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motor draining battery

15 posts in this topic

I've had 2 Johnson (60hp and 40hp) motors do this EXACT thing to me.

I can't say this is your problem, but the only way to tell is with proper electrical testers.

On these motors there is a round in shape terminal-module thingy that is bolted on the side of the motor, somewhere near the cylinders. There was about 3-4 wires going into this sealed unit which connected to other wires. I want to call this little part the "alternator" for the motor to charge the battery. I don't know the technical name for it. It's a $50-65 part.

The reason why this part blew out on these motors was during installation of the starting battery. If the positive wire and negative wire touch something it isn't supposed to, this little unit burns out.

If this little module doesn't work, the motor will use up the electricity from the starting battery to run the engine.

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Are you positive the motor is the only thing connected to the battery? These wires could be spliced away from the battery and connected to a fuse block some where.

We had a problem with a radio slowly draining the battery.

But I have also seen the rectifier go bad on other motors but those were mostly Mercs. This part is built to prevent current drains, so it is the most likely culprit and pretty much the only culprit if you are confident it is your motor.

[This message has been edited by Grabs (edited 05-08-2003).]

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I would concur... although it's tough to say without some troubleshooting work on the motor.. if I remember right a rectifier isn't a real cheap part. The best bet would be to try and get it in somewhere (if that's even possible anymore) and see if they can look at it quickly... I can't remember how to trouble shoot it, but it is pretty easy to do.

Good Luck!

marine_man

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you can try iboats.com. there are some real experts on their forums.

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You got guages on this boat? Voltmeter? What's it reading with the boat running low-mid throttle?

chunky

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I have a problem.
It seems that my 1999 70hp johnson 3cy is draining all the power out of my starting battery.
The only thing attached to the battery is the motor. It even drains power while just sitting in the yard. Last night i checked the charge level of the batt.3/4 charge and then ran the motor for about 10 min. turned it off and then checked the charge again. Zero.
this started last year and i thought it was a bad battery but put a new one in this spring.
I called a local marine service and he told me it could be many things like my guages in the console shorting out.
Any help would be appreciated before i run it in to get checked out and fork over a load of $$$ to get it fixed.

ORDIE

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I have a 1996 Johnson 90 h.p. with the same symptoms, it needed a new rectifier, $175.00. However, on mine the tach also will not work with a bad rectifier.

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I have my fuel guage and oil warnning and check lights that beep at the turn of the key. Bilge and live well along with the other electronics are on a seperate battery. Troling motor has its own batt also.
It just may be the rectifier, it can be easy to touch the wrong wires to the wrong posts on the battery to fry it. Placement of the battery is in a hard to reach location so i can see if thats it, i may have done it.
Can guarantee that if it costs that much to replace i wont do that again!
I am taking it to Olsons sports in Mahnomen
in the morning, said they could get to it monday or tuesday.
thanks for the prompt replies, again this form has been a wealth of information.
I will let you kind folks know what exactly the problem was after i write the check.
Tight lines to all on opener.

ORDIE

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I just replaced my rectifier for my '94 70hp. Cable were crossed somepoint in time. Twin city outboard $80.

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Got the problem fixed! You guys hit the nail on the head, it was the rectifier.
I gues Johonson had a problem with these going bad quite often and came out with a new one to rectify the rectifier problem.
Any how the part run $190.00 and with labor it came to $240.00!!!!
I think i know what buisness i need to get into when i get out. $50 to change the thing out. and its not that hard to do.
Thanks again.

ORDIE

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My tachometer does'nt work correctly for some reason. The motor (97 Johnson 150hp) runs great!
Battery stays full charge!
I don't run full throttle so should I get the tach fixed or replaced?
As stated above, doe's the rectifier have anything to do with the tachometer not functioning?

[This message has been edited by Finlander (edited 05-22-2003).]

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finlander>
your tach might just be not connected from the boat bouncing around on the water try looking behind it in the dash to see if it is hooked up wire might of came loose or it may not be attached on the motor.. i would check these out first before taking it in.. if you cant get behind tach you should be able to take it out the front and check..

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ORDIE it took me about 10 minutes to replace. I hope you seen my post above. You could've got by a little cheaper. frown.gif
Anyway, I've been told you can actually use a 3.00 recifier found at radio shack that even works better.

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