hello. im having charging issues too, but im worried that it is over charging rather than under charging. im going to try the tests mentioned in this post, but so far ive tested (as per the clymer manual) the current between the battery +ve and the red lead and got under 1a current at all engine speeds, and also a pretty constant 14v across the battery at all revs (less when the bikes not running). at one point the clymer says the voltage regulator should provide a constant charge at all revs, but it also says the current should vary between 6.3A at 1500rpm and 10A at 5000rpm. ive just fitted a new motobatt battery (the old one lost charge overnight). ive also a vague recollection i may have fitted a new voltage regulator a few years ago. should the voltage across the battery stay around 14v at all revs? any thoughts? cheers. karl

the current should vary between 6.3A at 1500rpm and 10A at 5000rpm

These are maximum amperages, and would only be achieved when the battery is almost flat, or you have hundred watt lamps.

The voltage should be between 13.4v and 14.4v so 14v is a good number.

should the voltage across the battery stay around 14v at all revs?

Yes, that means the voltage regulator is doing it's job of maintaining a constant voltage with a varying load.

yey! thanks for that...

Hi, from a newbie to the forum

I too have a charging issue, have run the checks as described and am getting a nice similarity between X,Y and Z but only 13.3 v from the rectifier/regulator to the battery, please could somebody confirm that this is causing a slow discharge of my battery (quicker when using lights) and that I need to replace the reg/rec.

Many thanks,

Matt

Matt wrote:Hi, from a newbie to the forum

I too have a charging issue, have run the checks as described and am getting a nice similarity between X,Y and Z but only 13.3 v from the rectifier/regulator to the battery, please could somebody confirm that this is causing a slow discharge of my battery (quicker when using lights) and that I need to replace the reg/rec.

Many thanks,

Matt

How did you measure the voltage? No ligths on at idle, or with lights on at idle, or is it 13.3 if you ref it up?

Dirty connectors or a not so great ground between regulator and battery ground might lower your voltage.
Try cleaning the connector, or make a (extra) ground between the housing of the regulator and the battery. If that doesn't change anything, in my view a new regulator is in order.

Hey Ronald, you were spot on with the poor earth diagnosis ,

the 13.3v was measured with the engine running at idle with the lights off, that was on Saturday. We did about 100 miles yesterday and this morning it read 12.8. On closer inspection after reading your reply I noticed that the regulator had only one screw attaching it, one was missing Replaced missing screw, installed extra earth to frame and voila, 14.52v

Thanks again,
Matt