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Charging system voltage high (f25MLH)

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Stickyskilet

New member
I bought a fishing boat last year with an f25mlh65w outboard. The boat had an onboard charger which recently went kaput. I took the charger out, and wired the output from the outboard to the common post on the 1/2/both switch, after having heard that it was bad to not have the charging system wired to a battery.


My problem is that the voltage being delivered to the batteries, (which test at 12.6v isolated) through the rectifier is too high. (15.5v @ idle and 15.75v @half throttle)


I’ve also been told elsewhere that the 2005 f25mlh 65w did not come with a rectifier... but it did come with the leads from the stator to connect one if you wanted to charge a house battery.
I’d like to know if the rectifier(non OEM) that has been put in by the previous owner, can simply be removed, and the two leads from the lightning coil be capped and tucked away?.. or would they have to be dealt with in some other way?


I’d also welcome any thoughts about whether the 15-16v while the engine is runnning is a major problem... and if so, any suggestions about ways to get that down.


Thanks



 
15v isn't that bad. Is that at idle? What is it at wot? You need a rectifier to get dc voltage and a regulator to get 14v you can't just tuck away the wires unless your not going to have a charging system..
 
Stickyskilet said:
I bought a fishing boat last year with an f25mlh65w outboard. The boat had an onboard charger which recently went kaput. I took the charger out, and wired the output from the outboard to the common post on the 1/2/both switch, after having heard that it was bad to not have the charging system wired to a battery. Crap information.


My problem is that the voltage being delivered to the batteries, (which test at 12.6v isolated) through the rectifier is too high. (15.5v @ idle and 15.75v @half throttle)

What rectifier? The F25MSH/F25MLH does not have a rectifier or rectifier/regulator. Since when is 15.v volts too high?


I’ve also been told elsewhere that the 2005 f25mlh 65w did not come with a rectifier... that is correct but it did come with the leads from the stator to connect one if you wanted to charge a house battery. maybe not
I’d like to know if the rectifier(non OEM) that has been put in by the previous owner, can simply be removed, yes and the two leads from the lightning coil be capped and tucked away? yes but then there will be no electrical output from the motor.. or would they have to be dealt with in some other way?


I’d also welcome any thoughts about whether the 15-16v while the engine is runnning is a major problem not a problem at all... and if so, any suggestions about ways to get that down.


Thanks
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Comments above
 
mechanicman said:
15v isn't that bad. Is that at idle? What is it at wot? You need a rectifier to get dc voltage and a regulator to get 14v you can't just tuck away the wires unless your not going to have a charging system..
Click to expand...

thanks for the reply... I didn’t test at WOT... but the 15.5 was idle, and the 15.75 was about half throttle... would lead me to believe it’d climb to around 16 at wot.

to be clear... I’m not hung up on having the charging system at all. I’d be just as happy to disconnect the rectifier and leads altogether if it’s safe to do so.
 
Stickyskilet said:
thanks for the reply... I didn’t test at WOT... but the 15.5 was idle, and the 15.75 was about half throttle... would lead me to believe it’d climb to around 16 at wot.

to be clear... I’m not hung up on having the charging system at all. I’d be just as happy to disconnect the rectifier and leads altogether if it’s safe to do so.[/QUOTE

You can do that. The motor came from the factory with the rectifier. You are just returning it to its original configuration.
Click to expand...
 
Jinsoo said:
I think 15.5v is too high.

may be that rectifier is bad...

just normal 13.0~14 v @ idle.

rectifier inspection need a DVA tools.
Click to expand...

Rectifiers don't adjust or control voltage. Voltage from a rectifier is based on the AC voltage from the lighting coils to the rectifier.

Regulators control the voltage. In many small Yams it is not uncommon for the regulator voltage to be 16 ~ 17 volts. Completely normal.
 
Thanks everybody for chiming in... I decided to remove the rectifier, and just go without the charging system.
Ive made sure that the two leads from the lightning coil are well capped.
 
Mikey N.C. said:
I'm I missing something , doesn't stator generate AC at 400 to 700, and rectifier changes it to. Dc ?
Click to expand...

The lighting coil does produce AC voltage but not as high as you indicate. The SM shows minimum voltage as being 26 peak AC volts at 1500 RPM and 60 peak AC volts at 3500 RPM. With the lighting coil unloaded. That is, it is not connected to the rectifier/regulator.
 
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