Side-by-side comparison of Samsung INR21700-40T (21700) and Sanyo UR18650NSX (18650)
| Samsung INR21700-40T | Sanyo UR18650NSX | |
|---|---|---|
| Capacity | 4000 mAh | 2600 mAh |
| Nom. Voltage | 3.6 V | 3.6 V |
| Max Current | 35 A | 30 A |
| Weight | 70 g | 44 g |
| Energy | 14.4 Wh | 9.4 Wh |
| Energy Density | 206 Wh/kg | 213 Wh/kg |
| Form Factor | 21700 | 18650 |
| Typical R_int | 19.8 mOhm | 17.0 mOhm |
Showing 10A discharge rate for both cells
| Current | Samsung INR21700-40T | Sanyo UR18650NSX |
|---|---|---|
| 0.2A | — | 17.0 |
| 0.5A | — | 17.0 |
| 0.8A | 19.8 | — |
| 1.0A | — | 24.5 |
| 2.0A | — | 27.2 |
| 3.0A | — | 26.8 |
| 4.0A | 17.1 | — |
| 5.0A | — | 25.3 |
| 7.0A | — | 23.9 |
| 10.0A | 17.1 | 22.4 |
| 15.0A | — | 20.6 |
| 20.0A | 16.6 | 19.5 |
| 30.0A | — | 18.2 |
| 35.0A | 16.2 | — |
Values in mΩ. Bold = lowest resistance at that current.
The Samsung 40T offers 54% more capacity (4000 vs 2600 mAh). The Samsung 40T supports higher continuous discharge (35A vs 30A), making it better for high-drain applications. The Sanyo UR18650NSX has better energy density (213 vs 206 Wh/kg). The Sanyo UR18650NSX is lighter at 44g. Note: these are different form factors (21700 vs 18650), so direct substitution is not possible without pack redesign.