Merc alternator output

[ted655]

I want to install a AGM battery in my boat. After reading up on them, I see that AGMs don't tolerate high charge rates. 14v is the reccomended high end for alt. output. I have no idea what the output of my Merc '02 2 cycle is. Probably not even an alternator on it. More likely some sort of inductive type charging system. Anyone know? Can the rate of charge be set on a 50? Thanks.

 

[Silvertip]

Re: Merc alternator output

Probably 15 amps. It isn't the amperage thats the concern. It's the charging voltage. No -- alternator output is not adjustable. Charging voltage can run anywere from 13 to 14.5 volts on a regulated system depending on engine rpm. If its an unregulated system voltage can go as high as 16.5 or even higher. It has been known to cause sensitive electronics to enter protective shutoff. Don't know if your engine has a regulated or unregulated system.

 

[ted655]

Re: Merc alternator output

I'm back to my question. What type charging system & what is it set at on a Merc 50, 2 cycle 2001 ?<br />Is the adjustment of voltage done proppritary at the factory with solidstate or can it be set in the field?

 

[Silvertip]

Re: Merc alternator output

Neither output voltage or current can be adjusted. Voltage varies depending on engine speed. At idle its about 12.6V as RPM increases it goes higher. Same for current. The charging system consists of magnets inside the flywheel that pass over coils as the flywheel turns. This is basic power generation that has been used for decades on outboards. My reference indicates that engine has a 16 amp alternator but it doesn't say whether or not its regulated. Regulated means its output voltage is limited on the high end at somewhere around 15 volts. What you need to do is have someone measure voltage at the battery at wide open throttle (assuming your boat does not have a voltmeter). If it does have a voltmeter, what does it read at WOT? There's your answer. If its higher than the specs indicate for the new battery you probably shouldn't use it. Lastly -- are you using an AGM battery as a start battery or for a trolling motor, or both?

 

[ted655]

Re: Merc alternator output

No voltmeter, I do have room for one. I will put one in. Starting is the primary use, sometimes we spotlight off it or run a few electronics.<br />Guess I'll look at a voltage limiter of some type as about 1/2 my operations are at WOT or 3/4 wot.