Side-by-side comparison of Samsung INR18650-30Q (18650) and Samsung INR21700-40T (21700)
| Samsung INR18650-30Q | Samsung INR21700-40T | |
|---|---|---|
| Capacity | 3000 mAh | 4000 mAh |
| Nom. Voltage | 3.6 V | 3.6 V |
| Max Current | 15 A | 35 A |
| Weight | 45.6 g | 70 g |
| Energy | 10.8 Wh | 14.4 Wh |
| Energy Density | 237 Wh/kg | 206 Wh/kg |
| Form Factor | 18650 | 21700 |
| Typical R_int | 21.9 mOhm | 19.8 mOhm |
Showing 10A discharge rate for both cells
| Current | Samsung INR18650-30Q | Samsung INR21700-40T |
|---|---|---|
| 0.6A | 21.9 | — |
| 0.8A | — | 19.8 |
| 3.0A | 19.9 | — |
| 4.0A | — | 17.1 |
| 5.0A | 18.9 | — |
| 10.0A | 18.9 | 17.1 |
| 15.0A | 18.3 | — |
| 20.0A | 18.3 | 16.6 |
| 35.0A | — | 16.2 |
Values in mΩ. Bold = lowest resistance at that current.
The Samsung 40T offers 33% more capacity (4000 vs 3000 mAh). The Samsung 40T supports higher continuous discharge (35A vs 15A), making it better for high-drain applications. The Samsung 30Q has better energy density (237 vs 206 Wh/kg). The Samsung 30Q is lighter at 45.6g. Note: these are different form factors (18650 vs 21700), so direct substitution is not possible without pack redesign.