18650 vs 21700
Battery Comparison
Home > Battery Comparisons > 18650 vs 21700
| Feature | 18650 | 21700 |
|---|---|---|
| Diameter | 18mm | 21mm |
| Length | 65mm | 70mm |
| Typical capacity | 2,000-3,500 mAh | 3,000-5,000 mAh |
| Weight | ~45-48g | ~65-70g |
| Energy density | Slightly lower per gram | Slightly higher per gram (improved cell design) |
| Max discharge rate (C-rating) | Varies widely; high-drain versions available | Generally higher continuous current, popular for high-drain uses |
| Common chemistries | Li-ion (NMC, NCA), LiFePO4 | Li-ion (NMC, NCA), LiFePO4 |
| Device compatibility | Very common - laptops, power tools, flashlights, vapes, e-bikes, older EV packs | Growing common - newer EVs (e.g. Tesla Model 3/Y), power tools, high-end flashlights, e-bikes |
| Cost per cell | Lower | Moderately higher |
| Cost per mAh | Often comparable or slightly higher | Often lower (better capacity per cost) |
| Availability | Extremely widespread, many brands | Increasingly common, growing brand support |
| Charger/device compatibility | Fits most standard single/multi-cell holders | Requires holders/devices specifically sized for 21700 cells |
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