21700 Li-ion cell
Li-ion NMC 21700 · 3.7 V nominal · 5000 mAh · 90% charged
Try it on the benchThe lab drops it on an empty bench and opens its datasheet card.
Typical part: 21700 Li-ion (NMC), e.g. Samsung 50E / Molicel P45B class
Ratings and limits
| Voltage | 2.5–4.2 V, 3.6–3.7 V nominal |
|---|---|
| Capacity | 5000 mAh typical (4500 mAh on high-drain types) |
| Internal resistance | ≈ 15–25 mΩ |
| Discharge | 10 A continuous typical, 30–45 A on high-drain types |
| Charge | CC/CV to 4.2 V at ≤ 0.5–1 C |
How to use it
The 18650’s successor: 21 mm × 70 mm, about twice the energy of a 2500 mAh 18650 with lower resistance. Used in e-bikes, power tools, Tesla Model 3 packs and big power banks. Always protect it with a BMS.
Lessons and builds that use it
- 10,000 mAh power bank · 2 × 21700 (build)
- 20,000 mAh power bank · 4 × 21700 (build)
- 40,000 mAh power bank · 8 × 21700 (build)