Anyone know anything about outboard charging systems?

mnmfors

Petty Officer 2nd Class
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Nov 18, 2001
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176
I have a problem with a with a merc 90, 1985. I am willing to troubleshoot to save coin, if you have the time.
 

Trent

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Nov 17, 2001
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Re: Anyone know anything about outboard charging systems?

Whats the problem..? Overvolt, Undervolt? Is the tach working?
 

mnmfors

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Nov 18, 2001
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Re: Anyone know anything about outboard charging systems?

It just stays at 12v. It does not move when the motor is running. Slowly drains over the course of the day. It really doesnt bother me to switch batteries, but after reading other posts about the electrical system, I am comvinced this prob with mine will lead to other problems. I have recently replaced the voltage regulator. This cured another problem, but not the charging prob., any suggestions on where to start? I am fairly certain that it is not the battery, as two of the three I keep in the boat are new. I would be greatful for any help.
 

petryshyn

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Oct 3, 2001
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Re: Anyone know anything about outboard charging systems?

mnmfors<br />There are about ten different variations of charging systems out there. Unfortunately, I'm not sure what you have. If you post a schematic or describe what you have, I can guide you in testing it. Unless someone else knows your exact system.....they can help.<br /> :)
 

mnmfors

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Nov 18, 2001
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Re: Anyone know anything about outboard charging systems?

Thank you, I have a stator type charging system. It has two little yellow wires that come from the stator to the voltage regulator. It does not have an alternator like some I have seen on newer, bigger mercs. Is this enough info, or do I need numbers, and where should I look for these numbers? or...need a picture?
 

petryshyn

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Re: Anyone know anything about outboard charging systems?

is the rectifier and regulator one unit?
 

mnmfors

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Re: Anyone know anything about outboard charging systems?

I am not sure, the voltage reg is about 2"x2" and has three leads.
 

petryshyn

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Re: Anyone know anything about outboard charging systems?

two leads from the stator go to reg.....the other lead from reg goes where?
 

mnmfors

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Re: Anyone know anything about outboard charging systems?

Ok, It is raining here, and my light is not working. I was able to find a red wire going to the solenoid switch. does that help?
 

petryshyn

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Re: Anyone know anything about outboard charging systems?

OK...the stator generates an A/C voltage which is rectified by the rectifier/regulator assmy. I'm not sure if you actually have a rectifier-regulator assmy. or just a rectifier. This won't make much difference in trouble-shooting at this point.<br /><br />stator > A/C > rectifier > D.C.<br /><br />>start engine, 1500-2000rpm, measure voltage at battery POSTS with voltmeter. Don't rely on dash gauge. (too many factors skewing results)<br />>measure voltage at red lead of rectifier(red lead to red lead, black lead to rectifier case or mounting bolt.<br />>switch volmeter to read A/C volts and read voltage between the two yellow leads from the stator(engine still running)<br /><br />get back to us with results.........<br />and stop bragging about the rain!!!!! its snowing here!!!<br /><br /> ;)
 

ODDD1

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Jan 23, 2001
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Re: Anyone know anything about outboard charging systems?

lucky boy, schematic...I got my sled ready yesterday!...this guy has an unregulated system...just a bridge rectifier and on a good day it will only put out about 9 amp....at WOT....at idle it is more like 2...if mnmfors is running alot of accy, the system may be fine, he is just beyond capacity......<br />an AC voltage check between the 2 yellow wires is what is needed....the rectifier has been replaced, assuming it is ok, you need about 20 volt AC to feed it.....
 

petryshyn

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Re: Anyone know anything about outboard charging systems?

