18650
18mm x 65mm
18650 Battery Types
| Type | Main Composition | Features | Applications |
|---|---|---|---|
| NCM/NCA | Nickel-Cobalt-Manganese / Nickel-Cobalt-Aluminum | High energy density, medium safety | EVs (Tesla Model S/X), laptop batteries |
| LFP (Lithium Iron Phosphate) | Lithium Iron Phosphate | Long lifespan, high safety, lower energy density | Energy storage, power tools, e-bikes |
| LCO (Lithium Cobalt Oxide) | Lithium Cobalt Oxide | High energy density, shorter lifespan | Laptops, battery packs |
| IMR (Lithium Manganese Oxide) | Lithium Manganese Oxide | High discharge rate, heat resistance | High-power flashlights, vaping devices |
18650 vs. 21700 Batteries
| Model | Size | Energy Density | Common Uses |
|---|---|---|---|
| 18650 | 18 × 65 mm | 2000 – 3500mAh | Laptops, EVs, tools |
| 21700 | 21 × 70 mm | 4000 – 5000mAh | Tesla batteries, energy storage |
Tesla originally used 18650 batteries in Model S/X but later switched to 21700 for Model 3/Y and is now moving towards 4680 cells for higher efficiency.
The 18650 battery should fall under the Lithium-ion Battery category, as it is a specific form factor of the lithium-ion battery, commonly used in applications such as laptops, power tools, flashlights, and electric vehicles.
safety concern
After 30 years of development, the preparation process of 18650 battery has been very mature. In addition to the great improvement in performance, its safety is also perfect.
To prevent the metal casing from exploding, the battery is now fitted with a safety valve at the top. The safety valve is now a standard part of every 18650 Li-ion battery and is the most important barrier. When the pressure inside the cell becomes too high, the top safety valve opens to vent and depressurize, preventing an explosion.
However, when the safety valve is open, chemicals leaking from inside the battery can react with oxygen in the air at high temperatures and still cause a fire.
In addition, most 18650 batteries now also come with their own protection panel with overcharge and overdischarge and short circuit protection, which has high safety performance.
CID safety
The CID (Current Interrupt Device) in an 18650 battery is a safety feature designed to prevent overheating and potential hazards. If the internal pressure of the battery gets too high (usually due to overcharging or overheating), the CID disconnects the circuit, stopping the current flow to prevent a dangerous situation, such as thermal runaway or explosion.
Each manufacturer might have slightly different specifications, but the CID is a common safety component in lithium-ion batteries, especially in high-capacity cells like the 18650.
CID reset trick
short test
- https://www.youtube.com/watch?v=bKQzfrO6WBA&ab_channel=EngineerX
- https://www.youtube.com/watch?v=AUMiSk1D4Xg&ab_channel=DIYTech%26Repairs