Hello all, I've recently encountered a head scratcher. While on my travels this summer my battery has continuously been giving me problems. When i started the trip it was full and happy and kept a charge for about two months. Then it died completely and i bought a new battery thinking the old one had run its course. Unfortunately that new battery died as well so i bought a second new battery thinking that i had perhaps bought a bad battery. Well that new new battery just died too so then i was fairly certain i had an electrical issue and ran some tests. First test was the stator output, which i measured at 24 volts when connected to the two white wires. Looking good. Next i tested the ref/rect output which showed no voltage. Ah ha! A bad reg/rect it seems. So i buy a purportedly working used one on ebay and install it, buy a new battery and do some more tests.

First measurement is a new, unused battery. Reads 13.1v. Next measurement was the output of the new reg/rect and i only see millivolts. Couldnt get a better reading than that. Is this right? When i plugged it back in the connections popped a little with an electric arc. Next measurement was of the battery after a short ride. Bike turned off measurements read 12.9v. With bike on 13.1v. Next measurement was a few days later after a longer ride. With bike off i got 12.7v. Then i took another longer ride and it dropped further down to 12.0v. Took a reading of the battery with the bike running and got 12.0v. Something's not right. Seems like either the new reg/rect is also bad or I'm missing something. I now carry a battery tender on my road trips and charge every night. What else should i be looking for?

Here's a pretty picture from the trip up in California.

Hi Scottie,
Remember the case of the rectifier/regulator is the main ground and it must be securely earthed to the frame and the negative terminal of the battery.

Paint on the frame at the mounting point will stop it from charging.

Sure enough that was the issue. The two mounting points for the regulator rectifier are attachments to the battery box, which is made of plastic. I dont see any metal brackets connecting those mounting threads to the frame anywhere. Perhaps something rattled loose? For now I've run some thick wire between a frame bolt and the regulator rectifier bolt to get me going. Now i get 13.9v with the bike running.