Buying Vape Batteries: How to Choose the Right Battery

If you're buying vape batteries for the first time, the rows of numbers printed on the wrappers can make a simple purchase look surprisingly complicated. Do you need an 18650 or a 21700? Is a higher mAh number always better? What does the amp rating actually mean?

The good news is that choosing a battery for a modern regulated vape mod doesn't require an advanced knowledge of electronics. Your vape manufacturer has already done most of the hard work for you. Your main job is to buy the correct size and type of battery, make sure its specifications are suitable for your device and get it from a trustworthy seller.

If you're looking for a replacement cell now, you can browse our vape batteries. If you'd rather understand what all of the specifications mean first, this guide will take you through the important points.

What Should You Check When Buying Vape Batteries?

There are four main things to look at when choosing a removable vape battery:

• Battery size: usually 18650 or 21700 in modern vape mods, although some devices use other formats.
• Discharge capability: the battery needs to be capable of supplying the current demanded by your device.
• Capacity: measured in milliamp-hours (mAh), this gives you a useful indication of how much energy the battery can store.
• Authenticity and condition: the battery should be genuine, undamaged and purchased from a reputable source.

The first of those points is non-negotiable. If your vape requires an 18650, buy an 18650. If it requires a 21700, use a suitable 21700 unless the manufacturer specifically says that the device can also use another battery size with an adapter.

18650 vs 21700 Vape Batteries

Most people buying vape batteries will encounter two numbers again and again: 18650 and 21700. These identify two different cylindrical lithium-ion cell formats.

A 21700 battery isn't automatically “better” simply because it's larger. A compact vape designed around an 18650 may be exactly what you want, and there's no benefit in buying a different cell that doesn't fit the device.

Some vape mods can accept more than one battery format by using a removable sleeve or adapter. If yours does, check the manual carefully before switching between battery types rather than assuming that a smaller cell will fit safely on its own.

What Does mAh Mean on a Vape Battery?

The capacity of a vape battery is usually stated in milliamp-hours (mAh). In simple terms, a battery with more capacity can generally store more energy.

That's why a higher-capacity battery can potentially provide longer vaping time between charges.

There is an important catch, though: capacity isn't the only specification that matters. A battery also needs to supply enough current for the way it's being used. Choosing a vape battery purely because it has the largest mAh number on the shelf isn't a good idea.

Think of capacity as the size of the fuel tank rather than a complete measure of the battery's performance.

What Does the Amp Rating Mean?

A vape battery also has limits on how much electrical current it can safely deliver. This is especially important in higher-powered devices because vaping can place a significant load on a battery.

You may see this specification described as the battery's continuous discharge rating or CDR.

You don't need to buy the highest-rated battery you can find just for the sake of it. You need a battery that's suitable for the requirements of your particular device and the power range in which you intend to use it.

If you're replacing an existing battery, the simplest approach is to check the vape manufacturer's specifications and use the same approved battery type or an appropriate equivalent from a reputable manufacturer.

Does Coil Resistance Determine Which Battery You Need?

Not on its own.

You may have seen older vaping guides say that a lower-resistance coil automatically means that you need a battery with a higher amp rating. That idea comes largely from mechanical vaping, where the coil is connected much more directly to the battery.

Modern regulated vape mods work differently. Their electronics regulate the power supplied to the coil, so the wattage you're asking the device to produce is an important part of the battery load.

For an everyday buyer, there's no need to calculate this yourself if you're using a normal regulated kit. Follow the manufacturer's battery requirements and stay within the device's intended operating limits.

Should Vape Batteries Be “High Drain”?

Removable batteries used in vape mods need to be suitable for the relatively high current demands of vaping. That's one reason why you shouldn't simply buy any cell with the correct dimensions.

For example, 18650 batteries are used in all sorts of equipment. Two batteries can both be labelled “18650” while having very different performance characteristics.

The number describes the battery's physical format; it doesn't guarantee that the cell is suitable for vaping.

When you're buying vape batteries, use cells intended for an appropriate high-drain application and make sure their specifications meet the requirements of your device.

Why Does It Matter Where You Buy Vape Batteries?

Battery authenticity matters more than it does with many ordinary vape accessories.

The plastic wrapper around a lithium-ion cell carries the brand and specifications, but a wrapper isn't proof by itself that what's underneath is genuine. Counterfeit and misleadingly rewrapped batteries have appeared on the market, so buying an unknown cell from an unknown marketplace seller isn't worth the saving.

A reputable vape or battery retailer should have a controlled supply chain and know where its cells have come from.

The UK's Office for Product Safety and Standards also advises vapers to use genuine, recommended batteries for their devices.

In other words, this isn't a particularly good product category for bargain hunting on a marketplace at 1:00 in the morning.

Buying Batteries for a Dual-Battery Vape Mod

If your vape uses two removable batteries at the same time, buy the batteries together as a matching pair.

Use two cells of the same model and specification, and keep them together throughout their working lives. Charge and use them as a pair rather than constantly swapping one battery between different sets.

This practice is often referred to as marrying batteries.

It helps to ensure that both batteries have experienced roughly the same number of charge cycles and similar levels of wear.

