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  Another polarity-crossing question

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Author Topic:   Another polarity-crossing question
skred posted 07-07-2009 12:57 PM ET (US)   Profile for skred   Send Email to skred  
I didn't want to hijack the other thread, but I - too - just had an "incident" with polarity reversal. In the process of reconnecting the various wires to the battery of my 1997 30 hp Evinrude, something crossed the poles momentarily. A "pop" and smoke emanating from the cowling was the result. The smoke had no odor. I connected the wiring as it should be, and tested the starter. It worked fine. I then muffed the motor, and tried starting it. It started and ran fine. Next, I put a voltmeter on the battery. It read 12.59 volts with the engine off, and the same with the engine running (and revving a bit to see if there was a voltage change).
My big question is this: Is it possible this hp range motor doesn't have a charging system? (Not likely, I know...)
I also started the engine, and pulled the battery cable off, and the engine continues to run. I assume because the spark is generated on the engine, it doesn't need battery power once it's running.
Finally - any idea how much those diodes (if any) might cost to have replaced?

skred posted 07-07-2009 01:25 PM ET (US)     Profile for skred  Send Email to skred     
Further investigation shows the 2 red wires attached to the terminal block on the engine (mounted over the rectifier) have a small amount (1/8 inch or less) of their sheathing melted off - which would explain the smoke, perhaps?
L H G posted 07-07-2009 04:25 PM ET (US)     Profile for L H G    
On a brand new Mercury 2-stroke I just installed, they warn against reversing the battery connections. They say Rectifier and possible Switch Box damage will occur.
skred posted 07-07-2009 09:14 PM ET (US)     Profile for skred  Send Email to skred     
Larry, I had that susupicion anyway... I read the other posting here, and Jim's references...
I guess I was hoping that I didn't do too much damage. I took the boat out for a couple hours today, and everything went fine. Now, I'm gonna check the batter level again to see if there's any change...
BTW, what's a switch box?
Chuck Tribolet posted 07-08-2009 09:44 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
If the voltage didn't go up with the engine running, it
didn't charge. It should read in the mid to high 14V
range at reasonable revs.

I'd guess the rectifiers are blown.


Chuck

skred posted 07-08-2009 02:02 PM ET (US)     Profile for skred  Send Email to skred     
Chuck, I'm sure you're right. The rectifier assembly from a place called eBasic Power is $32.00. Not terribly expensive... I took the boat out yesterday, it started normally and ran just fine. I did use my depth finder a bit, but when I checked the battery back home, it read 11.7, so it's obviously not charging, but it's not drawing very much for the locator, either...
skred posted 07-08-2009 02:08 PM ET (US)     Profile for skred  Send Email to skred     
Chuck, I'm sure you're right. The rectifier assembly from a place called eBasic Power is $32.00. Not terribly expensive... I took the boat out yesterday, it started normally and ran just fine. I did use my depth finder a bit, but when I checked the battery back home, it read 11.7, so it's obviously not charging, but it's not drawing very much for the locator, either...

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