So I bought a used GS500e and the guy told me I'm gonna need to get a battery charger for the bike. And sure enough a few days later my battery is dead and the bike won't start. What would be draining the battery while it's off? And how would I fix this? Any info would be helpful. Thanks.

Maybe it's no good?

You might want to avail yourself of the Search function - it's very useful.

A dark current is less common than a charging system failure.  You can hook up a multimeter, start the bike and rev to 3K, and look for a charging voltage.

For charging system testing:
http://www.gstwins.com/forum/viewtopic.php?t=4770

If that checks out, get a new battery.

Ok...

First off.  Are you sure you're leaving the key in the "off" position and not the "park" position?  It's easy to screw up an drain your battery that way.

Second, does the battery have water?  If it's low on water the battery won't hold much of a charge to begin with.

Third, how old is the battery?  As batteries get old they develop lead oxide between the plates.  This conducts electricity.  The result is your battery drains from the inside out.  Look for crud in the bottom of the cells.

Fourth, it's possible the battery may not be charging in the first place.  To test this, start up the bike and connect a voltmeter across the battery terminals.  At idle the meter should read about 12 volts.  At 5,000 RPM the meter should read 13.5 to 15.5 volts if the charging system is working.  This won't tell you how much current it is producing, but will give you an idea of what could be the problem.

Oh, order a Clymer's manual.  Very helpful book to have around.  

Without much info it is more likely to be a knackered battery than a short draining the battery. You could try taking the battery off the bike, or disconnect the positive terminal and if it still drains then it is a faulty  battery, probably the best course of action is to get a cheap charger, it's a good thing to have anyway but be prepared to buy a new battery. If it does not drain then start looking for the short but I suspect you won't have to do that.

admit it, your bike hates you.

Quote from: davipuadmit it, your bike hates you.

Oh dear...he's sober at the moment....

Congrats on the ride. I had the battery croak at 430 kms on my O5. I checked the bike with the multi meter while running it showed that it was charging so I put it on the battery tender and the next day the tender showed it to be fully charged. I checked again with the multi meter but it only showed 10.5 volts. I then took it to work and checked it on the battery checker and sure enough I had a dead cell. It was replaced under warranty . Cost about $40.00 to buy if you had to buy one. [CANIDIAN DOLLARS]  I read on the BRIT site that the 06 gs 500 comes with a maintence free so you may want to check into that .

if the temps are below 40 .. it will lose charge by 1/2 and our batteries dont have that much power in them anycase..

put it on a trickle charger.