18650 vs 21700 - Best Vape Battery for Your Kit?
A vape battery is a key component of any vape kit. Acting as the power source, choosing the best-optimised battery for your vape device can be a daunting task.
While some vapers prefer the long-lasting nature of an internal vape battery, others like the immediacy of external battery vapes like the 18650 or the 21700, two of the most popular types. If you have a couple spare, plus what’s in the vape kit, you’ll never run low, providing the ultimate convenience!
This guide will evaluate the top external battery choices for many vapers – the 18650 and the 21700 batteries, explaining the key features of both types and the best examples to add to your vape mod.
Understanding Vape Batteries
Before diving into specifics that separate the 18650 from the 21700, first, we must explain the basics e.g. what the numbers of a vape battery mean. Put simply, a type of battery with a number like 18650 or 21700 refers to the dimensions of the battery.
As an example, the first two numbers of 21700 highlight the diameter – 21mm, while the final three numbers represent the length - 70mm. The same applies to the 18650 – 18mm is the diameter and 650mm is the length.
What Are 18650 Batteries?
18650 batteries are the most popular sought-after batteries in vaping discussion. Known for their reliability and availability, these batteries are adored by those who seek greater control over how and when they vape. Often found in singular and dual external battery vape devices, the low price is a unique feature.
Rechargeable and available from several household brands such as EFEST in the UK, their versatility means vapers can enjoy long-lasting power. Capacities can range from anywhere between 1500mAh to 5000mAh.
A higher capacity simply means the longer the battery will last. The abbreviation of mAh, often seen in vape product descriptions, refers to milliamp.
Another important element is the discharge rate, a key factor when buying an 18650 or any other type of vape battery. Often ranging between 10A and 45A, discharge refers to how quickly a battery uses energy. More power and a higher number decrease battery longevity at a faster rate.
Benefits of Dual 18650 Batteries
The main beneficiary of dual 18650 batteries is Sub-Ohm vapers. These aficionados of vaping love to maximise the power of their favourite customisable vape kit, hoping to create:
High levels of flavour
A warmer vape
Large cloud production
To achieve this feat, they need a low nicotine level e-liquid from a higher VG vape juice. The Vegetable Glycerine (VG) acts as the base to produce the larger clouds. To support this vape juice type, the vape device will need to generate more power, thus requiring a more powerful battery source.
An internal battery vape mod provides clear benefits. It can potentially generate the same amount of power as a dual 18650 battery mod and save money because you do not need to invest time and money in purchasing external batteries. However, you need to have a USB charger, accessibility to a USB port to plug in the device and spare time to wait around for a recharge.
How long does an internal battery vape need to charge with a USB? Depending on the vape manufacturer and type of battery they install, it can take anywhere from 45 minutes or sometimes hours for a full recharge from top kits such as the Innokin Coolfire PZPulse and the Vaporesso Armour G.
For those using mods that support dual 18650 batteries, the benefits include extended battery life and increased power output. More importantly, it means added convenience in contrast to internal battery vaping.
This setup is ideal for heavy vapers who need their device to last throughout the day without recharging – for easy vaping on the move.
Vape Battery Advantages: 18650s
18650s are also lighter than 21700s
Cross-compatibility with more devices
One of the cheapest costs for external batteries
Shorter charge time
Best 18650 Vape Battery for 2025
So, is it better to opt for what the industry regards as reliable with an 18650 battery instead of the new sheriff in town – the 21700? With 18650, brands like Molicel showcase why 18650 is so popular. Check out our top picks for this year:
1.Sinowatt 18650 30SP Battery 3000mAh 15A – Sinowatt is a fast-emerging manufacturer of top-quality batteries. This 18650 battery has a surprisingly low discharge rate, meaning even with plenty of power at 3000mAh, the lower discharge rate means it should last longer than the typical 18650s.
2.EFEST 18650 Battery 3000mah 35A – Chinese brand EFEST makes premium batteries for vaping on the go without hassle. Their 3000mAh battery capacity accessory is plenty to keep your Sub-Ohm vape kit performing to a very high level at a high wattage output!
