Panasonic is very clear on this: The NCR21700T is designed for spot-welded nickel strips. Soldering irons transfer too much heat into the cell, melting the internal separator and causing an internal short. If you see a loose NCR21700T with solder blobs on it, run away.
Mechanically, no – the 21700 is larger (21mm vs 18mm diameter). Electronically yes, if your device has a larger battery holder and supports the higher capacity. panasonic ncr21700t datasheet
Keep in mind that these specifications might not be comprehensive or up-to-date. If you need accurate and detailed information, I recommend finding the official datasheet from Panasonic or a reliable source. Panasonic is very clear on this: The NCR21700T
The Panasonic NCR21700T is a high-performance lithium-ion battery cell that has gained significant attention in the industry due to its impressive specifications and capabilities. As a leading manufacturer of rechargeable batteries, Panasonic has established a reputation for producing high-quality cells that cater to a wide range of applications, from consumer electronics to industrial and automotive uses. Mechanically, no – the 21700 is larger (21mm
Based on testing and related documentation for the Panasonic 21700 family, here is the breakdown of its performance: Specification (Approx.) Nominal Capacity 4,800 mAh to 5,000 mAh Nominal Voltage Max Charge Voltage Standard Charge Current 2.5A (approx. 0.5C) Continuous Discharge 10A (Optimal) up to 15A Max Discharge (Pulse) Up to 20A (with significant heat/sag) Energy Density ~263 Wh/kg Why This Cell Matters