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50hp outboard charging?

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Sunset Cruise

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I bought a pontoon a year ago with a 1980/1981 50 HP electric start outboard. (Serial # 5832737) This years project involves installing navigation/anchor lights, battery #2 and a battery switch- nothing else was drawing on the battery other than starting up. When preparing to install the battery switch I noticed the battery cables to the motor were not colored positive or negative so just to be safe I did some research (on this forum) to verify the motor wouldn’t run if the battery was connected wrong. Went down to the boat today to check the battery charging as one method to be sure and the readings (12.4 before starting, 12.04 at idle and revved up) prompted more questions. The boat’s battery has been connected this way for more than a year without issue.

My questions:
1) is it even possible for this motor to run with the battery cables reversed?

2) If the cables are connected properly, do the voltage readings lead you to believe I have a bad diode or other problem with the charging system?

Thanks in advance for your help.
 
(12.4 before starting, 12.04 at idle ) it's not charging so the rectifier is probably done - (the voltage should rise to 13v or more after 1500 rpm) or the stator is bad, take a voltage reading across the yellow wires on the rectifier it should be 14v or more. Is the battery switch a marine make before break one? this is the only type to use. I think that is an ADI ignition that doesn't use battery power to work it's self energizing.
 
Quicksilver said:
(12.4 before starting, 12.04 at idle ) it's not charging so the rectifier is probably done - (the voltage should rise to 13v or more after 1500 rpm) or the stator is bad, take a voltage reading across the yellow wires on the rectifier it should be 14v or more. Is the battery switch a marine make before break one? this is the only type to use. I think that is an ADI ignition that doesn't use battery power to work it's self energizing.
Click to expand...

Thanks Quicksilver- I’ll run the tests when I have time to get to the boat. With regards to my first question, would the motor start/run if the battery cables were backwards?
 
The starter might not engage the flywheel to start the motor.-----But you could pull it over with a rope and it would run.
 
racerone said:
The starter might not engage the flywheel to start the motor.-----But you could pull it over with a rope and it would run.
Click to expand...

Quick update- ran a voltage test again this morning (boat is still in the water)

12.22 V before starting
12.10V at idle
12.18V at medium rev (no tach)

Thought I read somewhere these motors with a full wave rectifier virtually act as a trickle charge to the battery?

Gonna go out on the lake later and take measurements at full rev and a longer cruise.
 
Those readings are too low for a functioning alternator which will keep a charged battery up, don't let the alternator charge a lower than 9v battery the battery should be fully charged for use. Did you check the voltage coming from the stator?
 
Thanks Quicksilver. The boat is still on the dock so I'll need to pull it out of the water (using the marina's trailer) or figure out a way to access the motor from the dock to test the rectifier and stator. I'll make sure to charge the battery up. Regarding your previous question regarding the battery switch, the one I purchased (not yet installed) is "Blue Sea Systems 300 Amp m-Series Battery Switch"
[h=1][/h]
 
Closing the loop on this thread, installed the new rectifier yesterday and now charging at 15.3 volts. Fairly straightforward job, the cowling removal/installation took as much time as replacing the rectifier. Always appreciate this forum and those willing to help others.
 
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