Charging system help please!!

[Coral Reefer]

confused:I have a 1972 Johnson 65 hp Hydro electric shift. How can I tell if the charging system is working correctly? The last time I took it out The battery died and I had to row it back in. I'm hoping it was just a bad battery. Is there a particular voltage to look for and how should I test it? I replaced the rectifier and had no change in readings. The stator is fine I believe as it runs just fine without a battery. When I have the motor running I get 10.7 volts at the battery cables without a battery. Shouldn't this be about 14 volts or so? Also, when I turn on the bilge pump with battery connected the voltmeter goes from 12 to about 10. If I disconnect the cables to the motor, and turn on the bilge the meter goes from 12 to about 11.9 volts.

Thanks, Jeff

 

[Joe Reeves]

Re: Charging system help please!!

Running that engine without a battery is a ideal way to destroy the charging rectifier. Do not do that.

Easy Test..... Have battery connected. Engine not running. Connect volt meter across battery terminals and leave it connected, make a note of the voltage reading. Start engine and observe volt meter, the voltage level should increase. If no change, the charging system is not functioning.

 

[Coral Reefer]

Re: Charging system help please!!

That is exactly what I did. I get 12.8 volts not running and 12.1 to 12.7 volts running. When I kick on the bilge pump it drops to 10.8 or so. without the engine running it drops from 12.8 to 12.7. These readings were taken with a brand new rectifier and were exactly the same as with my old one. Is there something else that could cause this? what about the "monkey balls" diodes?

Thanks, Jeff

 

[tashasdaddy]

Re: Charging system help please!!

the motor puts out very little charge at idle. any significant charge is above 2000 -2500 rpms. don't try it on muffs or out of gear, you could get a runaway motor.

 

[Joe Reeves]

Re: Charging system help please!!

Temporarily connect the red (+) lead of the voltmeter to the RED wire of the rectifier with the black (-) lead of the voltmeter attached to a powerhead ground to check the polarity at that point. Hopefully it is not reversed.

Double check the new rectifier as follows:

(Small Rectifier Test)
(J. Reeves)

Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.

Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.

 

[Coral Reefer]

Re: Charging system help please!!

Thanks Joe, I'll try this new test later if you think I need to.

I tested the rectifier with a digital multimeter on the diode test setting. It tested as follows first number one direction and second number is leads switched. I think it is ok. Is there anything else such as a broken wire between the engine and controls that could cause it not to charge? If so, any idea which color wire?

Test results:

Yel- case= 1 & 533
Yel/gr - case= 1 & 514
Yel- Red = 1 & 530
Yel/gr- Red= 1 & 535

This is good correct? Also the shift diodes (hydro-electric shift engine) Test bad I think. Will this effect the shifting or not?

Shift diodes test results

Yel- Green = 1 & 490
Yel/blk - Green= 1 & 1
Yel- Yel/blk = 1 & 1

Is this blown?

Thanks, Jeff

 

[Joe Reeves]

Re: Charging system help please!!

I've never used a digital meter and have no idea what those numbers mean. I've always used a analog (needle) type meter on a high ohm setting. This gives me a reading or no reading which is what I would be looking for.

 

[Coral Reefer]

Re: Charging system help please!!

1 is where it starts out therefore the 1's are the same as no reading.