Originally Posted by Martian
Since this happened, everybody I talk to has either had a gel battery fail, or has ridden with someone who's gel battery just suddenly quit. My suggestion for anybody who has one is to keep it fresh. If I'm taking off on a long ride and the battery is more than 2 years old, I'm replacing it before I leave. The battery was a Panasonic, BTW. Not that it makes any difference.
This is why I'm not a fan of Gel batteries. When they go, they go suddenly. And there is no way to keep a check on the status of individual cells. At least a slosh, lead-acid battery usually gives warning when it it about to expire and the state of each cell can be easily checked with a readily-available hydrometer. Typically when the battery is nearing the end of it's service life one or more cells will start to show less charge than the others.
A good battery and an on-board voltmeter make for confident travelling.