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Notes on 18650 cells

If you're familiar with reclaiming 18650 cells from laptop battery packs (and the like), you'll probably know that the level of the positive terminals are often flush with the outer negative terminal, albeit insulated from it. This probably makes them safer in some ways as the terminals won't short easily, but it makes them harder to use in a linear, series-connected configuration as the positive terminals simply aren't sticking out enough to contact the cell mounted in front of it. Any DIY or modified-for-type terminals for connecting to the cell positive are, therefore, going to need to stick out from their mounting in order to make contact with the flush positive terminal on the (reclaimed) 18650 cell.

above: View showing nickel strip used as positive terminal

The image above shows a reclaimed 18650 cell with a small section of the nickel strip folded over itself to imitate a protruding positive terminal. This will enable the cell to be used in series with others, as the folded nickel strip will allow the cell to make contact with the one in front. When preparing the terminal in this way, it's important to be aware of the sharp edges from the nickel strip/s. It's also important to make sure the strip isn't about to fatigue and break off after it's been bent, because it's possible this could get stuck between the positive terminal and the outer negative case, causing a direct short. These cells are capable of delivering a very high current, and should be treated with respect. It's probably a good idea to avoid preparing them when they're fully charged!



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