how long should a battery hold its charge?

New to biking, but was wondering, my SV has a battery thats just over 2 months old, its also got an alarm... how long do you think it should be ok to leave it without riding before there isnt enough juice in the battery to start her up??

The battery should be charged up once a month. With an alarm on it you'd have less time than that, it depends on how much current drain the alarm has.
A battery tender is a great thing to have. If you can't plug one in at the bike then you can take the battery off the bike and put in on charge in the house. Of course then you won't have an alarm on the bike.

Mine has a older battery + alarm and will fail to start after being ignored for a month. I have a jump start pack for such occasions, as the bike is on the street which makes a battey tender tricky!

[embee]

Aftermarket alarms can be notoriously hungry, and bike batteries don't have all that big a capacity so can get drained relatively quickly.

As a very rough guide expect a reasonably serviceable battery to lose between half and one percent per day simply by standing still, the actual service capacity might be only around 75% of the quoted value in real life, and an alarm might take a few milli-amps. You probably need it to be at least half charged in order to start it successfully.

Add these together and you probably can afford to lose around 3-4Ah at most, which at a rough estimate will be something like 4 weeks. (28 days, say 15%=1.5Ah loss due to natural discharge and 700hrs at 2mA = 1.5Ah)

If it doesn't start off fully charged and the drain is greater you might only get a couple of weeks.

Get rid of the alarm and you'll increase the life of the battery no end. Further to that, you'll have far less electrical problems with it too.

I'd also add it depends on the weather conditions as to how long a battery will hold charge for.