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The 21700 batteries are high-power lithium-ion rechargeable cells used in powering flashlights, electric bikes, and other devices. Their actual name is 21700 cells, and they are named after their dimension to identify size, just like most lithium-ion cells.
Its size is 70mm in length and 21mm in diameter, and they have a voltage range of 2.5v to 4.2, but most have a voltage of 3.7v. They have a mAh that ranges between 3000mAh to 5000mAh.
Types of 21700 batteries
There are generally two types of 21700 batteries, viz protected and unprotected 21700 batteries.
Protected 21700 batteries: The protected 21700 batteries come with an electronic circuit embedded in the battery casing. This protects the battery from overcharging, overheating, over the current, short circuit, and discharge. A protected 21700 battery is safer than the unprotected one as it’s less likely to burst or cause a fire outbreak. They normally come with a button top, but it’s advisable to check the specs to be sure.
Unprotected 21700 batteries: The unprotected 21700 batteries are the ones that don’t come with the protective electronic circuit. They are usually cheaper than protected 21700 cells. Unprotected batteries can only be used when the load and the charging are monitored and controlled externally. We, however, don’t recommend the use of these batteries.
When it comes to power storage ability, An average 21700 battery with 5100mAh stores about 3 aH to 5 aH; that is, it can store 15 to 20 watts hours.
The recharge cycle of lithium-ion batteries varies, and it is limited. The more you use the battery, the more it degrades due to oxidation and electrochemical degradation, this applies to all rechargeable batteries, and 21700 cells aren’t an exception. However, 21700 batteries tend to have a long recharge cycle than other batteries. An average 21700 battery can be charged as many as 300 to 2000 times.
Below we are going to review the 5 best 21700 batteries that are available on Amazon.
The 5 Best 21700 batteries Are Reviewed Below
Here, we are going to look at the five best 21700 batteries that are available on Amazon. These high-quality and durable batteries can be used in flashlights, electric bikes, remote control, toys, and other devices. The batteries have a long recharge cycle and last for a long time when charged.
1
IMREN Rechargeable Lithium-Ion battery
The IMREN Rechargeable Lithium-Ion battery is a 3.7 volts lithium-ion rechargeable battery having a size of 21mm x 75mm and a capacity of 4500mAh. The protected 21700 battery has a button top and a maximum continuous charge of 8A.
The high-density and pollution-free rechargeable battery have a built-in HSBC interface and an attached cable that can be charged anytime, anywhere without a charger.
The IMREN lithium-ion battery features a unique hook design, has independent packaging, it’s easy to carry, and cannot be lost when hung on a backpack.
It took the high capacity 4500mAh battery 3 hours to be fully charged. Additional advantages of the battery include low self-discharge, no typical memory effect, and its life doesn’t reduce due to routine charging and discharging.
Key Features:
- A 3.7vrrechargeable battery: The IMREN 21700 battery is a 3.7v lithium-ion battery having a size of 21mm x 75mm and a capacity of 4500mAh. It has a maximum continuous discharge of 8A, a low discharge rate, high-density effect, Zero memory effect, and doesn’t cause pollution
- IMREN USB rechargeable lithium-ion battery: Thr built-in USB c interface of the battery and the attached cable can be charged anywhere at any time.
- Portable, well-packaged Packaging, and unique design: The IMREN lithium-ion battery features independent packaging, a distinctive hook design. The battery is also easy to carry and won’t be lost when hung on a bag
- High capacity: 16650mwH(4500 mA) will be fully charged in 3 hours. The battery has a low discharge rate, has zero typical memory effect, and battery life doesn’t reduce due to routine charging and recharging
- Customer service: The IMREN brand provides a 24 hours after-sales service to its customers
Specification:
- Brand name: IMREN
- Manufacturer’s name: Hunan Aimeiren New Energy Co., Lt
- Weight of item: 4.2 ounces
- Dimension of item: 3.07 x 2.36 x 1.26 inches [L x W x H]
- Voltage: 3.7 volts
- Composition of battery cell: Lithium-ion
- Unit count: 1
- Rechargeable: No
- Capacity: 5000mAh
- Size: 21mm x 75mm
- The model number of item: IMREN USB77C-50
Pros
- It is rechargeable
- It has a high capacity of about 4500mAh
- It has an independent package, and it is easy to carry
Cons
- A customer complained that the description was poor
2
Amazon Basics Alkaline Batteries
The Amazon Basics Alkaline Batteries come in a box containing 36 high-performance batteries that deliver the right amount of power to your devices while ensuring minimal efficacy.
