I agree with using my voltmeter, but I wanted to get broad (hehe) input on a broad (hehe) problem.
And, I agree with trying to figure out the cause of the failure. It was about a 5y old battery, had to get it boosted a couple of times over the last couple of summers because the doors were off, the door fuse was pulled and I installed high intensity headlights and left them on (dead in hours), had been sitting idle for two weeks over Xmas (underground parking, so freezing is not possible) and had been sitting for a week earlier for a week. The first boost worked, but second didn't (maybe a bad connection).
Ultimately, I think that it was a doomed battery. But, I'll be testing with a voltmeter every couple of days for a while idle and running to look for any significant change in results that might lead to wiring or the alternator. Plus, I'm gonna give the engine and undercarriage a good stray to get rid of the salt and crap. Clean her up because she's dirty...