Best 21700 Batteries: (Recommendation and Things to Consider)

Published on: June 2, 2022
Written by Liam Jaxon / Fact-checked by David Rowan

What chemistries do 21700 batteries have included, what are the differences between 21700 nad 18650 batteries, are all 21700 batteries same? Such quotations people ask on search engines before purchasing a 21700 battery or planning to go to the market if they have regular purpose torchlight or small devices to use.

We think manufacturers have also admitted that the 21700 battery chargers are quite upgraded than other batteries available in the market. 

best 21700 battery

From vaping accessories to flashlight types, all devices can put it inside and charge through their USB port whether some may avoid the core battery charge. Similar to powerful Lithium-ion cells, this battery is quite popular to users for its identical dimension and size.

However, the quickest compatibility suits its upgradation a lot. Also, we are all prospective users required to keep it in mind that the batteries can be either protected or unprotected. 

Remembering such crucial features, we have enlisted some of the 21700 batteries with our experiences in detail, as well as you can find the demonstrated info and questions and answers that were raised in your mind before planning the purchase. 

21700 Batteries: Features and Specifications 

21700 batteries, a regular choice for gadgets that have higher chances of high drainage within a couple of hours. Such a high capacity battery pack, all included a high power flashlight, micro USB port and more in the toolbox that no potential can deny. Also, this is a choice for vehicles, high-end toys, electric bikes, scooters and cordless devices. 

What about dimensions? Well, most of the 21700 battery models come with a similar pattern which means 21 × 70 mm (0.827 x 2.756 inches) in width and length. So light, and the actual dimension varies from manufacturer to manufacturer ideology a little bit. However, this type of slight variation is not a big deal. 

Such a battery with advanced configuration can serve the ranges of devices between 3000 to 5000mAh. Sounds great, right? Well, if you have a flashlight with 3000 mAh capacity for night purposes, whether you are a traveler, then this is a nice selection for outdoor regulars. However, it varies relying on models, designs and the exact in-built chemistry. More or less other features you can check out,

Protected or Unprotected: 

If you are a prospective user then you better know how 21700 batteries discharge their currents. Including the materials that it is built of. The configuration is also sensitive in the case of Lithium-ion battery charging.

If the battery is filled with so many electronics in a covered position, in that case, the integrated battery management system (BMS) always occupies a huge space and is a great point to count while you turn yourself for battery purchasing from the market.

In general, BMS is a parameter enclosed in a monitor that can measure battery efficiencies like discharging current, voltage, charging current, operating temperature and more. Simply you can shut any of the features off by observing the monitor, thus your battery is protected while charging or utilizing through the gadget. 

However, the system also is applicable for cooling down the battery, reducing chances of short-circuiting and overheating time by time. As we have mentioned from our experience that the system may consume a huge space in the battery, not only managing all situations but also charging with safety. 

Terminal Type: 

Available in both button top or flat top shapes. In between these 2 battery types, distinction battery jobs and facilities are not that much hard, yet we better inform you of the method. If the end of the battery is smooth and finely shaped for iconic charging, no matter whatever people say, it is a flat-top battery.

In contrast, the end of the battery should be like the button of a button-top model whether it is a 18650 battery or a 21700 model. Though probably the 18650 ones have both button and flat shapes, the cells there create the verified distinction. However, flat top you may not use for your torchlight as if the length is shorter than it requires, and yes we know that the 1-2mm may not be the issue for 


Though it is general that a battery contains a lot of mixed chemicals inside, whether it is flat or button cell electronics consisting of batteries, it varies in IMR, IFR, ICR, INR 21700 batteries. We will give a breakdown of the abbreviation and their features and how these could be fruitful to human used gadgets. 


 LiNiMnCoO2 (Lithium Manganese Nickel) chemistry filled 21700 model batteries are known as INR batteries. High-rated currents and slightly lower capacity are the primary features. 


Features LiMn204 (Lithium Manganese Oxide) chemistry. Its nominal voltage ranges between 3.6 – 3.7 V per cell, and the highest voltage we found and testers as well as 4.2V. Though the chemistry-filled battery is large enough to deliver enough current, comparatively optimizes smaller capacity. 


Features LiFePO4 (Lithium Iron Phosphate). Charging voltage ranges between 3.5 – 3.6 V, and the nominal voltage complies similar to 3.2 – 3.3 V per cell. Having a modest capacity, IFR-contained batteries are safer than other batteries we have experienced using in electric bikes/scooters. 


LiCoO2 (Lithium Cobalt Oxide) chemistry consists and the nominal voltage ranges similar to the previous IFR battery. However, the charging voltage has been tested to be higher than 4.2V, so the highest current allowance can be controlled within moments and no overheating problem. 

