battery or alternator?

This morning on the way to work at a red light my car just turned off. I had no power to anything. I couldn't turn on the emergency lights. So basically full power loss.

I have a dry cell battery on my car and I don't know too much about them. It's been on there for maybe 5 years. The connectors look good, no buildup and no connectivity issues from what I can see.

Once the car was towed back to the apartment the power came back on to the car and it would start. I don't know what would cause this other than an alternator that has gone bad.

Any hints ?
What a way to start a Monday...

http://photos21.flickr.com/34222971_05de2a6905_m.jpg

Really stinks doesn't it!!! I would check all connections to the battery and the ground to the engine block. If your battery is 5 years old you need to replace it anyway since it has probably outlived its usefulness. Corroded or loose battery terminals or grounds can cause a problem like you indicated especially since there was no power whatsoever and the fact that it started later after being towed. So the connections would be where I would start.

I had the same problem (total loss of power) but even next day the car would not start. It was the battery. Replaced it and the car is working fine.

.... I know this sounds completely out of the ball park, but could the bushings/bearings in the alternator be going? And when your car is running (at night) and you accelerate up a hill, does your headlights dim/brighten?
Much luck,
Bill

check the connection on the starter solenoid it may be hard to get at but most likely the cause. This has happened to me on more than a few cars.