EVs, e-bikes and power tools have moved from 18650 to 21700 cells. Here's what changed, which cells lead the market, and what it means for pack builders.

For more than two decades the 18650 was the default rechargeable lithium-ion cell, found in laptop packs, flashlights, power tools and early electric cars. Over the last several years much of the industry has moved up a size to the 21700. Here's what changed, why it happened, and what it means if you build or buy battery packs.

Shop: Molicel P50B 21700 5000mAh 60A Battery

Just 3mm wider and 5mm longer, but a lot more energy

An 18650 measures 18mm × 65mm and a 21700 measures 21mm × 70mm. That small change adds roughly 45–50% more internal volume. Since the can, cap and safety parts take up about the same space in both, more of that extra volume goes to active material. The practical result:

	Typical high-end 18650	Typical high-end 21700
Capacity	~3,000–3,500mAh	~4,000–6,000mAh
Energy per cell	~11–12.5Wh	~14–21Wh
Weight	~45–50g	~65–75g
Cells for a 1kWh pack	~80–90	~50–70

Fewer cells per pack means fewer welds, fewer connections that can fail, simpler balancing and lower assembly cost.

What drove the shift

Electric vehicles led the way

The move went mainstream when Tesla and Panasonic introduced the "2170" (21700) cell for the Tesla Model 3, built at the Nevada Gigafactory, replacing the 18650s used in earlier models. Once the highest-volume EV maker standardized on the size, cell makers poured investment into 21700 production lines. Tesla has since introduced the larger 4680 format, but 21700 remains a workhorse across EVs and energy storage.

E-bikes, scooters and light EVs

E-bike packs need high capacity in a frame-mounted case. A 52V 21700 pack can hold the same energy as an 18650 pack with fewer cells, or more range in the same space. Many e-bike and scooter makers now offer 21700 packs, especially at the premium end.

Power tools

Cordless tool makers moved their high-output battery lines to 21700 cells to deliver more current under load and run cooler. Tools like grinders, chainsaws and table saws draw large currents that benefit from lower-resistance cells.

Cells that do both: capacity and power

The biggest recent change is cells that don't force a trade-off. A few years ago you chose high capacity or high current. Today's 21700s offer both:

• Samsung 40T: 4,000mAh with 35A max continuous (Samsung spec)
• Samsung 50S: 5,000mAh with 25A max continuous (Samsung spec)
• Molicel P42A: 4,200mAh high-drain
• Molicel P50B: 5,000mAh high-drain
• Molicel P60B: 6,000mAh, among the highest-capacity 21700s available

Shop: Molicel INR-21700-P60B 6000mAh 3.6V 100A High-Power 21700

Is the 18650 going away?

No. The 18650 is still produced in huge volumes and remains the right choice when:

• Your enclosure, battery holder or existing pack design is sized for 18650s
• You need the lowest cost per cell for lower-power products
• Your devices already take a loose 18650 (flashlights, test gear, many chargers)
• You need proven, widely available cells like the Samsung 30Q, LG MJ1 or Molicel P28A

Some products also use 20700 cells, like the Hohm Tech Sherlock2 20700. These are a middle ground for devices that need a little more energy than an 18650 without the full 21700 length.

Shop: Samsung 40T 21700 – 4000mAh Battery (Bulk)

What this means for pack builders and manufacturers

• Redesigning a product? Look at 21700 first. You'll likely cut cell count by a third and gain runtime.
• Re-certifying? Changing cell format usually means updated UN38.3 testing for the finished pack. Start with cells that have their own UN38.3 and IEC 62133 documentation. Find what we have on file in our 18650 Data Center.
• Supply continuity: lock in a supplier who can deliver the same cell model consistently. Switching cell models mid-production can mean new testing.

Browse our 21700 batteries, or request bulk pricing for production volumes.

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18650 21700 Industry News

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