I just put a new Interstate Battery in my KLR650 the old Interstate Battery lasted 4 years. My 2007 FZ6 is taking a long time to fully charge on the Battery tender. It might be time for new Battery.
My original lasted about 4 years, was replaced with a BikeMaster (I was in a bind while on a road trip), that lasted only a year. Replaced that with the AGM YT-12B-4 from BatteryStuff, more powerful and less expensive than stock, with a 3 year warranty. After a year, no problem at all. Hope it lasts