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Old 12-26-17, 06:54 AM   #3
jeff5may
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The danger of running lithium battery cells happens when trying to discharge them completely. Unlike the nickel chemistry type, the lithium cells can never be discharged to near zero volts. If the cells are discharged, they polymerize and liberate heat in the process. In the case of tablets or phones (or an ever-increasing number of compact high-drain devices), the battery can melt or burn its enclosure.

Running laptop cells (18650) to power hand tools is a common industry practice. Naturally the top tier manufacturing companies are going to use a different cell in the Shell just so they are difficult to swap out. The big dogs couldn't charge 75 dollars or more for a battery if they had common cells inside: the aftermarket would undermine the price.

The single most important thing to include in the battery pack is a BMS, or battery manager system. These are a combination of a smart charger and a smart discharger. All of the laptop battery packs have one in them in order to meet safety and liability standards in Europe and America. They can be found as cheap and barebone or expensive and snazzy as you desire on the normal auction websites. More discharge current and higher voltage BMS cost more than low voltage and low drain. Just figure out your peak current draw and max voltage and order accordingly.
Cheaper than dirt $3

Still cheap $7

Not cheap $22
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