How to Select a 21700 Battery? 

Some basic technical specifications let users pick the right 21700 battery from the overwhelmed market availability, as long as we have experienced these too. 

  • Voltage: 3.6V to 3.7v;
  • Amperage: 3000mAh to 5100mAh;
  • Size: 74.8mm x 21.49mm (+/- 0.3mm);
  • Weight: varies 60g to 80g;
  • Battery Type (Chemistry): LiNiMnCoO2 INR / NMC, LiCoO2 ICR, LiMn2O4 IMR, LiPo; 
  • Protected Mode.

The best models are made to be maintained by the manufacturer for such super specifications 

Best 21700 Battery (Recommendation and Things to Consider)

1. Nitecore MPB21 21700i Mini Rechargeable Battery and Flashlight 

Technical specifications

Weight 1 pound
Chemistry IMR
Discharging rate 2A
Dimension 2.1 x 0.87 x 0.87 inches
Capacity 5000mAh 
External material Plastic 

Editor’s Note 

It is an intelligent power solution for gadgets that have a capacity almost ranging between 4000 to 5000mAh. We found second to none of this version full of NL2150HPi. Either you can go with the EDC item for a great charger solution. 

The NITECORE MPB21 is an ultimate solution for the users who have approximate plural time to spend at night for any purposes that may not decrease and consume charges for longer use. Though the external part as long as it is wrapped with Plastic may not be that much safer than sorry, what do you think?

Moreover, the fact may not end up with this, as it charges a few while swapping your bucks loaded cash card at the shopping center. However, the power solution has a 2-in-1 gift for prospective users, and that is the flashlight included in the toolbox. Consisting of a capacity of 80 Lumen provides magnetic high CRI light.

In conclusion, this is a plus point. You can connect it directly with the USB to the HPi battery, sounds great, huh?  

Pros Cons 
Overcurrent protectionNothing noticeable 
A thumb-size dual functioning charger 
Compact and portable 
80 lumen of light

2. Nitecore NL2150HPi 21700 Battery and Flashlight

Technical specifications

Weight 1.1 pounds 
Chemistry IMR
Discharging rate 2A
Dimension 6.42 x 5.98 x 2.01 inches
Capacity  5,000mAh
Output Voltage4.2V1% (Battery) / 5V5% (USB)
Flashlight brightness 80 Lumen 

Editor’s Note 

As a patent product, it is really awesome to use it all the time, in fact, as a Nitecore i series, it fits in a proper way that nothing can beat it at its manufacturing style. This i-series performed much better than other i-series, we are not talking from the manufacturing manual, just our experience. 

However, with this rechargeable 21700 model, Lithium-ion reaches the next level and by how? By featuring dual output, with both secured positive and negative polarities consisting at both ends. A high energy density, including NL2140i, NL2150HPi and so on is an addition being the advanced model.

We are grateful to these groundbreaking strategies and technologies that sufficiently put efforts to make output without consuming less power in itself, and the technology has in-built internal resistance to avoid other human beings. However, we liked the included flashlight in the toolbox for a better outdoor environment experience. 

Pros Cons 
Dual polarityHefty priced 
Compatible with Nitecore i-series flashlights
Magnetic Power Bank
Includes Eco-Sensa Storage Case in the toolbox

3. Nitecore MH12S Battery and Flashlight

Technical specifications

Weight 1. 5 pound 
Chemistry Lithium-ion 
Flashlight material Aluminum 
Discharging rate 3A
Dimension 5.55 x 1 x 1 inches
Luminous Flux1800 
Finish HA III Hard Anodized
High Runtime2 hrs 30 min
Ultralow Runtime1500 hrs
Turbo Runtime45 minutes 

Editor’s Note 

Whenever we think of Nitecore, it just amazes us with a delightful light battery that is optimizable with huge competency rather than available models in the market. Though it is different from the i-series and makes it more compatible with big to mid-sized gadgets, we are sorry that it does not support tiny products like toys and similar devices. 

Instead of being overwhelmed, we put it in the third position because something that we did not like is the price. However, an included flashlight is capable of providing 1800 Luminous Flux to operate the solid darkness.

Moreover, its metallic side watch consisting of Aluminum is a great deal for longer services. In general, the optimizing Lithium-ion lets the flashlight be charged easily and provides services along with a sturdy power of about 2 hours and 30 minutes altogether. 