3.MoliCel 18650 Battery 2800mAh 28A – Finally, we have the 2800mAh battery capacity model from Molicel with a 28A discharge rate. Consistent and long-lasting, they provide excellent value for enthusiasts of cloud chasing.
Exploring 21700 Batteries
The 21700 batteries are a newer addition to the vaping market, offering crystal clear advantages over their 18650 counterparts.
Ranging from 2500mAh to 5000mAh, this means longer use and less need to recharge the batteries through an external charger, leaving more time vape as required.
Better yet, they can provide a larger output of wattage. Therefore, if you want to utilise all the power of your vape kit (some can vape above 200W), a dual 21700 mod will offer loads of power and endurance.
Features of 21700 Batteries
With 21700 batteries, they are a little different in size and weight. As we mentioned earlier, as the number represents dimensions, this demonstrates they are slightly bigger in size than the 18650s. Therefore, they will not fill all devices, so always read the product description of your external vape kit to see which batteries they require.
However, do not let the additional size and weight put you off. Many cloud chasers turn to these in times of need!
Vape Battery Advantages: 21700s
Higher energy density
Last longer with more charge
Greater capacity (max of 5000mAh compared to 3500mAh for 18650s)
Less prone to short circuit issues
Compatibility: 21700 batteries might not fit in devices that use 18650 batteries
Best 21700 Vape Battery for 2025
There are lots of great choices for 2025 vaping with a 21700 battery. Even with higher power and faster discharge rates, the technology is always evolving with 21700 batteries, meaning they are more compact than the first models accessible to vapers. Check out some of the top brands for 2025 below:
1.Vapcell P42A 21700 Battery (4200mAh) - Huge battery capacity on this accessory from Vapcell - a leading brand for vape mod kits. With a capacity of 4200mAh, following a full charge, it is more than enough for a day of Sub-Ohm vaping.
2.Fogstar Energy 4000 21700 Battery – Fogstar are a leading manufacturer of batteries and the go-to for many vapers. This ‘Energy’ named battery is perfect for singular vape mods, as it offers plenty of power in a convenient format.
3.Molicel P42A 21700 Battery – Molicel is a powerful name and type of battery to add to your vape kit. Their P42A is high-performing and built to last.
Are the 18650s Better Than the 21700s?
There are a few key differences between the classic 18650 batteries that many love and the fashionable 21700s (you can find vape kits requiring singular and dual 18650s or 21700s).
While the 21700s have more capacity, this also means they reduce power at a faster rate, especially when used with larger wattage devices for Sub-Ohm vaping. For lower resistance coils, at Sub-Ohm levels of power, 21700s will perform better than 18650s.
Safety Tips for Using Vape Batteries
Safety should be the number one priority when using any e-cigarette. Below, you can find some useful tips to prevent accidents from occurring:
Always store batteries in a case or protective sleeve to prevent accidental contact with metal objects.
Avoid exposing batteries to extreme temperatures.
Use a charger specifically designed for your type of battery.
Do not leave charging batteries unattended.
Regularly inspect batteries for any signs of damage or wear.
Replace batteries at the first sign of any issues, such as overheating or physical damage.
The Right Choice for You: 18650 or 21700?
Ultimately, the decision between 18650 and 21700 batteries depends on your specific vaping needs.
Choosing the correct vape battery to match your chosen vape device is crucial for both performance and safety. Now that our guide has explained the key differences and benefits between 18650 and 21700 batteries, you can make the best decision that suits your vaping style.
If you seek a battery that takes less time to charge and has a higher density, which means it can last for longer and has a larger capacity, go for the 21700. Although it might cost slightly more, the added expense is worth it in the long run. However, remember 21700 batteries are slightly bigger and heavier, and do not fit all devices.
We advise checking the device you are after and weighing up the pros and cons before making your final decision. Regardless of which you select, an external battery is the way to go if you want to save time waiting for the device to charge while out and about.
Simply swap for a new external rechargeable battery so you can vape when the moment arises. Better yet – you can always carry an extra couple after charging at home in the evening. That way, you will never be low on power!
Whether you are a vaping novice or an experienced user, selecting the right battery will enhance your vaping journey. For any further questions about vape batteries, do not hesitate to reach out to our team, who are more than happy to help you find the best external vape battery for your vape kit.