18500 and 22700 cells: the less common cylindrical formats
Two formats that sit either side of the mainstream. The 18500 is a shortened 18650; the 22700 is a wider can that holds more capacity without moving to 21700 tooling.
In one paragraph
An 18500 cell is 18 mm in diameter and about 49 mm tall — shorter than an 18650, for products with a shallow battery bay. A 22700 cell is about 22 mm by 70 mm, which holds 5,600 mAh class capacity in a can that is wider but no taller than an 18650.
Why this format
What decides whether it is the right choice
18500 keeps the 18 mm tooling and diameter while removing roughly 15 mm of height
22700 delivers 5,000 mAh class capacity in a can shorter than a 21700, which suits legacy pack designs
Both are niche formats — expect narrower second-source options than 18650 or 21700
Models on file
Current specification table
Sorted by continuous discharge. Every figure is quoted with the condition the manufacturer attaches to it.
How the four cylindrical formats compare
| Format | Diameter | Height | Typical capacity | Where it comes from |
|---|---|---|---|---|
| 18500 | 18 mm | About 49 mm | 1,500 – 2,100 mAh | A shortened 18650, for shallow bays |
| 18650 | 18 mm | 65 mm | 2,000 – 3,500 mAh | The default format for most pack designs |
| 21700 | 21 mm | 70 mm | 4,000 – 5,650 mAh | Larger can, fewer cells per pack |
| 22700 | 22 mm | About 70 mm | About 5,600 mAh | A wider can that keeps 18650-class height |
Capacities are the ranges present in this catalogue; individual models vary.
Why these two formats still exist
Formats survive because tooling survives. A product designed around an 18500 bay cannot take an 18650 without a mechanical change, even though the electrical difference is modest. The same is true of the 22700: a pack built for a 22 mm holder will not accept a 21 mm cell without new hardware, and the capacity difference is not always worth the redesign.
The consequence for sourcing is the one worth planning around. Neither format has the manufacturer depth of 18650 or 21700, so second-source options are thin and lead times are less predictable. If the product can accept a mechanical change, moving to a mainstream format improves supply resilience more than it improves the data sheet.
When a niche format is the right call
- The enclosure is fixed and cannot grow by 15 mm of height (18500) or shrink by 1 mm of diameter (22700).
- The product is a retrofit or a service part for an existing platform, where the format is part of the interface.
- Volumes are low enough that re-tooling costs more than the supply risk of a single-source part.
In every other case, start from 18650 or 21700 and treat these two as the exception that mechanical constraints justify — not as a capacity decision.
Selection map
Which grade, for which job
18500 (about 2,000 mAh)
Shallow bays in medical and instrumentation products, where 65 mm will not fit
22700 (about 5,600 mAh)
LEV, robotics and storage packs already tooled for a 22 mm can
Mainstream alternatives
If the envelope allows, 18650 and 21700 have wider grade spreads and better availability
Common questions
Before you specify
Do the discharge figures assume a temperature cut-off?
Can cells of different models share one pack?
What documentation ships with an order?
Other formats
If this one does not fit
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.