I have a series of ponderings leading to a question or two.
I bought myself an Asus Eee 900A (it is a strange, lesser-known model; apparently it is one Best Buy sold for some time) and its battery life right now is something like 2.5 or 3 hours…with the wifi turned off, screen brightness turned down, and not doing anything to tax the processor. When I am actually using the machine, the battery life drops to like 1.5 hours. That’s not long enough for a full class for me. Therefore I am trying to extend it.
My original thought was to take 8 D cells, put them in series, and that would equal 12 volts. Except it might not. And I really don’t want to burn up my Eee. I would put a regulator in there, except the highest-capacity 12v regulator I know of has a 1-amp maximum, and my Eee wants 3. I know that’s a maximum, but if I don’t plan for it, I will definitely reach it.
I’m not sure what to do; any advice anyone could offer would be great.
I don’t know about the little Eee for sure, but at least with my laptops, you can’t just replace the original battery. There are too many connections the battery feeds. I assume then that you want to plug the battery into the adapter’s plug. It is still not a good idea to run a laptop strait from a battery. The power supplies for laptops create smooth uninterrupted power. There will be no glitches and the voltage will be constant. Plugging in a few batteries will not provide the smooth power nor the constant voltage the laptop needs. The short way to say all this is that you really aren’t going to just be able to get something off the shelf and make it work. Just a question. Why not bring the power adapter with you to class and sit near an outlet? Maybe an extension cord?
Jacob,
I am guessing you wish to avail yourself of the external power connector for this application. D is correct in that the external power supply is regulated. The internal power supply running off the battery is a separate power supply in most cases. It uses a form of boost/buck regulator to keep the various supplies at specification right down to the complete discharge of the battery. You could go to C cells and use 10 or 11 and a three terminal regulator for the 12 volt supply. A high current LM317 will do the job and supply the current but you will need to get rid of some heat on the regulator. Some of the sub C nicads would also do a nice job in this application. The drawback is the weight of the package. There are a variety of boost/buck regulators out there but cost and complexity do factor into the equation. As far as cost vs size/weight, it is almost better all around to find a cheap replacement battery for the internal battery.
Apc and a few other companies have made in the past a battery the size of a 14" laptop and it comes with 20 different plugs for laptops. I own one that runs my 15" laptop for about 4.5-5 hours before using the battery on the laptop. There is also a smaller one capable of about 2 hours. I bought mine from Circuit City before they closed for about half price but you should be able to buy them elsewhere for around $100-120.