Charging problems

[Janne]

Hi
This summer the battery om my AT-95 started boiling during a tour. I stopped at a workshop in Germany, bought a new battery, measured the voltage at different rpm and everything seamed fine. 250 km later same story, and now the battery was like a ball. Changed battery again but the bike didn´t start. I guess there is a charging-modulator somewhere and that it´s broken. What more damages can this incident have caused? Where shall I start checking?

[matt]

Most likely cause is rectifier failing. See http://www.xrv.org.uk/phpBB2/viewtopic.php?t=2919 thread. My mod is the extra heatsink version. Mine failed at 14,000 miles.

To test, charge the battery (static voltage should measure high 12 / low 13 volts). Switch off the lights, start bike, rev it up a bit (3500 rpm or more). It should now read around 14.5 V. If you switch the lights on and you see it drop just under the battery's static voltage (meaning the battery is being drained) chances of 10 to 1 the regulator / rectifier is dead. Sometimes the charge goes way over 15 volts and into the 20's which can cook your battery.

Some people postpone changing the regulator by disconnecting one of the headlights, which just helps to keep the battery charged, but is not ideal.

Also check fuel pump contacts and first solenoid off battery positive for corroding connections.

At least, these are good starting points, but don't believe all is OK until you have checked it out!

Matt