Update 9/29/2019:
Buying 18650 cells on ebay is tricky. Many weigh only 22 grams and are no where near what they claim the rated ampere * hours is. I replaced the cells in a cordless screwdriver and found that the torque was not as good as original cells. This is likely due to current supplied being low as torque in an electric motor is proportional to currect flow through the motor.
Research Links
- Summary of Testing Results: Test of cheap Li-Ion 18650 cells – beware of fakes – Diodes Gone Wild Youtube Channel
- YouTube: Cheap Ebay Li-Ion 18650 cells (some REAL)
- YouTube: Cheap Fake Ebay 18650 Li-Ion batteries – TEST & AUTOPSY
- YouTube: Testing more 18650 Li-ion cells (REAL vs. FAKE)
Dimensions in inches: 2.56 x 0.315 inches. Wikipedia: List of Battery Sizes
The 18650 lithium cell battery can be purchased for on the order of 1 dollar per cell on ebay. This makes it very attractive for fixes to devices whose battery packs have died. Also of interest is the fact that since the lithium cell voltage is 3.7 volts less cells are required to replace a NiCad pack. This means that in many cases there will be sufficient space for the lithium cells to fit in the old battery pack.
Research Links
- YouTube: DIY Battery Spot Welder – Demonstration & Explanation – to connect cells using nickel strapping
- YouTube: How to make Crappy Ni-Cad cordless tools useful again by converting them to Li-ion Power – Example fix. Includes battery balancing in the charging circuit
- YouTube: DIY battery pack 5 cell (5S, 18.5V) – Uses individual cell spacers to rack up the cells. Uses battery balancing
- Ebay: 18650 cell spacer
- Ebay: 20pcs BXE 18650 Battery 9800mAh Li-ion 3.7V Rechargeable Lithium Batteries Cell – 1.07 per cell makes this a very economical recell potential. EbayUser: liuqq0609
- Youtube: Must LITHIUM BATTERIES be BALANCE CHARGED ? #15 – battery balancing charger needed? It depends.
- Youtube: Upgrade Black & Decker 18v Single Source to Lithium Ion for $5 – replaces NiCad with Li ion.
- Battery Cell Balancing:- What to Balance and How Yevgen Barsukov, Texas Instruments – PDF
- A Designer's Guide to Lithium (Li-ion) Battery Charging
- FreeScale: Active Cell Balancing in Battery Packs
- Ebay: lithium battery 5 cell balance charger
Battery Protection and Balance Circuit
How To Convert / Replace Ni-Cd To Lithium by using 18650 cells li-ion
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