...I have money in the budget for exactly this kind of thing, but the problem is me being awake when there's daylight and the auto parts stores are open.
Shit: if I leave RIGHT NOW I can still make it.
Not quite $100 later, the Jeep has a new battery from Advance in it; and it's even an exact fit. Usually when I get a new battery the size is off, but this one slipped right into the insulating sleeve from the OEM battery and fits perfectly in place.
I let the guy from the store install it. Heh. But I could have done it faster given a crescent wrench and socket wrench with a 1/2" socket; he spent more time trying to figure out what size were the nuts on the terminal clamps than I would have just unbolting them with a crescent wrench. But, oh well.
The important thing is, the Jeep cranked faster than it has ever cranked in the time I've owned it. Big change from the rurr...rup. Rurr...rurr...vroom that it's been doing since it got cold; but it's never cranked very fast even in summer weather.
To be honest, if I had simply gotten hold of some sulfuric acid, I probably could have changed the electrolyte and given the thing a good charge, and had it be good for years longer--but disposing of the spent electrolyte is a royal pain, and where can a regular guy pick up a liter of sulfuric acid in this post-9/11 world? (I know, some hardware stores and auto supply shops sell battery electrolyte. I'm just sayin'.)
The battery gauge reads higher than it ever has. Since that's a voltmeter I can infer that the old battery was no longer producing the voltage it should have; it could still generate plenty of current (the fact that it would crank over dead slow is also an indication) but it's obvious that none of the plates were shorted. Heck, I might have been able to add some distilled water and gotten another year out of it.
But why bother? The damn thing was original equipment, making it ten years old. A dead battery leaves you stranded, and trying to stretch out the life of a dying battery does not save you any money in the long run. You'll still have to buy a new battery; and the prices will probably be higher next year. (And if you get stranded, you either prevail upon someone to help you, or call a tow truck for a jump. Either way, you're freezing outside until you get help.)
Fuck it. This way, I know the battery is good; and if it fails any time in the next two years I get a totally free replacement.