18650 vs 21700 Battery Packs – Extended Technical Comparison
| Metric | 18650 Pack | 21700 Pack | Notes |
|---|---|---|---|
| Cell size | Ø18×65 mm | Ø21×70 mm | 21700 is ~35% larger in volume, enabling higher capacity per cell. |
| Typical single-cell capacity | 2.5–3.5 Ah | 4.0–5.8 Ah | Samsung 50E / 50GB are common high-capacity 21700 examples. |
| Weight per cell | ~45 g | ~65–70 g | 21700 is heavier but offers more Wh per gram overall. |
| Gravimetric energy density | ~150–220 Wh/kg | ~180–260 Wh/kg | Depends on cathode chemistry (NMC/NCA). |
| Continuous discharge (per cell) | 10–20 A (high-power up to 30 A) | 15–40 A (high-power up to 45 A) | 21700 provides more headroom for e-bikes and power tools. |
| Cycle life | 500–1,000 cycles | 600–1,200 cycles | At the same DoD, 21700 typically lasts longer. |
| Pack design | More parallels; more weld points | Fewer parallels; fewer welds | Fewer cells simplify assembly and reduce failure points. |
| Thermal management | Smaller surface area; denser layout | Larger surface; better heat spreading | 21700 runs more stable at higher loads with proper design. |
| Applications | Laptops, medical, compact packs | E-bikes, scooters, power tools, ESS | 21700 is becoming mainstream for mobility and storage. |
| Market maturity | Very mature; broad supply | Rapidly growing; stabilizing supply | 18650 is established but often replaced by 21700 in new designs. |
| Cost per Wh | Lower | Slightly higher | 21700 cost/Wh continues to drop as adoption increases. |
Choosing the right 18650 battery pack supplier is not just about price—it’s about engineering trust, consistent quality, and long-term support. Here’s why B2B buyers in mobility, medical, and industrial sectors partner with us.
