18650 vs 21700 vs 26650 Batteries: Which One is Right for You?

Ever wondered what powers your , electric vehicle, or even your flashlight? The answer lies in lithium-ion batteries—small but mighty powerhouses that fuel our everyday tech. Among the most popular types are the , , and batteries, each suited for different needs. But which one should you choose? Let’s dive in and explore the pros, cons, and best applications of each.

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What is the Battery?

The battery is a widely used lithium-ion rechargeable battery, named for its size: 18mm in diameter and 65mm in length. The typically offers a capacity range of -mAh, with a nominal voltage of 3.6-3.7V. 

Its versatility has made it a favorite among lithium-ion battery manufacturers and DIY enthusiasts alike.  It is commonly found in many consumer electronics, such as laptops, flashlights, and vape devices. Thanks to its compact size and reliable performance, the has been a go-to choice for portable applications for over a decade.

Pros:

• Compact and lightweight, making it ideal for portable devices.
• Affordable and widely available, ensuring easy replacements.
• Suitable for low-to-medium power devices like laptops and flashlights.

Cons:

• Limited capacity compared to newer models, leading to shorter runtimes.
• Shorter lifespan of ~300-500 charge cycles.

Read more about the Advantages of the Battery here.

ACE Battery Cylindrical Cell

What is the Battery?

The battery is another type of lithium-ion battery, slightly larger than the , with dimensions of 21mm in diameter and 70mm in length. The boasts a capacity range of -mAh, with the same nominal voltage as its cousin. Its increased size allows for more active materials, resulting in higher capacity and better performance under load.

This battery type is designed to provide a higher energy density, which translates to more power and longer battery life. It is increasingly used in high-performance devices such as electric vehicles (EVs), power tools, and high-drain electronics.

Pros:

• Higher capacity than
• Higher energy density, making it ideal for high-drain devices.
• Longer lifespan of ~500-800 charge cycles.
• Popular in electric vehicles (e.g., Tesla Model 3  and Model Y) and power tools.

Cons:

• Larger and heavier than batteries, reducing portability, may not fit all devices
• Slightly more expensive than models.

What is the Battery?

The battery is a larger lithium-ion battery, measuring 26mm in diameter and 65mm in length. With a typical capacity range of -mAh, the is a beast when it comes to storing energy. 

With its larger size, it offers even higher capacity than both the and batteries, making it suitable for energy-intensive devices. It is commonly used in high-power applications like electric bikes, large flashlights, and off-grid solar power systems. However, their larger size has limited their adoption in mainstream consumer electronics.

Pros:

• The highest capacity, offering long runtimes for high-power devices.
• Longest lifespan of ~500- charge cycles, suitable for heavy-duty applications.
• Commonly used in e-bikes, high-lumen flashlights, and off-grid power solutions.

Cons:

• Larger size limits compatibility
• Bulkier and heavier than both and batteries.
• Higher upfront cost.
• Less common in consumer electronics

vs vs : Battery Dimensions and Physical Characteristics

FeatureDimensions (mm)18 x x x 65Weight (g)~47~70~96Compactness✅ Compact✅ Moderate❌ BulkyCapacity❌ Moderate(-mAh)✅ High(-mAh)✅✅ Very High(-mAh)Lifespan❌ Lower✅ Moderate✅✅ LongerCost✅ Affordable✅ Moderate❌ ExpensiveLifespan~300-500 cycles~500-800 cycles~500- cycles

vs vs : Different Applications of Each Battery Type

Each battery type – , , and – serves specific needs based on its size, capacity, and performance characteristics. Understanding these applications can help you decide which battery type suits your needs best. Let’s take a closer look at how each battery is used in various industries and consumer products.

Applications of the Battery

The battery is the most commonly used lithium-ion battery, found in a wide range of applications, from consumer electronics to electric vehicles. Thanks to its compact size, it is ideal for devices where space is limited but performance is still critical.

Consumer Electronics:

• Laptops and Notebooks: Many laptop batteries consist of multiple cells arranged in a pack to provide a balance of size, weight, and energy capacity.
• Power Banks: cells are often used in portable power banks to charge smartphones, tablets, and other gadgets on the go.
• Vape Devices: Vape pens and e-cigarettes use batteries because of their compact size and ability to deliver consistent power for extended usage.

