CDI rectifier less than 1 year old but getting 16 volts, why?!

Odawg753

Seaman
Joined
Aug 9, 2015
Messages
51
hey guys i have a 1990 johnson 150 35 amp. changed the rectifier last year and now this year ive noticed im getting 16 volts which is way too high. it was a CDI rectifier, could it really have gone bad that quick??
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
The rectifier doesn't control voltage, it only converts AC to DC, the voltage regulator limits the volts. I'm not sure if that motor has a separate regulator/rectifier or if they're combined in one unit, but it would be the regulator portion that's not working.
 

Odawg753

Seaman
Joined
Aug 9, 2015
Messages
51
The rectifier doesn't control voltage, it only converts AC to DC, the voltage regulator limits the volts. I'm not sure if that motor has a separate regulator/rectifier or if they're combined in one unit, but it would be the regulator portion that's not working.
im pretty sure its all one in the same
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
51,126
Did you clean the conacts on the battery? A bad contact would cause the regulator to sense low voltage on the battery side.

Also, verify the voltage with a test meter (dash gauges are not accurate)
 

Odawg753

Seaman
Joined
Aug 9, 2015
Messages
51
Did you clean the conacts on the battery? A bad contact would cause the regulator to sense low voltage on the battery side.

Also, verify the voltage with a test meter (dash gauges are not accurate)
yes contacts are clean, tested with multi meter
 

gm280

Supreme Mariner
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Jun 26, 2011
Messages
14,605
yes contacts are clean, tested with multi meter

Have you tried reading that same voltage with the meter set to AC mode? Could be one of the rectifier diodes is shorted? JMHO!
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,612
no expert on battery systems, but charging two banks simultaneously? (e.g., bat. switch on both) If so might see what the output is on just one bank (set on bat1,). Don't switch with the motor running, just to be safe.
 

jakedaawg

Rear Admiral
Joined
Jun 26, 2012
Messages
4,275
Many times a failure is directly related to an operator error. Or an installer error. For example not having the batteries cables tightened with a wrench. Or failure to completely troubleshoot an entire system. Or switching a battery switch while the motor is running.
 
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