Motorcycle Repair: Harley Davidson Sportster 1200 custom, harley davidson sportster 1200, harley davidson sportster

Question
Hi
the battery of my bike lives just 1 months then it dies. I brought the bike to several mechanics but no one has been able to find out what the problem is; only one of them said that it could be the alarm which continue to take energy out of the battery.. but the last time I used the bike for the all day and after 12 ours it died.
Please try to give me an help, even Harley Davidson here in Milan has not been able to find a solution for this problem.

THANKS
Arne

P.S.
Sorry for my English (I am Italian)

Answer
Well Arne, my experience is with older Hondas but I'll tell you what I'd do if the bike was a Honda.  First thing I'd do is check the charging system to make sure it's charging okay.  When you put a volt meter on the positive and negative terminals when the engine is running and revved up to about 2000 rpm, the voltage should read about 13.5-14.0 volts.  If it doesn't the problem is not the battery but the charging system.  The problem could be in the generator, the rectifier or the voltage regulator. The fact that the bike runs down in just a few hours would indicate to me that the rectifier diode may be bad allowing the battery to discharge through the diodes.  If your volt meter has and amp meter on it, disconnect the negative side of the battery and put the volt meter between the negative battery post and the ground cable.  This will tell you how much current is being drawn out of the battery.  You can then start disconnecting circuits until the current drops to near zero.  The last one you disconnect will the the circuit with the leakage. By the way, your English is much better than my Italian.

Regards
Rich