[Avenir]

I was asked this by a coworker and couldn't quite give her a good answer... pardon if it's been posted before...

If she has a powerbook g3 pismo/firewire playing a dvd with no battery (hers is dead) how long could you conceivably run it through the cigarette lighter on an average car (say an older model civic or something) before you drain the car battery? All it'll be doing, like I said, is running a DVD. I suggested turning the car on every now and then to keep the battery going, but what would it be if you just left the engine off?

Any ideas?

[hibbacross]

Just watching a DVD is not going to kill your battery. Like anything you would have to leave it on pretty much all night for it to drain the battery out. I think it takes somewhere around 40mins for the alternator to charge the battery all the way so you would have to leave the car on for while, but like i said it is more than likely not going to kill you battery from just watching a dvd.

[irus]

It depends on the condition of the battery and the power of your voltage inverter. On an older Civic, I'd say you can get about 2-3 hours with a 100-150w inverter. If a battery dies in less than 2 hours, you probably needed a new battery anyway.

Rus

[istallion]

Even Small car batteries can hold >400 watt-hours so if her dead battery was rated for 50 watt-hours and lasted 3 hours for her usage, then fully depleting the car battery would last 24 hours. I don't know how much power is required to crank the car though, so you wouldn't want to let it go that far.

[aehaas]

At a huge half ampere draw a 100 amp hour car battery would last 200 hours or more if fully charged from the start.

aehaas

[Avenir]

Alright, thanks for the replies. I'll let her know today.

[The Godfather]

Originally posted by aehaas:
At a huge half ampere draw a 100 amp hour car battery would last 200 hours or more if fully charged from the start.

aehaas

Half ampere is not that much. My laptop draws ~24 watts... 2 amps from your 12V battery. It would last 50h.