Electric Vehicles (EVs) and E-Bikes:

While newer EVs and e-bikes use larger batteries, cells are still common in entry-level electric bikes and scooters due to their lower cost.

Flashlights and LED Lighting:

High-performance flashlights and other portable lighting systems often use batteries, providing reliable power in a compact form.

Applications of the Battery

The battery has gained popularity due to its higher capacity and longer lifespan, making it a better fit for applications requiring higher power output. It’s increasingly used in industries like electric vehicles, power tools, and renewable energy systems.

Electric Vehicles (EVs):

• Tesla Model 3 and other EVs: The battery has become the standard for many electric vehicle manufacturers, particularly Tesla, which uses these cells in its Model 3 for improved range and efficiency. The larger size allows for more energy storage, which is crucial for EVs' long-distance capabilities.
• E-Scooters and E-Bikes: High-performance e-bikes and scooters use batteries to ensure longer ranges, better performance, and quicker charging times.

Power Tools:

cells are becoming the standard in power tools (such as drills, saws, and lawn equipment) because they deliver higher power output and longer usage times, improving the overall efficiency of these tools.

Consumer Electronics:

The increased capacity of batteries also benefits devices like high-end laptops, power banks, and even some high-end flashlights. Devices that need extended battery life benefit from the higher energy density provided by these cells.

Renewable Energy Storage:

batteries are being used in home energy storage systems and solar power solutions. These systems need high-capacity batteries to store energy efficiently, and the offers a good balance between size and storage capacity for these applications.

Applications of the Battery

The battery is the largest of the three, offering the highest capacity and longest lifespan. It’s often used in heavy-duty applications where size and weight are less of an issue, but long-lasting power is critical.

High-Performance Flashlights and LED Lighting:

High-powered flashlights and LED lighting systems for outdoor activities, military, and industrial use often employ batteries. Their large capacity ensures longer operation at high power levels, which is essential for these demanding applications.

Camping and Emergency Lights: These batteries are ideal for long-duration, off-grid lighting solutions, especially in emergency preparedness kits.

Electric Bicycles (E-Bikes):

E-bikes and electric scooters that require more power and longer battery life rely on batteries. Their higher energy capacity ensures that these vehicles can go longer distances without recharging, making them perfect for commuters and long-distance riders.

Off-Grid Solar Systems and Energy Storage:

Off-grid energy solutions and solar power systems frequently use batteries for storing energy generated by solar panels. Their large capacity makes them ideal for storing power for homes, cabins, or RVs where access to the grid is limited or unavailable.

These batteries are also used in larger uninterruptible power supply (UPS) systems and backup power systems to ensure reliable power storage.

Electric Tools:

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Like power tools that require sustained, heavy power output, the battery is used in high-demand industrial tools and equipment. Its long cycle life and high capacity ensure that heavy machinery continues to perform efficiently.

Modeling and Robotics:

In hobbyist robotics and remote-controlled models, batteries are often used for high-powered applications, where long runtimes and strong output are necessary.

How to Choose the Right Battery: , , or ?

When deciding between the , , and batteries, there are several key factors to consider. Choosing the right battery depends largely on your specific application, required battery life, space constraints, and performance needs. Let’s break down these factors to help you make the best decision.

Consider the Size and Space Constraints

The first thing to think about when choosing a battery is the physical space available in your device or application. While all three battery types share similar cylindrical shapes, their size varies significantly.

Battery:

• Best for: Small and portable devices where space is limited.
• If you’re designing or replacing batteries in devices like laptops, vape devices, or compact flashlights, the ’s small size makes it the ideal choice.

Battery:

• Best for: Applications requiring more power but still relatively compact size.
• If your device needs more power than an can provide (such as electric vehicles, e-scooters, or high-drain tools), but you don’t want to compromise on size too much, the is a great middle ground.

Battery:

• Best for: High-capacity devices where space is less of a concern.
• If you have more space to work with, like in large flashlights, off-grid energy storage systems, or e-bikes, and you need a high-capacity, long-lasting battery, the is the way to go.

Evaluate the Capacity and Runtime

When choosing the right battery, consider how long you need the battery to last before needing a recharge. If longer battery life is essential, then larger capacity batteries like the and will be more suitable.

