I just bought a new battery about 3-4 months ago for my 2008 Honda Shadow areo 750, and I have to charge my bike everytime I put it away over night. When I try to turn it on the lights are one, and seem bright, but when I turn it over it dies our fast and don't have enough juice.
I brought it up with other mechanics, this where the new battery can in about 3-4 months ago and now I'm going to get the battery low tested. I tested the battery with a multimeter, and it went to 12.34. I think there is a short in a wire, it feels like I'm grounding out somewhere...don't get me worng, I'm not a machanic, but this happened to my in one of my old cars.
Have your battery charged and load tested. If the battery tests out okay
then check the charging voltage on the battery terminals at 2000 rpm.
It should be at least 14 volts DC.
If that all tests okay then remove the negative battery
cable and connect a meter or light between the
neg cable end and the battery neg post to see if something is draining
If the light comes on or the meter has a drain reading then
try popping fuses until the drain stops. This will
tell you what circuit is draining if any.
Sometimes if you ride infrequently the battery may need to
have a small 1 AH trickle charger on it.
If the charging system is not working then get back to me on that.