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Alternator output

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arcrat

Contributing Member
hi all i have a90 hp 3cyl 1987

hi all i have a90 hp 3cyl 1987 and i was conserned about alternator output. thanks for any replys arcrat this site rocks!!!!!!!
 
"What is your concern?

This

"What is your concern?

This model had a (standard) stator used on 3 and 4 cylinder models which served double duty. It produces the ignition voltages from some of the windings and (alternator) voltages from some of the others.

So part of the stator is wired to the ignition system (coloured wires) and there are two Yellow wires that feed the rectifier (to ultimately charge the battery etc).

You generally don't measure the output on the ignition side unless you are troubleshooting.

On the charge side of things - after the rectifier, you would normally see 13-14 volts when the motor is running...."
 
one batt i had in the boat it

one batt i had in the boat it boiled acid out that way i was concerned .thanks for all your help.
 
"No, that's too much - rep

"No, that's too much - replace the rectifier (that black square thing that has the two yellow wires feeding it and the red going over to the starter plus possibly a 4th wire, gray or purple maybe that feeds the tach).

It is a generic Merc rectifier on that model, so any Merc dealer or there are numerous aftermarket sources as well.

You can usually pick one up for between about 25-35 bucks..."
 
THANKS GRAHAM I THOUGHT THERE

THANKS GRAHAM I THOUGHT THERE MIGHT BE A PROBEM WITH THE CHARGEING. I AM GLAD YOU TOLD ME ABOUT IT. THANKS AGAIN I WELL PULL COVER AND CHECK IT OUT.
 
"They will overcharge if the b

"They will overcharge if the battery is on its way out, like if its out of water. Best to keep a small load on the system all the time, ie lights."
 
Thanks JB I ORDER A RECTIFIER

Thanks JB I ORDER A RECTIFIER THOUGH MARINE ENGINE. HOPE THAT SOLVES THE PROBLEM.WHAT DOES THE RECTIFIER DO?. IS IT LIKE A VOLTAGE REG? THANKS JB AND GRAHAM. HAVE AGOOD DAY.....
 
"A rectifier simply changes th

"A rectifier simply changes the AC produced by the (charge coils) in the stator to DC - it isn't regulated - the battery acts as the regulator in that setup, where a regulator will convert it AND keep the output at a more stable/constant voltage."
 
thanks Graham. what keeps the

thanks Graham. what keeps the batt from over charging? so my setup by changing rectifier will lower the voltage to 13 or 14 volts and should be ok. thanks for all your HELP.
 
If the charge stator and recti

If the charge stator and rectifier are working properly they will generally only push out between 13-14 volts and a Marine battery can take the "slightly wild" un-regulated voltage (which is why it's not wise to try and run a car battery etc in a boat)...
 
i need parts for 40m S002412 c

i need parts for 40m S002412 can anyone help it runs but sluggish and i need to run more fuel through due to setting up a few yrs w/fluids but i need the yr and possibly where to get the replacements wanting to do a complete over haul of the fuel system and make sure my outboard will charge my battery ty for an help
 
"Troy, believe you have a Yama

"Troy, believe you have a Yamaha built Mariner there.

If the part of the serial that you left out is 6E9 then it's a 1982 "C" model, twin carb.

Any Merc dealer still stocks (or can get) maintenance parts for this model but prepare to open your wallet quite wide.

A carb kit for this retails for a couple bucks short of $200 (but at least it will do both carbs), with a fuel pump assembly coming in at about 75 bucks...."
 
up date. changed rectifier bou

up date. changed rectifier bought new mer batt. and steel charging 16 + volts. what should i check next? thanks for any input arcrat
 
"Let it go.<[img]"http://www.m

"Let it go.
happy.gif
Are you checking it on a fully charged battery and a calibrated gauge."
 
I have agauge on the dash at h

I have agauge on the dash at high rpm it pegs the gauge at 16+ volts and yes afully charge batt. thanks for your help JB ARCRAT
 
"I have been running lights,ra

"I have been running lights,radio fish finder, and steel charging max maybe the gauge is bad? thanks again JB .------arcrat"
 
NO CAR BATT.'S
NO CAR BA

NO CAR BATT.'S
NO CAR BATT.'S
NO CAR BATT.'S
NO CAR BATT.'S
NO CAR BATT.'S
NO CAR BATT.'S
NO CAR BATT.'S
NO CAR BATT.'S

1987 engine does not always have a regulator when generic rectifier was on there. It's only a 9 amp. That was optional. The batts are suppossed to handle it. Put 2 sea volt batts on a BIG RED SWITCH.
 
thanks bandit... i have a new

thanks bandit... i have a new marine batt..do you think someone put the wrong stator in?..maybe a 16v in... what is a seavolt batt? i havent changed anything but the rectifier... thank you very much...
 
"oh seavolt is just "slang

"oh seavolt is just "slang term" for marine batt.
Anyway, the 16 amp stator will keep breaking rectifiers if someone does that.

Your sure your gauge is accurate? The unregulated system is a PITA, because a loose lug on the battery might also do that. The alterntor charges backwards through the battery cables so all those connections need to be solid on both ends. And the cables are not turning green inside from the years of corrosion. You could see 16 volts if any of the connetions are weak."
 
ok my fish finder has a volt m

ok my fish finder has a volt meter thats reading 17volts so the gauge is pretty close. my batt post are clean +tigth. ill check the cables in the morning. thank you so much....Bandit.....arcrat psdo you mean a swith between the batteres?
 
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