Is your laptop battery dead?
Is the runtime not long enough to get you through the day?
Do you carry one of those huge external battery packs?
This instructable is intended to show how one may replace the dead li-ion/li-poly cells of a laptop battery and how one may increase the capacity of the battery by adding extra cells.
The reason why adding extra cells to the internal battery is suggested compared to carrying around an external battery pack is that for the same amount of cells in an external pack, the laptop can run significantly longer if those cells were used internally.
Step 1: External Battery Pack? Rip It Apart and Never Think of Using an External Pack Again!
So what's the voltage rating on your internal battery pack?
What's the rating on your power brick?
Lets use my tablet computer as an example.
The battery pack is rated for 3.7v * 3 cells or about 11volts. However, the power brick outputs 20v.
I've bought external battery packs before and have calculated how long it should last using watt hours instead of amp hours. However, that was wrong. The battery pack would need to output 20v in order to power my tablet, thus the battery cells used to increase the voltage does not attribute to the amp hours, which is indicative of how long the battery pack should last. Thus, a difference of 9 volts is significant. That's about 2 li-ion cells wasted just to match the voltage.
Another problem with using external packs is that the laptop would think that it's connected to an outlet, thus is not so weary of watching how much power it drains. The power brick for my tablet outputs 2.5 amps, thus it is possible at times my tablet is drawing 2.5 amps from the external pack. However, the internal batt pack only requires an average of 1 amp per hour.
So what would one do in order to increase the runtime of one's battery pack? Forget the external pack, just add more cells to the internal one.