Here's a little tutorial on how to harvest those 18650 batteries and make a Power bank. on whatever old laptop battery pack you might be tossing out. Most of the time, laptop battery packs go bad when just a few cells in the pack are dead. the protection circuit cuts out the entire pack as a necessary protective measure for the user. There are still a few good cells though. Please check which batteries are good though checking how well the cell can discharge(as most old ones develop high interenal resistance), and how long the cell can keep its charge.
Step 1: Open Battery Pack
find the weak spot somewhere along the seams, and pry until the pack pops open. the packs are usually ultrasonic welded along the seams, with added double sided tape
continue prying.. these cells are held together with some sort of adhesive and snap-on tabs, too.
pull the cell assembly out of the pack.. they are normally held in by double sided tape.Be very careful when removing the cell assembly.. try not to bend the tabs as they could meet and short, resulting in a fire or explosion. (if left shorted)
cut the weakest link, and separate the cells carefully. remove the protection circuit, being very careful not to short out anything.. avoid contacting 2 separate metal pieces if you are unsure about polarity. keep all the tabs separate. While doing this I accidentally touched 2 tabs onto another tab, giving me a big ol' spark and heatup of those cells.
separate the cells from each other
twist the solder tabs off with pliers
Check the voltage. Unfortunately my cells voltage is very low so I used another good batteries.
I ordered a power bank case with board from AliExpress.
Here is the link to buy - http://s.click.aliexpress.com/e/crMApKAc
Now put the batteries one by one make sure you put the batteries in the correct polarity.
Charge the batteries using micro usb
Now put it back to the aluminium case and put the front panel that's it it's ready to go.
Now iam charging.in the case it says 2amp output but actually it is 1amp this power bank worth its money because it cost only 1.80$. the Chinese seller says it's diy power because there is no batteries in it.