Burned regulator!

garbubba · #1 01-25-2013, 11:24 AM

Well I finally got off my butt & dug into why my outboard (94 merc 200 offshore) wasn't charging.

Took the hood off & found that it had been hot right above the regulators, the bottom regulator was COOKED & melted,(looks like it may have even been on fire) The top looks damaged too, I'll test it but replace it either way.

What would be the most likely cause of this? Would it just be the regulator giving up or would it be overcharge from the stator?

Doug

THEFERMANATOR · #2 01-25-2013, 01:06 PM

Bad ground can definately ruin a regulator.

tsubaki · #3 01-25-2013, 01:07 PM

I know I'm not going to describe this correctly. At least FERM will straighten it out.
A stator may produce an over voltage due to the rpm's and the regulator is used to keep the voltage within a certain range during the rpm fluctuations.
A regulator may become defective or damaged for whatever reason and let the full voltage from the stator pass through or not any at all.
Now, why is the regulator damaged? That can be a booger to determine.
Is it possible the batteries are too large or weak and needing voltage constantly or might there be a heavy current draw from other things in the boat?

tsubaki · #4 01-25-2013, 01:08 PM

FERM, you are on point.
Straighten me out!

THEFERMANATOR · #5 01-25-2013, 01:41 PM

Not sure on MERCS on how they cool them, but on OMC's they mount into the engine block in teh V where the water is the coldest. I thought MERCS worked simliar and needed a good clean contact to the exhaust divider for the regulator to keep the diodes cool. The stator puts out about 30-35 volts AC, and then runs it through the diodes to convert it back to DC(you need about 16 volts AC to make 13 volts DC at low amperage due to diode loss). If teh regulator doesn't have a good ground, it cannot regulate the output correctly causing alot of voltage swings coming out of the diodes. So either you didn;t have a good contact on your ground, or your regulator wasn't making good solid contact to the divider for cooling of the diodes.

garbubba · #6 01-25-2013, 05:09 PM

Thank you guys,

Ferm, they (it's a 40 amp dual regulator system) mount to the back of the water jacket with heat sink grease, like you said, that all looked fine, even after it burned.

Loss of ground is likely though, I spent some time working on wiring last summer, it was a mess.

I looked at the stator & nothing looks damaged there.

Shouldn't be the batteries, I use two & don't run much stuff, fish finder, radio, GPS & I put them on a charger at home. That was why I didn't even notice for a few (maybe more) trips out. My voltmeter gave out a while ago. Reality hit last trip out when I flooded it out offshore & heard the batteries start to weaken as I was cranking it.

So that should mean if I troubleshoot my wiring (some was burned) & make sure I have good ground, then a pair of regulators & I should be good (theoretically) right?

garbubba · #7 01-25-2013, 05:13 PM

One more question, anybody have a source for a merc regulator? I saw some on Ebay - about $125.

I believe the part # is 815279T

Thanks again!

tsubaki · #8 01-25-2013, 05:29 PM

Also cross reference a CDI part.
http://www.marinepartssource.com/new...ge%20Regulator
FERM helped me out on a Mariner and did stress the mounting/grounding on one that looked like it.

tsubaki · #9 01-25-2013, 05:36 PM

My problem was the electronics were cutting out about the time we got on plane. The voltage climbed to over 18v and everything not related to the engine was shutting down.

phatdaddy · #10 01-25-2013, 07:17 PM

bigshrimpin used to be a good source for older merc/mariner parts, might pm him and see if he has any left.

kinda strange having 2 bad grounds at once. one might have been out for a while