21700 battery cells for higher energy per weld

A 21700 cell is about 50% larger by volume than an 18650, which buys either more capacity at the same current, or far more current at the same capacity. Twelve models on file.

In one paragraph

A 21700 cell is a 21 mm diameter, 70 mm long cylindrical lithium-ion cell. Current models run from 4,000 mAh at 45 A up to 5,650 mAh at 12.5 A, covering both traction and storage duties.

Why this format

What decides whether it is the right choice

Fewer parallel strings for the same pack capacity, which reduces balancing complexity and interconnect count

The only cylindrical format where 5,000 mAh and 60 A continuous coexist in one part

Preferred in new traction and storage designs; 18650 remains dominant in legacy and compact tooling

Models on file

Current specification table

Sorted by continuous discharge. Every figure is quoted with the condition the manufacturer attaches to it.

Model	Brand	Format	Capacity	Cont. discharge	Max charge	Energy	Source
INR21700-P50B	Molicel	21700	5,000 mAh	60 A	25 A	18.0 Wh	Datasheet
INR21700-P50S	Molicel	21700	5,000 mAh	60 A	25 A	18.0 Wh	Datasheet
INR21700-P45B	Molicel	21700	4,500 mAh	45 A	13.5 A	16.2 Wh	Datasheet
INR21700-P42A	Molicel	21700	4,200 mAh	45 A	—	15.5 Wh	Datasheet
INR21700-40T	Samsung SDI	21700	4,000 mAh	35 A	—	—	Pending
INR21700-50S	Samsung SDI	21700	5,000 mAh	25 A	6 A	18.0 Wh	Pending
INR21700-M50LT	LG Energy Solution	21700	4,800 mAh	14.4 A	—	—	Pending
INR21700-M58T	LG Energy Solution	21700	5,650 mAh	12.5 A	—	—	Pending
INR21700-50GB	Samsung SDI	21700	4,900 mAh	9.8 A	—	—	Pending
INR21700-50E	Samsung SDI	21700	4,900 mAh	9.8 A	—	—	Pending
INR21700-M50T	LG Energy Solution	21700	5,000 mAh	7.275 A	—	18.2 Wh	Pending
INR21700-53G	Samsung SDI	21700	5,300 mAh	—	—	—	Pending

Selection map

Which grade, for which job

Energy-first (5,000–5,650 mAh, 7–15 A)

Residential and commercial storage, long-runtime portable equipment

Balanced (4,200–5,000 mAh, 25–45 A)

E-mobility traction, professional power tools, industrial UPS

Current-first (4,500–5,000 mAh, 45–60 A)

eVTOL, heavy-lift drones, motorsport, data-centre backup units

Common questions

Before you specify

Do the discharge figures assume a temperature cut-off?

Yes, and that is the point. A 60 A figure valid only while the pack holds the cell under an 80 °C surface cut cannot be used in a pack with no thermal path. Where a manufacturer states a condition, we publish it alongside the number.

Can cells of different models share one pack?

No. Cells of different model, batch or state of charge must not be mixed in one pack. Uneven cells force the BMS to cut early at both ends and the pack loses the capacity it was specified for.

What documentation ships with an order?

UN38.3 test summary, MSDS and the transport classification for the shipping configuration. Certificate numbers are quoted only for documents we actually hold, and only where the model appears in the certificate coverage list.

Other formats

If this one does not fit

18650 cells Energy storage cells 4680 (not stocked) Prismatic cells Cell comparisons Cell selection guide

Narrowing down? Send the load profile

Peak current, continuous current, duty cycle and target cycle life. We will come back with the candidates and the documentation behind each one.

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