They are made from anti-corrosion components to prevent damages caused by corrosion. They also feature leak-proof air and liquid-tight seal that ensure power is held in place until usage is needed.
The battery features an insulating ring that protects against self-discharging and short-circuiting. It also has two small holes that prevent bursting and heat build-up.
The durable batteries can be used immediately; they are unpackaged and can beater. They can be used in radios, flashlights, game controllers, clocks, toys, digital cameras, and other devices.
The Amazon basics alkaline batteries shelf is designed to last for 10 years, as they have a leak-free shelf and are made from anti-corrosion components.
However, these batteries are for single use and can’t be recharged. They are shipped in an easy easy-open package and can be used immediately or kept for later usage.
Key Features:
- A box of 36: The pack comes with 36 alkaline batteries, each of 1.5 volts made from anti-corrosion components, for a long-lasting and reliable performance across a wide range of devices.
- Compatible for many devices: The batteries are ideal for a wide range of devices including, flashlights, game controllers, television remote control, digital cameras, clocks, toys, and many other devices.
- Designed to last long: The alkaline batteries have a leak-free shelf that can last for up to 10 years. They are also made from anti-corrosion components to reduce damages caused by corrosion. All these factors make the batteries ideal for emergencies or keeping for later usage
- Easy to use: The alkaline batteries are shipped in an easy to open the package, making them very easy to use
- For single use: These batteries aren’t rechargeable. They can only be used once then get disposed of.
- Disposable batteries: The brand recommends customers check online to learn more about single used batteries disposal
Specification:
- Brand name: Amazon Basics
- Manufacturer: Amazon Basics
- Country of origin: Indonesia
- Weight of item: 1 pound
- Dimension of item: 0.41 x 0.41 x 1.75 inches [L x W x H]
- Batteries: 36 Alkaline batteries
- Rechargeable: No
- Model number: ALK AAA36FFP-U AMZ
Pros
- They are compatible with many devices
- They are made from anti-corrosion components making them less exposed to damages caused by corrosion
- They have a leak-free shelf that can last for a decade, making them ideal for later use
Cons
- They are not rechargeable
- Some customers complained that the battery was leaky
3
SNSYI 3600mAh lithium-ion battery
The SNSYI 3600mAh lithium-ion battery is high-capacity for high-lumen flashlights. The high-capacity battery lasts for a long time and can withstand more than 1500 recharge cycles.
Unlike disposable batteries, the SNSYI battery is very durable and can be used for more than 3 years, and it can be recharged using a USB charger. For more convenience, the battery can be charged with a laptop, a wall adapter, and a power bank.
The battery can power Klarus flashlights, like; Klarus XT11X, XT11, XT11GT, XT30R, XT12GT, XT2CR, AR10, G10, ST15R, ST10, 360X1, 360×3. It can also be used for streamlined flashlight types like 88083 ProTac 2L-X, 22104 SL-B26, and so on.
This 3600mAh can replace 2600mAh, and it provides more long-lasting energy and an increased usage time per time.
It features triple protection for added safety and a Japan High-Performance electric core. An additional importance of the battery is its button top which makes it a protected 21700 cell.
Its size is 18.5mm*70mm but will have a ± of 0.3mm. The brand offers a 12-month warranty.
Key Features:
- An original battery: The SNSYI 3600mAh lithium-ion battery is ideal for Klarus flashlights including, Klarus XT11X, XT11, XT11GT, XT30R, XT12GT, XT2CR, AR10, G10, ST15R, ST10, 360X1, and 360×3
- For streamlined flashlights: The rechargeable battery is also ideal for streamlined flashlights like 88083 ProTac 2L-X, 22104 SL-B26, and many others
- Can replace 2600mAh batteries: The SNSYI 3600mAh lithium-ion battery can be used to replace 2600mAh batteries; it provides more lasting energy, shines better in flashlights, and provides an increased usage per time
- High performance: The rechargeable battery features a Japan high-performance electric core and triple protection for added safety and durability.
- It’s protected: Thr battery has a button top which makes it a protected 21700 lithium aluminum battery.
- Support 1500+ recharge cycles: The SNSYI 3600mAh lithium-ion battery supports more than 1500 recharge cycles without degrading.
