21700 Lithium-Ion Battery Cells

A 21700 cell is a cylindrical rechargeable battery with an approximate diameter of 21 mm and length of 70 mm. The actual dimensions vary slightly by manufacturer and design. Versions with welded tabs, insulation accessories, or a protection circuit may need additional installation space. Check the exact mechanical drawing and datasheet before finalizing an enclosure or battery pack.

Compared with the approximately 18 × 65 mm 18650 format, a 21700 cell has a larger 21 × 70 mm form factor. Many 21700 models offer greater capacity per cell, which can reduce the number of cells needed for a given pack energy target. However, total pack size, weight, current delivery, cooling, and cost depend on the selected model and pack design. The two sizes are not mechanically interchangeable.

Many high-energy 21700 lithium-ion models have rated capacities around 4,000–6,000 mAh, while high-power models may prioritize discharge capability over capacity. Common NMC/NCA-type cells typically have nominal voltages around 3.6–3.7 V. Other chemistries can use different nominal and charging voltages. Confirm the rated capacity, maximum charge voltage, discharge cutoff, and test conditions in the specific manufacturer's datasheet.

High-capacity 21700 cells are generally optimized for longer runtime and higher energy, while high-discharge cells are designed to support higher loads. A 5,000 mAh rating alone does not tell you whether a cell is suitable for a power tool or an e-bike controller. Compare continuous and pulse discharge limits, temperature conditions, cycle life, and any required cooling. The right choice depends on your actual load profile.

Start with the pack's nominal voltage, energy target, continuous and peak current, working temperature, space, and cycle-life requirements. Determine the series and parallel configuration, then check the estimated current per cell and the manufacturer's thermal and discharge limits. Also review the BMS, busbars, wiring, charging profile, and mechanical protection. Misen Power can compare candidate 21700 models against these project requirements.

Not as a direct drop-in replacement. A 21700 cell is wider and longer, so the holders, enclosure, cell spacing, busbars, and thermal design may need to change. Electrical compatibility must also be checked, including chemistry, voltage limits, discharge performance, charger settings, and BMS configuration. Any redesign should be validated by the battery pack engineer before production or installation.

Yes. Provide your preferred manufacturer and part number, or share your required capacity, discharge current, dimensions, application, and order quantity. We can review sourcing options and suggest technically comparable 21700 cell candidates where available. A proposed substitute should still be approved through datasheet comparison, mechanical checks, and application-level testing. Brand, batch availability, and commercial terms are confirmed case by case.

Depending on the project, Misen Power can discuss 21700 cell matching, welded-tab configurations, and custom battery pack assembly. Please provide the series/parallel arrangement, pack voltage and capacity, continuous and peak current, BMS requirements, connector type, enclosure dimensions, and expected quantity. Available processes, acceptance criteria, testing arrangements, and production lead time will be confirmed during technical review.

Minimum order quantity depends on the brand, specific 21700 model, stock status, and any custom requirements. Sample quantities may be available for technical evaluation, subject to inventory and shipping arrangements. To request a quotation, send the exact model or target specification, quantity, delivery country, and estimated recurring demand. We will confirm practical sample, bulk purchase, and lead-time options.

For selected 21700 models, available documentation may include manufacturer datasheets, SDS/MSDS, and UN38.3 test summaries. Voltage, internal resistance, appearance, or other inspection checks can be discussed according to the order requirements. Lithium-ion cells are regulated for transport, and permitted shipping methods, packaging, labels, and documents depend on the cells, quantity, destination, and carrier. We confirm the available documents and shipping options for each order.