Battery:

• Capacity: -mAh
• Best for: Low-to-medium power applications that don’t require long runtimes.
• Ideal for devices that are used for shorter periods, such as everyday consumer electronics, where you don’t need massive battery capacity.

Battery:

• Capacity: -mAh
• Best for: High-drain devices that need a balance of size and power.
• With its higher capacity, the can power high-drain devices like electric vehicles or power tools for extended periods, making it perfect for applications where efficiency and longevity matter.

Battery:

• Capacity: -mAh
• Best for: High-power applications that need long runtimes.
• The battery offers the longest battery life, making it suitable for energy-hungry applications like e-bikes, solar power storage systems, and high-performance flashlights.

Consider Power Demand (High-Drain vs. Low-Drain Devices)

If your device requires a lot of power at once—such as in power tools or electric vehicles—you’ll want a battery with a high discharge rate. Devices with high-drain applications need a battery that can discharge power quickly without overheating or losing efficiency.

Battery:

Suitable for low-to-medium power applications that don’t have a high instantaneous power demand. Great for laptops, vape pens, and some portable lighting solutions.

Battery:

Provides better performance in high-drain applications like electric vehicles, power tools, and electric scooters. It offers a higher continuous discharge rate compared to the , making it a popular choice for devices that need sustained high power output.

Battery:

The excels in high-drain applications due to its larger size and higher capacity. It is ideal for devices such as high-power flashlights, off-grid energy storage systems, and electric bikes that need a reliable, continuous power supply for extended periods.

Think About Battery Lifespan (Cycle Life)

The lifespan of a battery is measured in charge cycles—the number of times the battery can be charged and discharged before it starts to lose its efficiency. If longevity is important to you, consider how often you expect to recharge the battery.

Battery:

Typically lasts 300-500 cycles, which is sufficient for most casual use cases, such as laptops, portable devices, or power banks.

Battery:

Has a longer lifespan of 500-800 cycles, making it a better option for high-performance devices that require consistent power over a longer period, such as electric vehicles and solar power storage.

Battery:

Known for its impressive longevity, the battery can last 500- cycles, making it the most durable of the three. This is particularly useful in heavy-duty applications like off-grid solar systems, e-bikes, and high-performance flashlights where reliability is crucial.

Factor in Price vs. Value

Price is always a consideration when choosing a battery. While batteries are typically the most affordable, the and offer higher capacity and longer lifespan, making them a better investment for certain applications.

Battery:

Best for: Budget-conscious buyers who need reliable but less powerful batteries for everyday devices like laptops, power banks, and vape pens.

Battery:

Best for: Users who need a balance of cost and performance, such as in electric vehicles or high-drain devices where both long battery life and high power output are necessary.

Battery:

Best for: Applications that require maximum power and long-term durability, but where price is not the primary concern. This includes high-power flashlights, off-grid power systems, and electric bikes.

Environmental Considerations

While all lithium-ion batteries have environmental impacts, it’s worth considering how each battery type is used and disposed of, especially for large-scale applications.

Battery:

Commonly used in consumer electronics with moderate environmental impact due to widespread use. Proper recycling is essential.

and Batteries:

Larger batteries like the and , due to their use in high-power systems like electric vehicles and off-grid energy, may have a more significant environmental footprint. However, they are more efficient and last longer, reducing the frequency of replacements.

Conclusion

Someone correct me if I'm wrong but I don't believe there is a protection circuit in existence that will allow that kind of current flow through it. Seems like the max is about 10A, maybe a little more for some on larger cells like this? Come to think of it I don't think I've even seen a with protection yet although there are with it. Samsung 40T will get you there and I see a Sony VT6A I didn't even know about...based on the performance and longevity I'd go for the Sony (in fact I think I may order a pair right now), but it looks like HKJ is showing the Samsung to perform a little better overall in his tests. Last year I got the Samsung 40 and 50 for I think $7 but right now they're about $10, as is the Sony. They are flat tops and a true flat top which is actually very slightly recessed. I just received one of the 50E-2 from Liion which was a rewrapped version with their house wrapper and a "semi button top" they added (only ordered it because they were out of the standard factory wrapped cell). That semi button top is flat and it also isn't really raised like you might expect - just enough to permit series contact.

Standard Samsungs I have measure 70.8mm, the semi-button rewrap measures 71.5mm. I have a few Sofirn cells that say mAh and 40A on the wrapper (capacity is actually more than stated and they are good cells...not sure how they've tested for current but I kinda doubt they can do 40)...those measure 71.2mm.

