Checking a Rectifier What am I reading?

dagersh · Post by **dagersh** » Tue Oct 30, 2012 4:54 pm

Hi Guys,

Quick question: I have replaced my OEM Rectifier with a new Radio Shack one. At 3.3K RPM (Full advance), I am reading around 6.5 to 6.7 Volts on both wires coming off the Magneto, and 12.7 V off the Battery + lead, and a nice clean ground on the ground wire.

The bike is running great, and the battery is keeping charge. I am just curious if you add the 2 readings off the magneto wires, and come up with the power being supplied to the battery to keep charge.

Thanks guys!

jensey · Post by **jensey** » Wed Oct 31, 2012 1:06 am

Hi,

You measured a voltage, but between which wires ?
How exactly did you measure the voltage of the magneto ?
Was the meter set to DC or AC ? Did you measure with a load, or open contacts ?

Really, you have to be a little more specific, otherwise I can't interpret the results.

In the link below is shown how the generator is wired, I suggest to read it for your understanding.

http://www.hondatwins.net/forum/viewtop ... =53&t=7534

Jensen

dagersh · Post by **dagersh** » Wed Oct 31, 2012 2:54 pm

Jensey,

Thankls for the reply. Let me see if I can clear it up a bit...

Right now I am working on a '64 CA95 which I have converted to 12V.

At the rectifier, I have a red wire coming from the battery and into the 12v + on the rectifier.

I then have a Green/Yellow wire coming from the generator as well as a Brown wire also coming from the generator.

Finally, I have a - Ground wire from the rectifier to Negative terminal on the battery.

The 6.7 volts was read off my multimeter, set on the 200 VDC setting, between the Green/Yellow wire and the Negative Ground. The same for the Brown wire.

Again, the 6.7 was read at engine RPM above 3500. I don't know if this represents a load or not....

I have read through that post previously - but I am not quite able to get the gist of it...

Gersh

jensey · Post by **jensey** » Wed Oct 31, 2012 3:28 pm

Hi,

When measuring wires between generator and rectifier you should measure AC (meter on AC), and only between wires coming from the generator, meaning measuring between the green/yellow and brown wire. A generator on a Honda doesn't have a reference to ground.

If you measure one of those wires compared to ground you measure the 1/2 bridge voltage. being around 6 / 7 V.

When measuring wires between rectifier and battery, you should measure DC, between the red wire and ground or neg at the battery, and you will measure as stated around 12 V.

In fact you measure the battery voltage plus the superimposed voltage from the rectifier.

Jensen

dagersh · Post by **dagersh** » Fri Nov 02, 2012 3:26 pm

Jensey,

Thanks for the help! That actually makes sense!

So, on both the CA95 and the CB77, measuring on the Generator wires I get 13 and change at idle, and over 16 and change above 3500RPM.

My multimeter is set at 200VAC for these readings.

New question, should I see a major change at idle with the headlight on? Definitely no change at 3500RPM.

Thanks!!!!

Gersh

jensey · Post by **jensey** » Sat Nov 03, 2012 2:21 am

Hi,

Normally not, but what do you call a big difference ?
For these kind of measurements I measure the current, it gives a realistic answer.

Measuring and interpreting currents is more difficult,

Jensen