14500 is the same well-known AA size we used to see. It means that the diameter of the cell is 14mm and it's 50mm long. 14500 is used to refer to 3.7V Li-ion or 3.2V LiFePO4 cells while AA is for 1.5V alkaline/other primary batteries and 1.2V Ni-Cd or Ni-MH rechargeable cells. Let's look at the difference in size between AA/14500 and other popular formats: From the top to the bottom and the left to the right there are AAA/10440, AA/14500, 18650, 26650 and the new 26800 size. Queen Battery QB14500 is a flat-top unprotected 700mAh-rated cell which also can be ordered with add-on protection PCB and button-top cap. The battery was bought from Queen Battery which is my reliable supplier of genuine cells and tested with ZKETECH EBC-A20 and a self-made battery holder. It's a PC-connected battery tester supporting 4-wire measuring and discharging at up to 20A. I've used version 3.0 of my battery holder based on 0.5mm thick pure copper terminals I
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