Feel like I should know what's wrong...HELP!!
 

So a few mornings ago I jump in my Dakota and turned the key. It wouldn't start. The dash lights flicker like crazy and it clicks fast enough to be a machine gun but won't turn over at all. I used a battery charger and after about 30 minutes it turns over and I think all is good. Maybe just a dead battery. Well after driving for a day my truck decides to start dying on me at slow idle speeds of 10 miles or less and usually when turning. I think it might be the alternator or a bad connection to the battery. I clean the terminals and add water to the battery. Seems to work a little better. Then about another day of driving and it starts dying on me again driving the same idle speeds or turning slowly into a driveway or parking lot. When it dies however it usually starts right back up or might flash and click at me but eventually turns over after a few pumps on the gas. Tonight as I was pulling into my driveway the red battery dash light turns on for a few seconds then turns back off. I parked my truck, turned it off like normal. Now when I just went to go somewhere it's completely dead. I used the battery charger for another half hour and it will flash the dash lights and click at me but won't turn over. Is this a problem of a dead battery, an alternator or possibly something else?

Yes, it is likely the battery or the alternator, but we can't tell from here! These things are sticklers for a constant voltage, high enough to run all of the electronic trickery!

Charge it up again (over night) and drive it to one of your parts stores, where they will happily test your battery in hopes of selling you a new one.

If it isn't the battery, it is likely the charging circuit.

My guess would be a failed battery. A recharged battery that's in good shape will have more than enough capability to turn the engine over and get it started - the fact that it doesn't turn over tells me that the battery won't hold enough charge.

Battery.

Quite possible both a bad battery and a weak alternator. Alternator should be able to keep up with the truck's electrical needs even with a flaky battery under the hood.

As Northgator8 stated, take it up and have both tested. You might also check the fuseable link (Bit of blue? wire) between the alternator and the fuse block there under the hood. If that has failed, it'll keep the alternator from charging the battery.

If the battery doesn't have the power to turn the engine over, even an excellent alternator won't help. Once the engine is running, the alternator should be able to supply all the engine needs and replenish what the battery lost in the starting process.

The chatter you get when you turn on the key is the solenoid - it isn't receiving enough power to engage. Borrow a known-good battery and try it - this is not rocket science.

Thanks for all the help. Turns out the battery was dead. It was able to hold enough charge to turn the engine over but that was about it. Then it finally died. Just bought a new one and now my truck starts up with no problem but is still dying on me.

My A/C cuts out when I let off the gas and the RPM's bounce around like crazy once I slow down and they reach under 1,000. I'm guessing it was a mix of both the alternator and the battery. I'll check the fuseable link tomorrow when it's light outside.

Will having a bad alternator ruin my battery? If it's not caught in time?

A bad alternator can do damage to a battery, it depends what's wrong with the alternator but a bad charging circuit will keep draining the battery, so you'd need to keep recharging the battery from an external source.

I'd suggest taking the truck to an auto parts supplier that will perform an alternator test as well as check for diagnostic codes - I'm sure you'll have some codes showing. Any check-engine-light? There are quite a few places that will perform these tests for free - they sell more parts that way.

I do have a code showing. It's P0850 park/neutral switch performance. I didn't think that this would have anything to do with the battery charging. I'll swing it by Pep-Boys and see if they can check the alternator for me.