- Warranty Description: Thr brand offers a one year warranty to its customers
Specification:
- Brand name: SNSYI
- Manufacturer’s name: SNSYI
- Weight of item: 3.98 ounces
- Dimension of item: 2.8 x 1.6 x 0.9 inches [L x W x H]
- Power source: Battery
- Steady Voltage of battery: 3.7v
- Color: 2 pack
- The capacity of battery: 3600mAh
- Current of charging: 5V/2A （5V/1A
- Size of battery: 18.5mm*70mm (± 0.3mm)
- Charging hours: 3 to 4hours
- Recharge cycle capacity: 1500+
Pros
- The battery features over-temperature, over-current, and overcharges protection.
- The battery features short circuit and over-voltage protection, making it highly durable and safe to use
- It has more than 1500+ recharge cycles
- It can be charged using an adapter, a laptop, or a power bank
- The brand offers a one year warranty
Cons
- Some customers complained that the size is a little bit smaller
4
Samsung INR 21700-40T 4000mAh 35A Rechargeable Batteries
The Samsung INR 21700-40T 4000mAh 35A Rechargeable Battery is one of the high capacity and top-performing 21700 batteries from the Samsung brand. The high-quality rechargeable battery offers a 4,000mAh capacity and a maximum continuous discharge of 35A.
Investing in the Samsung INR 21700-40T 4000mAh 35A Rechargeable Batteries is good as it is a rechargeable battery that can withstand more than 250 recharge cycles without degrading.
Having a high discharge rate of 35A, the 21700 battery is ideal for high drain devices, and it’s a good option when making battery packs for devices requiring a minimum discharge rate.
If you’re the type that likes stocking up spare batteries for future usage, then the Samsung INR 21700-40T 4000mAh 35A Rechargeable Batteries is an ideal option for you as its shelf has a lifetime of 3+ years.
However, the Samsung 40T battery is unprotected, and it’s intended to be used in protected battery packs and not as a stand-alone product. It is advisable to use additional protection like PCB (Protection circus board) or BMS (Battery management system) to ensure safety.
Key Features:
- Samsung INR 21700-40T 4000mAh 35A Rechargeable Batteries: One of the highest performance 21700 batteries from the Samsung brand. The battery offers a 4000mAh and a 35A maximum continuous discharge.
- Rechargeable: The lithium-ion battery can be recharged using a charger. It also can withstand 250+ recharge cycles without degrading.
- High discharge rate: Having a discharge rate of 35A, the battery is ideal for devices the drain current and can also be used in making battery packs for devices requiring a minimum discharge rate
- It’s unprotected: The lithium-ion battery isn’t protected, so it has to be used in protected battery packs. It’s also recommended to use a PCB or BMS for additional protection
Specification:
- Brand: Samsung
- Manufacturer: Samsung
- Weight of item: 60 grams
- Dimension of item: 7 x 2.1 x 2.1 cm [L x W x H]
- The model number of item: INR21700-40T
- Rechargeable: yes
- Recharge cycle capacity: 250+
- The capacity of battery: 3.5 – 4 Ah
- Compatibility: Many devices
- Style: Flat top
- Capacity: 4000mAh
- Current: 35A
- Warranty: Not specified
Pros
- It has a high maximum discharge rate
- It’s ideal for devices that drain high current
Cons
- It’s not protected
5
Olight 217C50 5000mAH Customized Rechargeable Battery
The Olight 217C50 5000mAH Customized Rechargeable Battery is a high drain and high-performance rechargeable battery with a protection circuit designed specifically for the Olight flashlights.
The rechargeable battery is protected and can withstand many recharge cycles without degrading.
However, the battery is only compatible with the Olight Freyr, Olight turbo, Olight Perun, Olight Warrior turbo, Olight Odin, Olight Warrior X Pro, Olight Seeker 2, Olight Seeker 2 Pro, and the Olight M2R Pro.
The battery isn’t compatible with other Olight flashlights mentioned there. Is it compatible with non Olight Flashlights?
The battery is also customized, meaning It can’t be recharged with an external charger; rather, it is designed to charge inside the Olight flashlights using the Olight magnetic charging pad.
For additional safety, the battery has a built-in protection board that protects against overcharge, over-discharge and short circuits.
Key Features:
- A Customized design: The Olight 217c50 is designed specifically for certain Olight flashlights. These versions are the: Olight Freyr, Olight turbo, Olight Perun, Olight Warrior turbo, Olight Odin, Olight Warrior X Pro, Olight Seeker 2, Olight Seeker 2 Pro, and the Olight M2R Pro. The battery isn’t compatible with any other flashlight that’s not mentioned above.
