It depends on your mod. Most single-battery mods take an 18650, but many newer high-wattage mods are built for 21700 cells. Check your mod’s user manual or the manufacturer spec sheet. Some mods accept both sizes with an adapter. If you are unsure, our 18650 vs 21700 vs 20700 guide explains the differences clearly.

mAh stands for milliamp-hour and indicates how much charge a battery holds. A higher mAh rating means longer use between charges. A 3000mAh cell will last noticeably longer than a 2500mAh cell in the same device, all else being equal. That said, mAh alone does not tell the full story.

CDR stands for continuous discharge rating and tells you the maximum current a battery can deliver safely on a sustained basis. For sub-ohm vaping, this matters a lot. Running a battery beyond its CDR causes it to overheat, which is both a performance and safety issue. If you are vaping at 60W or above, prioritise CDR alongside capacity when choosing a cell. Our sub-ohm vaping guide covers this in more detail.

21700 cells are physically larger than 18650s and typically offer higher capacity and better CDR. They suit high-wattage mods designed to take them. 18650 cells are smaller, more widely compatible and still more than adequate for most vaping setups. The right choice depends on your mod’s battery slot, not just what sounds more powerful.

Most quality lithium-ion cells hold up well for 300 to 500 charge cycles before capacity starts to drop noticeably. How long that takes in real terms depends on how often you vape and how you charge. Using a dedicated charger rather than charging through the device’s USB port helps extend cell life. Once a battery is noticeably running out faster than it used to, it is time to replace it.

Look for nicks, tears, peeling at the edges or any area where the coloured plastic sleeve has pulled away from the cell. Even a small tear near the positive or negative terminal is a problem. A damaged wrap can allow the cell to short-circuit if it contacts metal inside the mod. If you spot any damage, stop using the battery. Most local vape shops can rewrap a cell, or you can replace it entirely.

No. Not all 18650 batteries are suitable for vaping. A cell rated for torch use or low-drain electronics may not be able to safely deliver the current a vape mod demands. Always use batteries from reputable brands with verified CDR ratings. Avoid anything with suspiciously high specs from unknown sources, because rewrapped or counterfeit cells with inflated ratings are a genuine risk.

The simplest check is to cross-reference the battery’s claimed specs against independent test data. Battery tester Mooch is the most widely cited source in the vaping community, and his results are freely available online. If a battery claims a 40A CDR but no credible test confirms anything close to that, treat it with caution. Buying from established brands like Molicel, Vapcell and Fogstar through a reputable retailer removes most of this risk entirely.

Always store loose cells in a dedicated battery case, never loose in a pocket, bag or drawer where they can contact keys, coins or other metal objects. Keep them away from direct heat, moisture and sunlight. A cool, dry place is ideal. Do not stack cells without protection between them.

A dedicated battery charger is the better option for most vapers. Charging through your mod’s USB port works in a pinch, but a quality external charger gives you better control over charge rate, lets you charge multiple cells simultaneously and is generally gentler on the cells over time. If you are buying removable batteries for the first time, a charger should be on your shopping list too.

Yes, most mods with removable batteries do support USB charging. It is convenient but not ideal for long-term cell health. USB charging through the device is slower, less regulated and harder on the battery than a dedicated charger. Use it when you need to, but for regular charging, a proper battery charger is the better habit.

Do not put lithium-ion cells in household waste or recycling bins. Most supermarkets, electronics retailers and council recycling centres have dedicated battery collection points. Many vape shops will also take old cells. Disposing of them correctly keeps hazardous materials out of landfill and is a legal requirement under UK waste regulations.