Running an errand in the car yesterday and then was going to get gas to go to "Cruise the Gut"  On way to gas station, car loses power all of a sudden (no bang or anything like that).  Push the clutch in and it dies.  Tried to restart while rolling and the starter almost immediately started dragging down, like a dying battery.  Pulled over and tried to start again - same thing.  Does not require much cranking to completely exhaust the battery.  I got it to run very briefly five minutes later, but nothing after that.  Had it towed home (thank goodness for Roadside Assistance on our car insurance).  Put a charger on it overnight and this morning the light was green.  But no action.  Starter turned the motor over a few times but the battery quickly died until I was just getting solenoid click.  The interior lights drag way down while trying to start and battery voltage currently shows at 11.6v.  

replace the battery

Dave, I think you may have a bad battery, as well as possibly an alternator that isn't keeping the battery fully charged. The ignition needs at least 11v to fire. You're showing 11.6 at rest...what does it do when you crank it? Prolly going down to below 9v or less. Get a known good battery connected and see what happens. If it starts, then check charging voltage.
A bad/corroded connection somewhere could cause similar symptoms, so be sure the check the ground under the battery box(on the frame), as well as the ground from the frame to the engine mount by the starter. I doubt this is anything other than electrical...your engine is safe.

Whew - what a relief.  I was pretty sure battery, too, especially after seeing the 11.6 volts, but it just seemed weird since it happened all of a sudden.  I'm used to battery failures that show up when you want to start it cold or after a bunch of short trips where the starter spins more slowly each time.  Or alternator failures that work pretty much the same way, although the engine will eventually cease to run when there's not enough juice to fire the ignition.  So it seems like something catastrophic in one or the other, possibly the one causing the other to fail?  Or can a battery have a sudden internal fault that will siphon enough juice away from the rest of the electrical system such that the engine won't run?  

the old days are gone  used to be we could  a battery  going charging and stuff  not todays batterys  one day the work next they don't,major problem in modern vehicle,may cars just need battery,new car need 13.2 volts to start and keep computer[modules] up to date,just replace them  then check your alt and grounds   I doesn't make a differnest how old or new.dwa

Chances are good that it's a bad battery.  Batteries die in the heat more often than in the cold.  It probably has an internal short.  Pull it out and have it tested, or drop another one in as a test, and see what it does.   Don't just hook up jumper cables.   A shorted battery will drag down a good one, and the car still likely not start.

Yep, battery in my wife's Jeep died 1 hour before leaving for the 2015 Gathering, hot muggy day.

Gotta love Costco - full replacement cost for a new Interstate battery, no questions asked. Old one was only 2 years and some change old. So got a new battery, but I'm still mystified and a little concerned about the suddenness of the failure. And bad enough that it would cause the engine to stop running. I didn't hear or smell anything unusual and the battery is only two feet from my head when I'm in the driver's seat. Should I bring the alternator in to a parts house and have it tested before I try to start this thing?

Wouldn't hurt to have the alternator tested.... batteries can all of a sudden go belly up, and Ken is probably correct in thinking a bad cell in the battery.  Each cell in a battery puts out about 2.2 volts, fully charged battery is around 12.6 to 12.8 volts.  The alternator should be putting out around 13-14 volts... Costco does have a pretty good warranty for their(our) batteries(I work for Interstate Batteries).... we see a lot of 'good' batteries in their core pile that we pick up, so they really don't inspect they battery all that well that I've seen.(heck if I didn't already work for a battery company I would join Costco and buy a battery from them, their price is hard to beat)  Hopefully it is just a battery issue and not something deeper. If you have a voltmeter that you can use at the battery while the car is running you can do a preliminary check to make sure you alternator is at least putting out voltage. :) 

Well got it running tonight, but this is weird.  Put the new battery in and engine turned over fast, but no action.  Hmmmm.  Took the air cleaner off and it looked pretty dry in there and no fuel came out of the jets when I pushed the throttle.  Put 2 gallons in the tank and poured a little down the carb and it fired right up.  Well, in my original post I mentioned I was heading to get gas - I was going there for a reason.  If the starter had turned the engine over normally after it quit I would have known right away that I had run out of gas.  But how could I have the simultaneous battery problem??  It's not like I cranked on it for a long time to try to start it - it dragged down immediately.  Guess I'll just chalk it up to coincidence.