Maybe I worry too much, but I always imagine the worst when the GS tips over onto a cylinder head and the electrolyte in the battery starts sloshing around. The vent tube is routed low enough so that any acid that does manage to escape should make it to the ground without splashing on anything metal, but there's always the chance that won't go according to plan. And regular maintenance of the electrolyte level is also necessary to keep the battery in good shape. That's not a big deal, since removing the battery is pretty easy on the GS. But it's just one more thing to screw around with, and there are ways of keeping things simple when it comes to batteries. Frankly I was surprised when I checked the log for the R100GS and found that the BMW battery was almost six years old, as it had given no signs of ageing like slow cranking or unexpectedly going flat. But six years is plenty for any battery, and I'd just as soon replace it in the comfort of my own garage than have to bump start the bike somewhere out on the road until I can find something that would fit. I'd had pretty good luck with a Panasonic sealed battery in the K1200RS, and with Digi-Key's $58 and change price (including shipping), swapping out the wet cell BMW battery for the maintenance free Panasonic was a no brainer. A week after the check went in the mail to Digi-Key, the Panasonic was sitting on the door step. As shown by the part number on the side of the box, the correct battery for the R100GS is an LC-X1228P, the P referring to the terminal type. We want flat lugs with bolt holes, ideally with positive and negative positioned just like the OEM battery, and that's what we get with this Panasonic. They call it a VRLA battery, short for valve-regulated lead-acid, and it uses AGM (Absorbed Glass Mat) technology to eliminate the liquid electrolyte. The LC-X1228P is rated at 28 Amp Hours, just like the original. This battery came with a few California specific stickers adhering to the top surface, each of which left a nasty bit of paper and glue behind when I removed them. A little 3M feathering disk adhesive remover took care of the problem, but it also removed some of the printing from the top of the battery and left a hazy surface in place of the shine every where else. Size wise, the Panasonic is about 5/8" short in the long dimension, and about a half inch taller when measured over the terminals.