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F40TLRC charge voltage

15PBoat

New member
Bought this boat/motor about 4 years ago. Charging seemed OK, Tach worked.

Recently had burned out Rectifier/Regulator. Although it had lost Tach signal output some time back, when battery got low I found the Negative terminal loose which probably finished off the Regulator burning out (actually burned through the back cover black sealant).

Considering Yamaha OEM R/R was $200+, I bought a good used OEM R/R. Installed and when test running on water hose with battery charged to 12.7 vdc. When started the charging voltage was 14.4 and did not fall back to 12+ as would expected after running at Hi-idle a few minutes. Have not yet had it on the lake to give longer higher RPM run to see about charge voltage.

My SELOC Manual says the R/R output should be 14.5 volts, but that at 12.5 volts battery, charging should drop back.

Read on another post about a Yam F60 which routinely was at 14.5 volts.

My greater concern is if it continues charging at 14 volt beyond a short time enough to bring battery back to full 12.5, it will ruin the battery.

Anyone have any insight on this?
 
Nominal output of the R/R is 14.5 volts. That is the voltage that is normally seen at the battery when the battery is fully charged with the motor running.

Millions of Yamaha's (and other brands) are applying 14.5 volts to fully charged batteries for hours and hours at a time with no ill effects.
 
Thanks Boscoe.

Its good to be assured that the good used R/R I saved a ton on turned out to be a good buy.

And am no longer worried about cookin my battery.
 
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