- A high-performance battery: The 5000mAh battery is a high performance and high drain battery that’s rechargeable
- A customized charging battery: This battery cannot be charged with an external charger as it is customized. Rather, it is to be charged inside the Olight flashlights using the Olight magnetic charging pad
- Additional safety features: To ensure your safety when using the battery, it comes with a protection board that protects against short circuits, overcharge, and discharges.
Specification:
- Brand name: Olight
- Manufacturer’s name: Olight
- Weight of item: 4 ounces
- Dimension of product: 2.96 x 0.85 x 0.85 inches [L x W x H]
- Color of item: Blue
- Material: Aluminum
- Water resistance: No
- Batteries: Lithium-ion battery
- Charger: Olight Magnetic Charging Pad
Pros
- You don’t require an external charger to charge it
- The battery comes with a protection board that protects against overcharge and discharge.
Cons
- It is only compatible with some versions of Olight devices.
6
Panasonic BK-3MCCA8BA Eneloop AA 2100 Cycle Ni-MH Pre-Charged Rechargeable Batteries
The Eneloop NiMH low discharge battery features Panasonic’s advanced rechargeable battery technology that allows them to be recharged more than 2000 times.
These cells are ideal for household products like wireless gaming devices, flashlights, digital camera flash units, keyboards, and wireless mice.
There have been improvements to the conductive surface layer of the active electrode material that is made from nickel-metal hydride that helps in increasing durability and conductivity. Limiting the degradation of the conductive layer increases the recharge cycle of the Eneloop battery by up to 2100 times.
The Eneloop’s “Clean energy loop” initiative is a certainty! All Eneloop and Eneloop Pro batteries came precharged from the factory in Japan using solar energy-generated power. This process is certified twice each year by the Green Energy Clarification Center.
The Eneloop cell deliver impressive power performance and maintain a high percentage of their charge for a decade. It comes pre charged from the company and is ready to be used once outside the package. The battery also has extreme temperature performance down to about -4°F.
It also has zero memory effects. Therefore, the battery can be recharged when fully or partially discharged.
Key Features:
- Panasonic Advanced Rechargeable cell technology: The Eneloop battery uses the Panasonic Advanced rechargeable cell technology to be recharged up to 2100 times without degrading.
- Ideal for household products: The rechargeable battery is compatible with almost all household products like flashlights, digital cameras, gaming devices, keyboards, and wireless mice.
- Maintain 70% of their charge: The Eneloop rechargeable battery maintains up to 70% of its charge for 10 years when it’s not in use and stored properly.
- Greater conductivity and durability: There are improvements to the conductive surface layer of the positive electrode material that helps in producing greater conductivity and stability. It also limits the degradation of the conductive layer and increases its recharge cycle.
- Pre-charged: All Eneloop and Pro Eneloop batteries are precharged from the factory in Japan using solar energy-generated power.
- Zero memory effect: The Eneloop rechargeable battery has no memory effects, so it can be recharged when it’s fully discharged or partially discharged.
Specification:
- Brand name: Eneloop
- Manufacturer’s name: Panasonic
- Department: Household
- Weight of item: 0.496 ounces
- Dimension of product: 1.2 x 3.38 x 4.25 inches [L x W x H]
- The model number of item: BK-3MCCA8BA
- Country of origin: United States of America (USA)
- Unit count of item: 8
- Voltage: 1.2
- Battery cell composition: Ni-MH
Pros
- It features Panasonic’s advanced rechargeable cell technology that allows it to be changed several times
- It is compatible with most household devices
- It comes pre-charged from the factory, making it ideal for emergency use
- It doesn’t have a memory effect, so you can charge it when it’s completely or partially discharged.
Cons
- Some customers complained that the battery is easily exposed to corrosion
- Some customers complained that the batteries are not up to the specs
7
EEMB 3.7V Lipo Rechargeable Battery 3700mAh
The EEMB 3.7V Lipo Rechargeable Battery is a high-performance 21700 battery made from high-quality materials and high recharge cycle capacity.
The EEMB brand has been in the battery manufacturing world since 1995. Their main products are rechargeable lithium-ion batteries and primary lithium batteries. The good history of the brand has enabled it to be in all key markets in the world.
Just like most EEMB batteries, this battery is also UL certified. It comes with a date code that guarantees freshness.
The rechargeable battery doesn’t leak, has a long life cycle, and has excellent cost performance. It also features PCM protection that reduces overcharge, current, over-discharge, temperature, and short circuit.
