Drove home tonight from a dinner and noticed the dash lights were dimmer than normal. Got home and left 2 hours later to return a movie a few minutes away and after dropping it couldn't start the car. Not enough juice to crank. Got a jump and drove home and as soon as I got home tried to start again to check it and no start again, won't turn over again.

I put in a new battery less than 2 years ago. New alternator about just over a year ago after the previously new one failed after a few months when pulley seized. I checked the battery by popping the tops off and all cells covered with water but one cell has a slight build up of white stuff starting on the side(under the water). Charging the battery now and it read 8V when I hooked up the charger and started charging.

I'm guessing the alternator is not charging. Can an autoparts store test the alternator easily if I take it off and bring it in?

One more thing, when I try to start the car the defroster automatically turns on even though car wont turn over.

Get a multimeter and check the voltage across the battery when the engine is running. It should show 13.5 - 15 volts if the alternator is working, a low reading indicates not charging properly, a higher reading indicates overcharging - a faulty regulator.
The defroster coming on sounds like a faulty relay, probably a seperate fault to your charging issues.
Have any warning lights come on? or not come on as in the charge warning light should be lit before the engine starts and go out when it is running.
Hope this helps.
Roger.

Just tested the alternator with a multimeter as per youtube video - Battery reads 12.6 - 12.8V when car off and reads around 12-12.6V when car running, 11.9 when defrost and lights on, so looks like its a bad alternator. Alternator seems also to have a odd smell from it like electrical burning smell but no smoke or anything like that.

Thanks for the info, you replied while I was writing my last post! No warning lights, charging light is on b4 engine starts and goes out when running.

I guess its pretty clear its a bad alternator then.

Glad to hear you pinned down the problem, always happy to try to help.