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  Trim Not Working--Nav LIghts Dimming: Related Problem?

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Author Topic:   Trim Not Working--Nav LIghts Dimming: Related Problem?
diverdave posted 10-20-2005 10:58 AM ET (US)   Profile for diverdave   Send Email to diverdave  
I started having a problem with my trim/tilt motor on my 70hp Yamaha 2 stroke, and my nav lights and fishfinder light all at the same time. I assume these are a related problem, I was wondering if anyone could venture a guess as to the problem.
I was trolling for an hour or so and I tried to tilt the motor, all I got was what sounded like trying to start a car with a nearly dead battery...a clicking sound. I noticed at the same time that my Nav lights and fishfinder light were fluctuating in brightness and becoming pretty dim. The problem seemed to clear up after I ran at a higher RPM for a few minutes, but this has happened twice. Does this sound like a loose connection somewhere or maybe a battery issue. Maybe the trim motor isn't getting enough current to work?
jimh posted 10-20-2005 12:31 PM ET (US)     Profile for jimh  Send Email to jimh     
It sounds like the supply voltage to the trim motor is low. This corresponds with the dimming of the incandescent lamps; light intensity is proportional to the current, and this is proportional to the voltage.

A high resistance in a connection can create a voltage drop in the distribution. Or a bad battery can sage when a high-current is demanded from it.

The first thing to check in any battery-powered electrical system is the battery itself.

Bulldog posted 10-20-2005 04:30 PM ET (US)     Profile for Bulldog  Send Email to Bulldog     
When checking the battery , go right to the connections take them apart clean them put them back together and then see what you have.......Jack
ratherwhalering posted 10-21-2005 11:21 AM ET (US)     Profile for ratherwhalering  Send Email to ratherwhalering     
Jack is right, check those battery cables. If that is not the problem, check the ground to the trim motor itself, and the battery cables at the engine end.
Chuck Tribolet posted 10-21-2005 01:40 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
A bad ground at the trim motor won't cause the nav lights to
dim.


Chuck

diverdave posted 10-22-2005 08:40 AM ET (US)     Profile for diverdave  Send Email to diverdave     
Turns out the negative battery cable was loose. I had just installed a new battery box and it was deeper than the old one, so the cables were being pushed up by the top edge of the new box, which caused the negative cable to vibrate loose. I'm guessing that the light fluctuation was either due to the loose connection itself or maybe the battery was not fully charging because of the connection.

Can someone suggest how I can test the battery to see if it is charging or holding a charge. I have a Fluke Meter, do I check voltage as it is not in use, then check it with the engine running? What voltage should I be looking for, I assume 12v while not in use.

Thanks for everyones input.

jimh posted 10-24-2005 10:36 AM ET (US)     Profile for jimh  Send Email to jimh     
If the outboard motor charging circuit is working properly, it should drive the terminal voltage at the battery to above 13.2 volts but not more than about 14.5 volts when the engine is running at fast idle or higher.

In the case of your Yamaha 70-HP two-stroke, I believe that you will find the charging output is unregulated and depends on the battery itself to somewhat limit the voltage. Because of this you may find that in certain circumstances the voltage may be above 14.5 volts, for example, if the battery is already fully charged, the engine is running at high speeds, and there are no other electrical loads operating.

The current output of this Yamaha is modest, about 6 amperes. This is typical of smaller outboard motors of that generation. The electrical demands of boats which use them are typically also modest.

Chuck Tribolet posted 10-24-2005 10:49 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
JimH's approach will tell you if the engine is trying to
charge the battery.

To check whether it is taking and holding chrage,
run it enough to get it well and truely
charged. Then put it on the trailer and go home. Make sure
everything is turned off. The next day, measure the voltage
across the battery. If you google around you can find tables
of charge vs. voltage vs. temperature. Your Fluke, BTW, is
the gold standard of DVMs. Repeat next week.

The light dimmed because of the bad connection at the ground.
The higher the current, the larger the voltage drop there.


Chuck

jimh posted 10-24-2005 11:21 AM ET (US)     Profile for jimh  Send Email to jimh     
You do not have to google for the information; it is right here in the REFERENCE section in the ELECTRICAL subheading:

Battery Charge
This article provides information on your battery, how to care for it, and how to measure the state of its charge.
http://continuouswave.com/whaler/reference/chargeBattery.html

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