The brand recommends keeping the cell in a 40% or 60% charged state during storage for a long time. It is also recommended that the battery be charged every three months after its receipt, and also it’s advisable to maintain the voltage between 3.7v to 4.0v.
The EEMB 3.7V Lipo Rechargeable Battery is ideal for a dashcam, blue tooth speaker, mouse, keyboard, smart home systems, cameras, e-books, monitoring devices, sleep management, pulse monitors, sleep management equipment, and other household devices
Key Features:
- Basic information of the EEMB rechargeable battery: The battery has a voltage of 3.7v, a minimum capacity of 3500mAh, an approximate weight of 74 grams, and a size of 33.5 x 96 x 10.3mm/1.32″x3.78″x0.4″ [L x W x H]
- It is certified: The cell is UN 38.3 complaint and UL certified. More than 350 EEMB batteries are also certified. To prove you can search MH20555 on UL for all the brand’s certification information
- Date code: The rechargeable battery comes with a date code that guarantees freshness and reliability.
- Durable and Reliable performance: The battery doesn’t leak; it has an excellent cost performance and long cycle life. The cell has a PCM protection function that reduces the risk of overcharge, over-discharge, over-current, over-temperature, and short circuit.
- Storage: The cell is kept at a 40% to 60% charged state during a long storage period. The brand recommends charging the battery after every 90 days and after receipt of the battery and also maintaining a good voltage of 3.7v.
- Applications: The battery is ideal for blue tooth speakers, GPS tracking devices, mouse, keyboard, smart home systems, digital cameras, PDA, e-books, blood oxygen tracking, tracking devices, pulse monitors, and other household devices.
- Customer service: You can contact the brand via Amazon message if you’ve any complain or wants to ask any question about their products.
Specification:
- Brand’s name: EEMB Co., Ltd
- Manufacturer’s name: EEMB Co., Ltd
- Weight: 74g
- Unit count: 1
- Voltage: 3.7v
- Reusability: It’s Rechargeable
- Dimension of item: 33 x 97 x 10 [L x H x W]
- Number of batteries: 1 none standard battery
- Capacity: 3700mAh
- End of current: 40 mA
- Charge temperature: 0°c – 45°C
- Discharge temperature: -20°c – 60°c
- Relative humidity of storage: 65 ± 20
Pros
- The battery is certified by UL
- It doesn’t leak, and it features an excellent cost performance
- It is compatible with most household devices
Cons
- It doesn’t come with a warranty
- The polarity is not up to standard
Buying Guide Questions
Here, we will look at some buying guide questions about 21700 batteries and cells in general. Grab a chilled juice as you go through the questions.
What is the best 21700 battery?
The Samsung INR 21700-40T 4000mAh 35A Rechargeable is one of the best 21700 batteries you can find on Amazon. Despite being an unprotected 21700, the battery has a high discharge rate of 35A and can be recharged more than 250 times without degradation.
It can be recharged using a charger, and it is ideal for devices that drain power and also good for making battery packs for devices requiring less discharge.
Are 21700 batteries better than 18650?
Yes, 21700 batteries are better than 18650 batteries because they are much larger and provide more energy and runtime. The mAh range of most 18650 batteries is between 2000 to 3500, while 21700 ranges between 3000 to 5000.
Are 21700 batteries safe?
Not all 21700 batteries are safe because some are protected, and some are not. However, most 21700 batteries include PCB protection that prevents short circuits, overcharging, and overheating. Unprotected batteries are dangerous as they lack these protective features.
How long does it take to charge a 21700 battery?
The capacity of 21700 batteries typically ranges between 3500mAh and 5000mAh. So by charging a 3500mAh battery using a 1-ampere charger, it will take 3 to 4 hours to charge. While using a 2A charger, it will take 1½ or 2 hours.
Are Golisi batteries good?
Yes. Golisi batteries are good. The battery life and the performance of the cell are incredible.
How many volts is a 21700 battery?
A 21700 battery generally has a nominal capacity ranging from 3.7v to 4.0v.
What is the strongest type of battery
Lithium-ion batteries are known to be the strongest battery. Akira Yoshino developed the sta lightweight and high-capacity batteries.
How do you charge a 21700 battery
Most 21700 batteries can be charged with a USB charger.
Conclusion
Investing in a 21700 battery is something that you won’t regret, especially if you go for the above-reviewed ones. These batteries have a high capacity, a mAh range from 3000 to 5000, most o; most are protected, durable, and made from high-quality components.
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