If somebody has a protected cell then that should surpass your length requirements by a few mm, but you'd have to be sure it would fit, and also fit in your charger. Probably easiest to alter your light by soldering a brass button to replace the driver spring, and/or swap for longer springs. I would not try to use magnets to increase the length for this kind of higher current draw. Maybe a copper slug on the bottom end if you don't mind fiddling with that every time you open the light or replace cells but that would need to fit snug and stay snug. This is also a good case for the high current beryllium springs and a bypass wire mod if the light doesn't have either of those now.

Here's the IMR link for the Sony...they make you buy two, no onesies: https://www.imrbatteries.com/sony-murata-vtc6a--mah-40a-battery/

HKJ's handy comparator (select your cells from the drop down, pick your current(s) in the checkboxes)...he has other lists for small and large cells, NiMH, etc...and you can click on each cell you choose to be taken to the individual review and data: https://lygte-info.dk/review/batteries/Commoncomparator.php

Been pondering this and I don't think I have great answers, but I do think this is worthy of doing it the right way and thinking it through carefully because we're not talking about a trivial amount of current. Are you modding/creating in a host, or altering an existing light, or just trying to save pennies on the batteries it was designed for?

Ultimately, it makes so much more sense to change the host parts in a way that they will take ordinary-length cells, rather than having to change each cell each time and attempt to get their lengths consistent.

If the tail spring board is easy to remove, totally try a longer spring there that can handle the current and retain all or most of its height while doing so over time. If that can/should be done on both ends, assuming the driver board is compatible and accessible, then do that...or perhaps a button/slug can replace a spring.

I really really do not recommend soldering cells. Spot welding is the way to go, when done correctly, but soldering adds a lot of risk especially on the negative end, and you need to add a considerable amount here, not just a little dab. If soldering is the way you want, then do it on the positive end/cap and be careful about it so you don't short, and quick about it so you don't damage seals or cause it to vent. Overheating the negative end can spell bad news for the cell either in performance or safety and that's true of these high drain cells that can take a lickin' as well as it is for ordinary lower drain cells that are somewhat more sensitive. And of course if you were to use protected cells then you wouldn't be able to solder on the negative end anyway. I've soldered buttons and blobs and tabs on dozens of NiMH and NiCd batteries over the years, but I won't solder lithium...did once, but all things considered it's not worth it to me unless it's just a blob on the top to make a small button but I haven't needed that in any of my lights in a very long time. I just wonder about all of the heat and current in this application. Plus soldering to nickel can be unreliable even with scuffing. We've seen springs literally melt from high current that was done wrong, and cells that overheated to a dangerous level through current or accidental shorts, so I wouldn't put a lot of faith in solder here even though their melting points are above what we'd expect to see.

I searched the forum for a bit but couldn't find posts that I think I'm remembering from the past about magnets and resistance/current limit. It may have been from Dale (DB Customs) in some thread, really can't remember. But I was thinking that there was a medium-level of current that was a practical limit for magnets but of course most who use them are using tiny ones as buttons/spacers, not thicker ones to fill up space and cover a larger cell. I would try some kind of slug to use as a spacer on the tail end if you don't want to modify the light itself. If nothing else, a copper pipe cap could be trimmed and filled with solder - a 1/2" is around 5/8" o.d. and I think a 3/4" will be too wide without a fair amount of sanding. I looked on Amazon to see if there were any convenient discs/slugs and there are lots of jewelry stamping blanks but most are way too thin - thickest I saw was 1/8" and they were pretty expensive for a smaller quantity of 10 or so. Washers and bushings present the problem of the spring going in the hole, so you don't get the effect you're after. If you have a very well stocked hardware store there are copper bolts that exist and you could cut the head off of one and grind it to suit....a little pricey but you could do the same with an electrical split grounding nut thingy. Heck, really for this purpose I think aluminum would be fine and if you can score a short length of 3/4" bar you could just trim pucks from it.

So the cost of parts and consumables, repeatedly for a trio of cells and more cells in the future, plus risks that are not zero...sounds cheaper and better to just spend a couple extra bucks on the ridiculously priced cells that fit the design of the light...and don't buy lights like that again. :)