Where would a 12v car battery stack up to a laptop one?

For the purposes of estimating how long an atom d525/motherboard, 2GB ram, and a momentus XT would run for on a fully charged standard 12v car battery.

 

Depends on the capacity of the battery and the power draw from the computer, so the answer you are looking for can vary wildly without knowing these two things.

 

Yeah was just trying to get a rough idea. Was toying with an idea for something like that that would have a devoted car battery as power source.

 

Okay, let's say that an average car battery has 50 amp-hours and averages 12.24V through its discharge cycle. That is 612 watt-hours. Divide that by the average power consumption of the laptop, which would be around 15w I guess for an atom? We would be talking about 40 hours of continuous use before the battery dies. Of course this could vary by a whole lot, like probably from 20 to 60 hours depending on the variables. One thing to note is that car batteries are pretty bad in terms of charge for their weight, but they are very cheap, low-tech, and very reliable.

 

Well, let's put it this way:

A car battery is ~1200 Watt Hours. Average notebook battery is about 48 Watt Hours.

Just make sure you get a deep cycle battery (marine type) not a 'regular' car battery.

Good luck.

 

netbooks probaby consume a bit more than 15w... they come with at least 30w adapters right?

also, you'll want to get an actual car to laptop power inverter (12v > ~19v) bypassing your normal adapter instead of using it together with a car to AC mains inverter (12v > 120v > ~19v) for efficiency.


also, i guess it doesnt matter if you can just start your car.

where you just wondering in case it was possible to completely deplete you car battery in one sitting with a laptop? maybe with a d900

 

Sorry, I seem to have answered here without actually answering the question directly.

If your netbook lasts 5 hours (idle) with its internal battery (lets assume it is a 50 Watt Hour model for the sake of this example), then with a car battery (and an associated car charger to convert the 12V of the car battery to the ~19V the notebook can use) the notebook should be able to run 1200/50=24 times longer or 24*5=120 hours (idle) or 5 days straight.

This is assuming no losses in the converter and a perfect example of a car battery in question. How do we get 1200 Watt Hours? Well, deep cycle (marine) batteries are sold by their Amp Hour Ratings. An average battery will be 100 Amp Hours, so 100 Amps times 12 Volts equals 1200 Watt Hours.

So, adjust the above to fit the actual ratings of the netbook in question and the specific ratings of the battery in question.

Hope I have now given enough information?

Yeah, a car battery packs a lot of energy - be very cautious when handling them.

Cheers!

 

My netbook with SU4100, Intel 4500MHD, 2GB RAM, Kingston 64GB SSD has ~ 13000 mWHr discharge or 13 W/hr