My OEM battery lasted about 3 years.  I replaced it with a cheepo sears lawn mower battery, which has worked fine for 2 years now.  The vent hose is on the wrong side of the Sears battery, so it took a bit of snaking around to make it work, but it fit fine.

I had to replace the battery on my '02 last year, it was getting weak, showed too much of a voltage drop when cranking. Plus if the bike didn't start right away it wouldn't start unless jumped. The owner of the local mom and pop motorcycle store said two or three years is all that can be expected out of a stock battery. I always thought a cheep trickle charger could be made using a regular light timer and a plugin 12 volt power supply that puts out maybe 1/4 amp. Just set the timer to kick the power supply on for an hour a day. It would keep the battery topped of without burning it out by running a charge into it all day. Just trying to reinvent the wheel as usual

Well, I put the Big Crank in and the bike start right up The old battery had a few cell way-below the low level mark. But the cell at the inspection window show MIN while other hidden cells went low. So we can just rely on that inspection window

Now that I have a sealed battery, no more inspection needed

6 year OEM battery????
My bike wouldn't start today and it seemed to be the battery.  So, hubby and I removed it and found out that one of the plastic yellow caps was broken, and some electrolyte was missing from the first channel.   Yet, it was an OEM battery, so I'm guessing that it is the original battery from 2000.  The bike didn't have many kilometers on it when I bought it in 2005, so maybe that's why it lasted 6 full years!!!  

Anyway, we went to Cdn. Tire and purchased a motormaster bike battery.  Once it's charged up, I will take the bike for a testrun tomorrow.