alternator problem

[riverdragon]

i was wondering if any one could tell me if my engine would have a charging system or if i should put the battery chartger on if after every use .
i have a 77 merc 850 long leg on a 15' sangster
thanks

 

[WillyBWright]

Re: alternator problem

It has one. It isn't particularly strong, but it should keep the battery reasonably well charged. An occasional charge might be required due to low usage more than anything else. You might want to test voltage when the motor is running. If the voltage rises with RPMs, it's charging. It's not hard to damage the rectifier. If it isn't charging, that's probably the part needed. They fail from crossed, loose, and corroded battery connections.

 

[riverdragon]

Re: alternator problem

thanks i'll try it
all i need to do now is the link and sink and i think the motors tip top
it does fall flat on its face when i try to sget the shot from start

 

[ricksrster]

Re: alternator problem

You can check the rectifier with an Ohm meter. You should show continuity in one direction only between each yellow/red post and the red post.
I have a 77 850. Where I boat the most, I go long distances. The alternator does keep both my batteries charged.
The volt meter on the dash reads about 15 volts after running a few minutes. I put an isolator on the charging wiring for the two batteries and that cuts my voltage about .75v.

 

[eatropefish]

Re: alternator problem

What should the stator resistance be on 45hp mariner? My rectifier tested bad(naturally) but found no spec on stator. It shows about 0.6 ohms with good DVOM. No short to ground/power on either yellow wire. Also, my newly installed tach is inop. My connections are good and correct. I'm thinking the rectifier is shorting my send signal. I haven't run the engine without the rectifier hooked up for fear of damaging other components.

 

[Laddies]

Re: alternator problem

river dragon, if the engine has a hesitation when accelerated at idle it's usally lean try to open the low speed needles a 1/4 turn

 

[Laddies]

Re: alternator problem

eatropefish, never a good idea to tack on someone elses thread. You ststor tests is fine so either you rectifier is bad or the tack try hookig the tach to the other yellow terminal to see if one side of the rectifier is shorted or just ohm test it

 

[eatropefish]

Re: alternator problem

Sorry riverdragon (et al ) for my poor etiquette.

 

[riverdragon]

Re: alternator problem

no problem i may have done the same thing.

i toke the boat to the "best shop in town " and they set the carbs he told me not to touch the idle jets again
its all in the age of the engine i'm told
but for $5000.00 i can have a great newer one

lol
i think i know how he has stayed in bussiness.

 

[Laddies]

Re: alternator problem

Bet they are dry land and the carbs were adjusted on a hose not in a tank, that always gives a lean off idle condition as there is no back pressure. Any time a dealers starts with the old engine story it's a good time to leave, it proves that he and his staff have no experince and are lost on older engines. We still do a couple of direct reversing engine a year and they are not to old to run properly--Bob