Yamaha 30AE hp rectifier output

Would like an opinion on my rectifier output, to cut a long story short, the red wire from the rectifer, back towards the battery had been disconected by someone in the engines past. After having 2 batteries go flat (one lasted a number of trips last year and didn't go flat until the start of this summer) I investigated and found the battery not charging and then the disconection. I first tested out the lighting coil for resistance and output which was within the tolerances in my service manual, I then tested out the rectifier with an Ohm meter and it checked out good so I connected the red wire back up to the battery. At idle I'm getting around 12.5V which is OK however at cruising speed the Voltage is around 16.3V which seems a tad high. The question is should I get a new rectifer or not?

thanks for any advice!

Just checked with service manual and its actually in spec - for some reason I had the max voltage spec as less than 15V!!

Why would anyone disconnect the rectifier in the first place?

Ideas anyone?

Hi Bass Player.
I'm having the exact same problem myself this Summer. I may actually have had it for a few years but not been aware of it until a new radio that I fitted has an overvoltage alarm which alerted me to it. I since fitted a Voltmeter so I can keep an eye on it and I'm seeing what you are seeing.
My current understanding of the situation is that as long as the battery is taking charge then the Voltage will be maintained at 'normal' levels. When the battery is brought up to full charge and the electrical loads are small, the Voltage will climb. What I've done in that situation is disconnect the wire from the rectifier. I can connect it again when the batery voltage falls to around 12.4 Volts. This obviously isn't a longterm solution. I may build a voltage sensing circuit that will disconnect the rectifier when the battery Voltage reaches and set level and reconnects again when the voltage falls below another set level.
It should be possible to buy such regulators but I havent looked hard enough.

Hi Bass Player.
I'm having the exact same problem myself this Summer. I may actually have had it for a few years but not been aware of it until a new radio that I fitted has an overvoltage alarm which alerted me to it. I since fitted a Voltmeter so I can keep an eye on it and I'm seeing what you are seeing.
My current understanding of the situation is that as long as the battery is taking charge then the Voltage will be maintained at 'normal' levels. When the battery is brought up to full charge and the electrical loads are small, the Voltage will climb. What I've done in that situation is disconnect the wire from the rectifier. I can connect it again when the batery voltage falls to around 12.4 Volts. This obviously isn't a longterm solution. I may build a voltage sensing circuit that will disconnect the rectifier when the battery Voltage reaches and set level and reconnects again when the voltage falls below another set level.
It should be possible to buy such regulators but I havent looked hard enough.

Without getting in to it too much I think a Zener diode set up across the radio + - feed should keep the voltage across the radio steady - though I would think it would be possible to buy something ready made - perhaps try Maplin.co.uk. I suppose it's the very nature of the Lighting Coil charging setup that gives such a large varience of voltage output from the regulator - I suppose that if the same electronics that are available today were available back then at a reasonable price it would have been economic for Yamaha to have a more reliable max output of say 14.6V