Efest

A replacement cell has to fit your device's battery bay and meet the current your device draws, and your charger has to accept the cells you own. Our Efest range has lithium-ion cells in 18350, 18650, 21700 and 26650 sizes plus four chargers, priced from $9.99 to $36.99.

Four cell sizes: matching 18350, 18650, 21700 or 26650 to your battery bay

The four-digit number in an Efest battery name is the cell's size code, and each code stands for a different physical cell. Your device's manual or battery door shows the size it takes, and that size decides which cell fits. Don't substitute a cell with a different code, even when the codes look alike, as 18350 and 18650 do.

Our Efest cells by size:

• Efest INR 18350: 1200 mAh, 3.7V
• Efest INR 18650: 3000 mAh, 3.7V
• Efest INR 18650: 3500 mAh, 3.7V
• Efest IMR 21700: 3700 mAh, 35A, sold as a two-pack
• Efest IMR 26650: 4200 mAh, 50A, 3.7V

Every listing here that states a voltage gives 3.7V, so voltage won't help you choose between these cells. Size, capacity and current rating will. The larger cells in this range have higher listed capacities, but a larger cell only helps if your device has a bay built for it.

Capacity in mAh versus current rating in amps

An Efest cell name can carry two separate performance figures. Capacity, in mAh (milliamp-hours), is how much charge the cell stores. The amp (A) figure is how much current the cell is rated to deliver. They're different specifications. Your device's manual tells you how much current the device needs, and that's the figure to compare with a cell's amp rating.

In our catalogue, only two cells have a current rating in the product name: the 21700 (35A) and the 26650 (50A). The 18350 and both 18650 listings show only capacity and voltage, so confirm the current rating of those cells before you buy. The 18650 comparison below shows why it matters.

Choosing between the 3000 mAh and 3500 mAh 18650

Efest's own battery list shows a tradeoff within one cell size. In that list, Efest rates its IMR 18650 3500 mAh cell at 20A and its IMR 18650 3000 mAh cell at 35A, so the higher-capacity cell has the lower current rating. Those are Efest's ratings for its IMR cells. Our 18650 listings are labelled INR, so confirm the rating of the exact cell you're buying. Match the current rating to what your device draws first, then choose capacity. More mAh doesn't make a cell the better pick if your device draws more current than that cell is rated for.

Choosing an Efest charger

We carry four Efest chargers: the Slim K1 Single Charger, the Lush Q2, the Lush Q4 and the PRO C2. The Slim K1's name tells you it's single-bay, so it suits charging one cell at a time. For the Lush Q2, Lush Q4 and PRO C2, check the product page for the number of bays and the cell sizes each charger accepts before you buy.

Your choice comes down to how many cells you charge at once and which sizes they are. For example, if you buy the 21700 two-pack and want to charge both cells together, you need a charger that takes 21700 cells and has at least two bays. Whichever charger you choose, follow the manufacturer's instructions for the charger and the cells. The rest of our vape hardware range is listed separately.

Storing, carrying and charging spare cells

Health Canada publishes tips for preventing injuries from lithium-ion batteries used with vaping devices. Its vaping product safety guidance includes these points:

• Keep spare lithium-ion batteries in a protective case.
• Don't carry spare cells in your pocket or anywhere they can touch loose coins, keys or other metal objects. Health Canada notes that lithium-ion batteries can overheat, catch fire or even explode when in contact with metal objects, and that serious injuries have been reported.
• Read the manufacturer's instructions for storing and recharging, and do not exceed the recommended charging time.
• Don't modify your vaping device.
• Buy lithium-ion batteries that are recommended by the manufacturer and from a trusted source.

The warning about metal applies to a bag holding keys or coins just as much as to a pocket. Keep every spare in a case, including the second cell from a two-pack.