
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Re: Johnson 9.9 Charging system upgrade

Guess I wasn't clear as usual.<br /><br />I understand what a rectifier is. I thought that the charging system for these was based on a generator (i.e. putting out DC) and that a rectifier would not be required. Also, if it is needed, is it external to the normal charging systems? It just seems wierd that it would need one.<br /><br />And are they difficult to install? I am trying to find a manual for this motor but haven't located a good used one yet. I can do most repairs but am just curious if I have bitten off a big job (left for over the winter) or something that takes a couple of hours.<br /><br />Fishing season will end soon (which really sucks as our fire conditions have forced me not to fish in the last two months) so am I best to leave this for winter?
 
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Xcusme

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Re: Johnson 9.9 Charging system upgrade

I believe that your system only produces A/C and will need a rectifier. The rectifier is a separate part and bolts to the side of power head. You'll need a connecting block to make the connections between the stator,rectifier, ect. You hopefully got this with the stuff you bought. It's really no big deal, as the terminal strip is just a bakelite strip with screw terminals to make the connections. You will , of course, have to pull the flywheel to change the parts. This may be a project for the winter as the season is quickly coming to a close. A factory service manual is a must for the conversion.
 
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Xcusme

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Re: Johnson 9.9 Charging system upgrade

Yup, There's a rectifier there, it's connected to the terminal strip and has the Red/Yellow wires coming out of it.
 
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