My '90 244DL w/ 125K just gave up today. The "battery" idiot light had been coming on for a few seconds upon first starting up this last week. The light would go out and not reappear until the next time starting the car up. Today, again this happened, a few minutes later as I was driving, the stereo went out and then the car stopped. I tried a jump start, but it would only stay running a few minutes then died. I tried the jump start again, same thing happened. I'm thinking since the battery is only 6 months old, it may be my voltage regulator or alternator acting up? Any suggestions? A friend said that depending on where you purchase batteries, it could of been an old battery just sitting on the shelves or a reconditioned one that didn't have a whole lot of charged cells to begin with. Thanks in advance!
'64 1800S, '90 244DL

Since you first noticed the charging/alternator idiot light (actually not a "battery" warning light, since it isn't about battery voltage or condition, but about the charging system), I'd suggest that there's a problem with the charging circuit: the wire connections, the diode (rectifier) pack and voltage regulator.

That it ran for a brief while after a battery "jump start" means: the battery voltage had first dropped below what is required for the engine to run (it ran down because it wasn't being charged), then when you got a boost it ran for a while until the recharge from that boost was depleted, and then the engine quit again for the same reason.

Have you got a cheap VOM to check your battery voltage: don't blame your battery right away (despite that your friend told you something with a grain of truth) -- that idiot light was telling you the more important information, that your charging system, not the battery, is likely the culprit.

Good luck.

my first guess would be voltage regulator if your alternator belts are tight enough.