1989 j90tlcem not charging batteries

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BOBBYJOSEPH

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Sep 10, 2013
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Purchased a 1989 Sylvan last year with a J90TLCEM and a 9.9 kicker. Engines run ok but batteries run down and require a fresh battery to start the j90 at end of day. The boat has a "Guest" battery selector switch with 4 positions: 1, 2, both, and off. In researching this, I've read that you should never switch batteries while the engine is running. I don't think I have, but cant guess what the previous owner may have done. Does this switch maintain contact without disconnect when changing from "battery 1 or two to "both"...Also, in the parts diagram, Item # 66 is described as a rectifier...what is it's purpose? It dosen't seem to be mentioned in the Seloc manual troubleshooting section.
 
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Daviet

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Sep 24, 2008
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Re: 1989 j90tlcem not charging batteries

Welcome to the forum.
You are correct in that with most battery switches you should not switch them with the engine running, it creates an open circuit for a second and can cause problems.
Have you checked the output of the charging system to see if it is putting out any voltage with a volt meter?
Long story short, the rectifier is what charges the battery.
 
Tim Frank

Tim Frank

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Jul 29, 2008
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Re: 1989 j90tlcem not charging batteries

The "alternator" (various combinations) puts out AC current.....the rectifier modifies that to DC.
 
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kjdunne

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Sep 22, 2007
Messages
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Re: 1989 j90tlcem not charging batteries

There is a rectifier testing procedure by Joe Reeves in the Frequently Asked Questions section at the beginning of the Engine Repair and Maintenance forum. That's what to start with.
 
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BOBBYJOSEPH

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Re: 1989 j90tlcem not charging batteries

Thanks, KJ for the reply, the test procedures that I found by j reeves appear to be pertaining to ( small rectifier, non water cooled) and the other to tachometer problems. Is the procedure for testing the small rectifier valid for the water cooled type? ie. if I have resistance one way and not the other when testing the yellow//yellow grey leads can I assume that the rectifier is ok?
 
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kjdunne

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Sep 22, 2007
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Re: 1989 j90tlcem not charging batteries

The water cooled ones also have a built in regulator. I'm not sure about how to properly test them. I'm sure somebody who knows will jump in and help.
 
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