If one battery in a long-used pair develops a fault and needs to be retired, it's generally sensible to retire the pair from multi-battery use rather than introducing a brand-new cell alongside a heavily used one.

What Should You Check When a New Vape Battery Arrives?

Don't put a new battery straight into your vape without giving it a quick inspection first.

• Check the wrapper. It should be intact without significant tears or missing sections.
• Check the insulating ring. The insulator around the positive terminal should be present and undamaged.
• Look for dents. Don't use a cell that's crushed, dented or physically deformed.
• Check for corrosion or leakage. Either is a reason to stop using the battery.
• Confirm the specification. Make sure you've received the battery size and model you intended to buy.

Continue checking your batteries periodically after you begin using them. Battery wraps can become damaged when cells are repeatedly removed from and inserted into a device.

Can You Use a Vape Battery with a Torn Wrap?

You shouldn't use a battery with a badly damaged wrap.

The metal body of a cylindrical lithium-ion cell forms part of the battery's electrical structure. The plastic wrap and the insulating ring around the positive terminal help prevent accidental electrical contact where it shouldn't occur.

Minor wrap damage can often be corrected by fitting a proper replacement battery wrap and insulator, but if you're unsure how to do that safely, replacing the battery is the easier option.

Never continue using a battery that's dented, swollen, leaking or otherwise physically damaged just because you've fitted a fresh piece of plastic around it.

How Should Spare Vape Batteries Be Carried?

Never carry loose vape batteries in a pocket or bag with metal objects.

Keys, coins and other conductive items can make contact with battery terminals and create a short circuit. Instead, put removable batteries in a dedicated plastic battery case whenever they aren't installed in a vape or charger.

This is one of the simplest battery-safety habits to follow, and one of the most important.

UK product-safety guidance specifically recommends keeping removable and spare vape batteries in a plastic case so they can't accidentally come into contact with metal objects.

Should You Buy an External Vape Battery Charger?

If you use removable batteries regularly, a dedicated charger can be a useful addition to your setup.

It allows you to charge batteries independently of the vape and, if you own spare cells, means you can have one set charging while another is in use.

Many multi-bay chargers also provide individual charging channels and useful battery information.

The important point is to use a charger designed for the particular type of lithium-ion cells you own. You can browse our range of vape battery chargers if you need one.

Whether you charge the batteries externally or inside a compatible vape, follow the device and charger manufacturers' instructions. Don't leave lithium-ion batteries charging overnight or while you're away from home.

When Should You Replace a Vape Battery?

A removable vape battery doesn't have a fixed expiry date. How quickly it wears depends on factors such as usage, charging habits, operating conditions and the particular cell.

What matters more than its age is its condition and performance.

Consider replacing a battery if:

• It has become dented, swollen, corroded or otherwise physically damaged.
• The wrap or insulator is damaged and you aren't able to replace it correctly.
• It gets unusually hot during normal use or charging.
• Its usable runtime has dropped dramatically.
• It no longer charges normally.
• The device repeatedly reports battery errors with that cell.

If something about a lithium-ion battery suddenly seems different, don't keep pushing it to see whether the problem goes away.

How Should Old Vape Batteries Be Disposed Of?

Don't put lithium-ion vape batteries in your normal household rubbish or ordinary recycling bin.

Even an old battery can retain enough energy to create a fire risk if it's crushed, punctured or short-circuited during waste handling.

Take used cells to an appropriate battery recycling point or household recycling facility. Before transporting them, keep the terminals protected and carry the batteries so that they can't come into contact with metal objects.

Would a Built-In Battery Vape Be Easier?

Possibly.

Removable batteries have some excellent advantages. You can replace a worn-out cell without replacing the entire vape, carry charged spares and potentially keep the same device in service for longer.

They also introduce an extra bit of responsibility because you're handling the battery yourself.

If you don't want to think about battery specifications, wraps, storage cases and separate chargers, there's nothing wrong with choosing a regulated vape kit with a built-in battery instead. Plug it in according to the manufacturer's instructions, charge it correctly and let the device's electronics handle the rest.

Buying Vape Batteries: Quick Checklist

Before placing an order, run through these points:

• Check exactly which battery size your vape accepts.
• Follow the vape manufacturer's battery recommendations.
• Make sure the battery's discharge capability is suitable for the device.
• Don't choose on mAh capacity alone.
• Buy genuine cells from a reputable retailer.
• For a multi-battery mod, buy matching cells together.
• Add a protective battery case if you plan to carry spares.
• Inspect every battery before using it.

Get those things right and buying vape batteries becomes much simpler. You don't need to memorise an electrical engineering textbook; you just need to resist the temptation to treat every cylindrical battery that fits in the compartment as interchangeable.

Frequently Asked Questions

The Bottom Line

The most important rule when buying vape batteries is surprisingly simple: buy the battery your vape actually requires, not the battery with the most impressive-looking numbers.

Check the device specifications, choose a genuine cell with suitable performance, use matching batteries in multi-cell mods and protect loose batteries whenever they're outside the device.

Look after them properly and removable batteries are convenient, economical and straightforward to use. Treat an unknown 18650 from the bottom of a kitchen drawer as “close enough”, on the other hand, and you've rather missed the point.