As My old netbook becomes more and more addictied to its power adapter and finally can't live without it anymore, i thought it would be time to replace it. But shocking: this rare model in this pretty white color cost's more than 60€. And as a follower of the self repair manifesto and knowing that the produces uses also only standard parts i decided to replace the cells. This costs about 10 bucks, an hour of work, minutes on ebay and a few days waiting for shipping.
The last working state of the pack is long ago, so the OS has no idea of whats happening in there.
After the replacing it seems i could work about half time longer than with the fresh original part.
Step 1: Preparation
You need standard soldering tools and skills. A cutterknife in good condition will also very helpful. Some cables would be helpful when you brake the soldertails.
Step 2: Open the Case
Most cases are friction welded or glued with heat. You should see somewhere around the case a line. Follow it whith the knife all around. You should feel if the knife goes through. The long accu packs are not reinforced in the middle since they are mecanical supportet through the cells. If you done the opening itself should not need much force. Be Carefull in the corners to not to break something. Correct cutting should prevent any problems. Be also aware that the cells could be glued to both sides. In this case check that all sides are cutted and then you need some force. Thats it. This was the hard part of the whole project.
Step 3: Changing the Cells
Find out what type of cell is used, there are only a few li-ion cell specifications out there. If nothing is printed on, just check the measurements. You should check them twice also before ordering. You should prefer cells with allready mounted soldering tails. The ones i've got hint theirs behind the protection circuit and the caps. If you can't find such versions, you have to solder cable connections between the cells. make sure that the space is big enough to fit in the case.
The Direction of the cells should be concluded from context (cable color, prints on the cell or pcb).
Just in case if someone asks: the cells are mounted this way:
red> (+ -] (+ -] (+ -] <black
and between the cells goes some wire to the circuit board for monitoring and protection.
In modern computers you should find normally li-ion cells. It should be printed on the label. The supply voltage should be a multiple of 3.7Vdc, so you also have a hint of how many cells you find inside.
Put everthing together. Just a little warning: check the wiring twice, check possible shortenings at the cells, from the cells and the board. If you want to be sure, measure the voltage between both ends. Since a li-ion accu should never be empty the targeted voltage of 3.7 times number of cells is nearly reached. If not, something went horrible wrong.
Disclaimer: If something went wrong, it was your fault!
WARNING: loaded and shortet li-ion cells tend to explode from time to time. Also not my fault, even not my Idea.
Finally, my device is offline (off-cord), wardriving through the neigborhood, annoying apple-fanboys as wifi-jammer again, it runs hours and hours around with no cable and even can left the icu with no doctor around!
All in all a good solution on nearly any cell driven devices, also drills, flashlights etc. where no spareparts are available anymore. And much more cheaper than original spare parts!