Increase the capacity (runtime) of your laptop battery.

Step 4 Preparation/setup

Safety preparations

-put sand in can (picture below)
-place fire extinguisher someplace close

Battery preparations

-if you're just replacing your dead cells with new ones, obtain the same number of cells. As for choosing the capacity, bigger is better.
-Note how the cells are connected in series and parallel, and solder your new battery pack the same way.
-NOTE: do not remove dead battery cells from battery pack (explained later on)


-if you're increasing the capacity of battery pack, obtain nth times the number of cells in your battery pack (an original pack of 3 cells can have 6,9,12 cells, etc)
-for every series connection in the original pack, you can add cells in parallel. (a pack with 3 cells in series can accomodate 6 cells (pairs in parallel) in series. That is, two in parallel, and attach those pairs in series, etc) any number of cells in parallel is ok.
-NOTE: once again, do not remove the original cells from the battery pack.


My battery pack below has 3 sets of 4 cells in parallel, which are connected in series. (note: parallel groups are separated as left, middle and right. ) Wires are also connected so that I can solder the new pack to the smart circuit easily.

Comments

[erixpc]

Being off the grid for 8+ hours sounds exciting. Instead of strapping on extra bulk and weight to the laptop battery pack, what do you think of adding a 4 wire pig tail connector (http://www.etrailer.com/Wiring/Spectro/9653P.html) to the existing pack and then connecting that to the DIY external pack with all those li-pos? Would that work? How long does it take to fully charge your 15 cell set-up?

[xeijix]

A few things to note. You can't use any of the old lipo/lion cells. The wire from the battery cells to the laptop battery pack can never be disconnected. (you can probably put in some fail-safes in case it does get disconnected, but it's not something you can make a habit of. Every time you disconnect, you risk screwing up the smart circuit)

Mine takes around 8 hours to charge so I just leave it charging overnight.

[erixpc]

Got it. Don't mix old wth new. All batteries should be new. Got it. External pack to cut down on bulk and weight is fine but don't use the pig tail connector. Solder the cord directly. Thank you.

[xeijix]

Yup exactly. Just one thing to remind you, you shouldn't take out the old cells until you soldered on the new cells, this is because the smart circuit can't be disconnected from a power source. (Just think of where the bad/good guy needs to replace an artifact with a dummy artifact before the pressure switch activates a trap)

[Noblenutria]

Hey Harrison Ford could help me with this instructable.

[Noblenutria]

If your battery is mostly discharged when you start doing surgery on it it wont catch on fire even if you short it.