If your laptop/notebook or netbook has been changed the battery unit with the new one. don't waste the old battery unit although it doesn't work anymore. Because generally inside the battery unit, not all the battery cell are bad. even in more case, in the battery unit that has 6 battery cells only one or two battery cells have malfunction. One cell has a problem, it will cause the battery unit becomes malfunction. Use the cutting pliers to rip the battery cover, or you have the other way, up to you. Take out all the batteries, generally has model 18650 battery, be care full don't make short circuit. You have to know the polarity which Positive and negative Use the 18650 battery charger to know it still can be charged or not, you can see the LED indicator, if not charging means the battery is bad. (You can buy 18650 battery charger from online market, from Aliexpress the price below 2 dollars) Can be used for Power Bank There are m...