Pros Cons 
Available in both daily and tactical mode Hefty priced 
Metal side watch 
Easy to operate  

4. Nitecore P20iX 21700 Rechargeable Battery and Flashlight

Technical specifications

Weight 1 pound 
Chemistry INR
Discharging rate 2A
Dimension 5.57 x 1.25 x 1.25 inches
Capacity 5000mAh

Editor’s Note 

Firstly, we just want to mention why it is in the 4th position. As we know a big feature drawback can make the product being listed out on the downside. So, the feature is the discharging rate as well as the fast charging issue.

Though the capacity is 5000mAh, the battery may not take that much charge within minutes as if the battery gets overheated all of a sudden. It may occur in a bursting position. All included the battery, a torchlight weighing only 2 pounds is not a big deal, yet maximum sturdiness users can enjoy all time. 

Toolbox included torchlight consumes power to provide more than 1000 lumen for higher runtime, and we have tested around 3 hours, however, the high runtime makes it heavily tempered that shocked us. But the charging material and altogether its external material to get empowered is amazing. 

Pros Cons 
Compatible with tiny devices to mid-sized Expensive 
Compatible structure to fit inside Overheat easily 
Sturdy and dual-polarization available 

5. Fenix TK16 21700 Battery and Flashlight

Technical specifications

Weight 1 pound 
Chemistry INR
Discharging rate 2A
Dimension 5.63″ x 1.34″ x 1″
Capacity 4000mAh 
Peak Beam Distance 415 yards
Max Brightness3100 Lumen 

Editor’s Note 

Last but not least. Well, we are going to put an end to our search list for 21700 battery models. Fortunately, this one is a renowned brand yet some similar drawbacks make it compel us to put it in this position. Fenix is a well-established company for its quality battery supply, as well as torchlight manufacturing. 

The torchlight has entire Stainless Steel and is inlaid with 3x tungsten impact tips. If it gets jammed anywhere, suppose in the ice bar, it will be easier for getting out of that critical situation. Such a durable construction lets users operate in between -31 to 113 degrees. 

The battery is a C-port optimized rechargeable one that can be charged more than its capacity around 4000mAh, however, no need for an external charger. The drawback as it charges higher than the previous model rather than providing optimistic services for 

Pros Cons 
Functional tail switch Hefty-priced 
Tactical tail switch Overheated easily 
Great torchlight for single-handed operationTrouble maker 

People Also Asked 

What Is the Highest Capacity 21700 Battery?

21700 battery model, it is one of the most efficient battery models we have ever experienced. The competency to deliver power for longer services in the darkness by enlightening with torchlight is a big deal. In the battery model cases, the power serving and the capacity measures in the milliampere-hours.

The higher the measurement draws, the more a user can deal with the 21700 batteries. However, you will draw power from the battery solely relying on the user’s build, for instance, we have tested almost all of the model’s capacity ranges between 4000-5000mAh. 

Though there remain 3000mAh range batteries, we recommend not because that may not provide power as long as the 4000-5000mAh ranging batteries will. 

Are 21700 Batteries Better than 18650?

18650 batteries do not have high voltage, high capacity, high current rating and low operating temperature as long as the 21700 batteries can provide to the potential customers who love to enjoy high current rating.

Suppose, one has a large bottle of water and another has a smaller one. If they open the water bottle the limit will be higher and the water should be high to pour down. 

So, the higher the pouring amount, the higher the discharging rate. The highest current rating holder 21700 batteries has a great feature not to be overheated by the charging time. 

Does 21700 Last Longer than 18650?

The biggest difference between a 18650 battery and a 21700 battery is the size as if the size is larger than the 18650 battery models for a flashlight or tiny series of vehicles. Since 18650 batteries hold lower charges than 21700 ones with in-built power of less energy/less capacity than the 21700. 

You can also take into account the discharging and temperature for operating rate of 21700 to ensure high runtime, as well as we can think of charging very well. 

Final Thoughts 

Before utilizing 21700 battery models from any of the reputed providers, check first that the battery is in good condition or not for longer purposes. If the battery is not perfect for your devices, then the money is a waste. 

In anyways, the battery models we have picked out with our hands-on experience for you may differ from the manufacturer, PTC protection, discharging rate, voltage, current rate and more. So, better check the device you are planning to apply safer than sorry later.  

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About This Writer

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Hi, I am responsible for the 'Homeowners Power Solutions' category. My name is Liam Jaxon and a licensed technician with 7 years of experience in vehicle batteries, electrical gadgets, and home appliances. My working experience in different residential & light commercial electrical sectors and the automobile industry helped to acquire vast knowledge in this industry.

Hi, I am responsible for the 'Homeowners Power Solutions' category. My name is Liam Jaxon and a licensed technician with 7 years of experience in vehicle batteries, electrical gadgets, and home appliances. My working experience in different residential & light commercial electrical sectors and the automobile industry helped to acquire vast knowledge in this industry.

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