Too much voltage?

[Outakash]

After installing a new rectifier on my 1987 48ESL I fired it up & checked the voltage output. At idle it is bbetween 12.9 & 13.1. I throttled up and it started to climb. When it got to 15 volts I throttled back to i idle and shut it off. Doing this in the yard on the hose. Battery reads 12 volts with nothing connected but has been sitting for a month in the shed. Is this normal? Can I run it in the water or will this over charge the battery and cause problems?

 

[papyson]

a fully charged battery should read 12.7 volts..on these unregulated charging systems the voltage will go as high as 17volts and i have saw them peg a 17volt meter....a regulator will normally not allow it above 14.8....the problem is engine design vs modern batteries...the owners manual for that engine calls for a battery that you cannot even find in stores today...much smaller and weaker....the sealed and gell batteries do not have an internal discharge capability(lightning) as the old ones do if they are overcharged and will take whatever the charging system puts out...i have saw marine batteries do the same thing...the first indication that your rectifier is starting to go will be your tach cutting up...reading to high or all over the place....then your voltmeter will be reading high etc...then one day you got no tach and the meter reads just battery output...the rectifier is shot again..a new rectifier may last a week or 3 years..no telling...the good thing is i never knew of this failure to take out the stator winding....the fix is to add a regulator or use the cheapest lowest amp hour battery you can find..or add a permanent additional load...i dont like that option because it will be forgotten and we end up with dead batteries dont we....