Thanks ODDD1<br />I know, I know, I should have payed more attention in school, but just how far south of the Can. border is Fond du lac, wisconsin?<br /> We got 4" of snow, overcast, windy and about -5F. <br />Sure could use some sympathy.....LOL.<br />(might be hard to get from a 'sledder')!!!!LOL
 

mbb

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Apr 20, 2001
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Re: Anyone know anything about outboard charging systems?

you usually see 2 problems with this system, the alternator wires fail, or the rectifier is fried (it only takes momentarily connecting battery leads backwards). A new rectifier is $35. <br /> You check the rectifier when not running as follows:<br />1. disconnect all leads from it<br />2.one terminal is marked + on rectifier, you use ohmeter to check for continuity as follows, on 1000 ohm scale:<br />3. red ohmmeter lead to ground, black alternately to both terminals that are not the + terminal on rectifier, should be no continuity.<br />4. Black ohmmeter lead to ground, red test lead alternately to both non + terminals on rectifier, should be no continuity<br />5. red lead to + terminal, , alternately test black to both others, should show no continuity.<br /><br />replace if any continuity shows in the above tests.<br /><br />Check the alternator coil with an ohmmeter across the yellow/red leads (while disconnected) should be less than 1 ohm.<br /><br />connect red lead to a stator lead, and black to ground, should be no continuity.
 

12Footer

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Mar 25, 2001
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8,217
Re: Anyone know anything about outboard charging systems?

I have found the rectifier cube bad on all three of the mercs I werked on with this problem. And it was caused by placing too much demand on the charging circuit,which was caused by running multiple underwater lights (Headlamp bulbs) in crapi season, total current drain with the lights and nav lights was 9-12 AMPS, and they kept comming back with dead batteries and fried rectifiers,and you were right also about the stator wires burning in two, even on the larger Mercs.<br />We fixed it by supplyng small gen sets,and going 10VAC. But then,we were like everyone else, attracting as many bugz as crapi.These were all 1978 models, so there may be monumental differences.
 

mnmfors

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Re: Anyone know anything about outboard charging systems?

Thank you all for the input, I had a problem with my waterpump as well, so I am fixing that first, before I run the engine for the necessary tests. I will post again within a few days, with the test you requested, schematic and mbb. Please bear with me.<br /><br />as far as too many accessories, I only run my gauges, tilt and trim, bulge pump, and running lights (only on occasion). all of the fishing lights etc, I hook to another battery. However this is a hydrostream boat, I think a '79. Maybe it wouldnt be a bad idea to go through all the wires and replace them. Or at least test them for shorts.<br /><br />Schematic, sorry about the weather thing, but nothing is worse than working on your boat in this kind of weather. :(
 

petryshyn

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Re: Anyone know anything about outboard charging systems?

OK OK I was bored......Do these checks with engine running at 1500-2000rpm<br />
system.gif
 

Dan29072

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Aug 18, 2001
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Re: Anyone know anything about outboard charging systems?

Hello, sorry to here about your charging system. I have a 90hp force with the identical problem. I had a certified mechanic work on my charging problem. It has the identical problem as yours. I replaced the stator,rectifier,3 coils, alternator I also took posts from this bulletin board to show the mechanic. for over three weeks he worked on it. replace all the above at least twice. He told me he fixed it and when I put a volt meter on it. It still was not charging properly. at WOT it may be 12.2 volts at the battery and all I run was a radio. So now I make sure my other batteries are charged and do what you have been doing. If you ever do find the one little thing that screws up the charging please email me dansimpson@mindspring.com<br /><br />Thanks<br />Dan
 

petryshyn

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Re: Anyone know anything about outboard charging systems?

Dan29072<br /><br />You may have nothing wrong with your charging system. It could be the supportive wiring between the rectifier and the battery. Do the above tests and reply with your readings....<br /><br /> :rolleyes:
 

mnmfors

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Nov 18, 2001
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Re: Anyone know anything about outboard charging systems?

ok schematic, got engine running and cooling good, did your test.<br /><br />Battery....10v<br />red lead dc...9v<br />stator ac...20v<br /><br />I know that the battery should read 12v, I am charging it now, let me know if I need to retest.
 

petryshyn

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Re: Anyone know anything about outboard charging systems?

hi mnm<br /><br />Looks like the stator is putting out. Either the rectifier is bad, or wiring from it to the battery. Be sure to charge battery before further testing. A "dead" or "low" battery is often the cause of charging system failure.<br /> Take a voltage reading right at the rectifier. Negative lead on mounting bolt and red lead to red output lead. If this reading is less than 13 volts while running, we'll do a rectifier diode test next. If rectifier is bad, we'll talk about a better cheaper alternative than OEM.<br />
system2.gif
 
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