charging system

[Veeder]

Put the volt meter on the engine today. Reads 12.5 at idle and when revved. Found that the positive cable was slightly loose on the engine. Also found the the negative cable from my secondary battery had come off the post while underway.

[phatdaddy]

what does the meter read w/o the engine running?12.5 while running dosen't sound like it is charging to me.

[steplift20]

put the multimeter to the battery without starting anything and it read 12.49, started the motor and it dropped to 12.31 and not charging,
the funny thing about it is when i first changed the voltage regulator it was charging the about a hour later it stopped charging
go figure

[phatdaddy]

I don't know if you can pull the individual components and have them bench tested. I think you have to find out the cause, because you have changed out all of the parts (stator, regulator,&rectifier). You mentioned dual batteries, did you add that prior to the problems, or change out a isolater switch?

[steplift20]

no

[Veeder]

The batteries are at 12.5 if the engine is running or not. If I rev the engine...still 12.5....

[Airslot]

Guys, this is too easy to troubleshoot. *Veeder, got a multimeter? *On an 88 merc 150 the rectifier is right above the switch boxes. *It's held on by a screw in the uperleft and lower right corners. *Has 3 terminals on it. *

With your battery switch off, discconect all of the wires from the rectifier, 2 wires on each terminal. *Two reds and the + terminal (lower left), a grey and a yellow (upper right?) and a tan and a yellow (lower right).

THe two yellow wires go to the stator. *You test for continuity between the two wires and then between each wire and ground.

The rectifier is tested without removing it. *There is a series of tests that go between the terminals. *I'd have to have my book to toell you exactly what they were. *A new rectifier is $37.50, a stator is about $180. *Most times when a stator goes it will take the rectifier with it. *Sounds like a bad rectifier to me.

Airslot

[steplift20]

you sound like you know what your taking about
i will change the rectifier,the only problem i have is that i was taking to some one at merecury and they told me it would not be the rectifier because the only thing the rectifier does is change the current from ac to dc or dc to ac you know what im talking about
but i know a wire goes from the regulator to the rectifier and i will change it
thanks
i will let you know how i make out

[Veeder]

Airslot,

Thanks! Changed out the rectifier and solved the problem. Tech said that's why my tach got smoked. New rectifier in place, no problems. Just need to replace the tach. Engine still sounds like a dragster,though..

[steplift20]

hey veedwer do you have the same problem i have because i started this topic and you got the answers