Today, we are going to talk about the 18650/19670 rechargeable lithium battery, its uses, tech specs, best features, and uses. We also have a shopping guide for you in case you need directions on how to buy the best ones for your needs.

18650 samsung 25r 1m

The 18650/19670 are rechargeable lithium-ion batteries commonly found in home appliances, high-end toys, laptops, and similar devices that require light and powerful source of electricity. They are even often used in electric and hybrid cars.

What Should You Know About the 18650/19670 Battery?

The 19670 is the 18650 battery, but with electronic circuitry for protection against over-charging, over-discharging, high temperature and other factors that can shorten the lifespan of lithium-ion batteries or even cause them to overheat and catch fire.

So, when a battery is described as ‘19670 battery’, that is actually ‘protected 18650 battery’ and, of course, vice versa.

18650/19670 Battery: Physical Dimensions and Weight

The physical dimensions of 18650 batteries are (diameter x length) 18.6 × 65.2 mm (0.73 x 2.56 inches).

These dimensions differ slightly from model to model.

  • Some 19670 batteries are almost 68-69mm long due to added circuitry (to avoid loss in the capacity). On the other hand, some models have a standard length of 65mm with a slight loss of capacity.
  • For example, ORBTRONIC 3400mAh protected 18650 batteries use excellent Panasonic NCR18650B cells with added protection, which increases the length of the battery to 68.9 mm (+/- 0.03).

You can find the basic data for both batteries in the table at the end of the article.

18650 batteries on average weigh around 45-48g, although models with higher capacities weigh up to 55g or even slightly more.

18650 battery flat vs button top

Do I need ‘flat’ or ‘button’ type 18650 batteries?

Some batteries come with a flat top side (positive), while some models come with a button top side.

Before purchasing new batteries, be sure to check your old batteries.

How to Replace Old Rechargeable Batteries In Handheld Cordless Vacuum Cleaner

A vacuum cleaner battery is a very important part of every portable cordless vacuum cleaner. Do you want to learn more?

Check Out Our Guide on Vacuum Cleaner Battery Types and Make the Best Choices for Your Needs!

The photo above shows two different types of 18650 batteries – on the left is positive (top) side of ‘flat top’ battery and on the right side is positive (top) side of ‘button top’ battery.

  • Some 18650 batteries come with soldering tabs – when soldering tabs are removed, you can use such batteries (in most cases) as common flat top batteries.
  • But, if one needs to make a custom battery pack, batteries with soldering tabs are way to go.
  • In most cases, such batteries are made to be robust and to tolerate physical and electrical ‘abuse’ on a daily basis.

However, if you don’t have experience in working with these batteries and soldering in general, find a professional to do it for you (and no, we don’t offer that kind of service).


CR123A batteries are a group of primary and rechargeable lithium batteries. Do you want to learn more about their specs, features, and other important aspects?

Check Out Our Guide on CR123A Battery Rechargeable | Primary and Rechargeable Lithium RCR123A, 16340 Batteries!

18650/19670 Battery: Capacity and Protection

The maximum capacities of these batteries is around 3-4 Ah. Although there are batteries with higher capacities, they often come with a higher price, lower maximum allowed discharge current, lower number of charging/discharging cycles and similar.

When used in cordless vacuum cleaners, their capacity is usually around 2-2.5 Ah (2000 – 2500 mAh), but such batteries can tolerate punishment on a daily basis with higher discharging currents.

Cordless vacuum cleaners come in various forms and types. Not sure which one is the best for your needs?

Check our Guide on How to Choose the Best Cordless Vacuum Cleaner!

Due to the additional electronic circuitry, 19670 batteries (‘protected 18650’) have a lower capacity than common (unprotected) 18650 batteries. The capacity ranges usually around 2.5-3.5 Ah, rarely more.

But such batteries are much safer than 18650 batteries, which must be protected by external circuitry. When replacing old 18650/19670 batteries in your cordless vacuum cleaner, be sure to buy exactly the same batteries:

  • that have the same model (18650 or 19670);
  • feature the same or higher capacity and;
  • sport the same or a higher maximum allowed discharging current.

The 19670 (protected 18650) Typical Protection: What You Need to Know

The 19670 (protected 18650) typical protection activation levels vary from model to model, but generally, protection is activated at:

  • Over-current – activated when discharging or charging currents reach 5 to 10 Amps, sometimes even more; discharging and charging over-current levels are not always the same,
  • Over-charge – activated when cell voltage reaches 4.35V,
  • Over-discharge – activated when cell voltage drops at 2.5V,
  • Over-temperature – activated when cell temperature reaches temperatures between 70 and 90°C (between 158 and 194°F), depending on the manufacturer and battery internal construction.

Are you interested to learn more about batteries for your LED flashlights, digital thermometers, watches, clocks, toys, calculators, remote controls, and other items?

Check Out Our Guide on LR44 / AG13 / L1154 Battery Specifications, Equivalents, and Replacements!

18650/19670 Battery: Nominal Voltage and Internal Construction

All 18650 batteries are lithium-ion batteries with their voltage being around 3.6 – 3.7V and which gives them much higher energy density when compared with NiMH batteries.

The voltage difference is due to the lithium-ion battery construction. The most popular negative electrode in commercial batteries is graphite. Water-less electrolytes use various organic carbonates and salts containing lithium, while the positive electrode is generally made out of one of these materials:

  • layered oxide (such as lithium cobalt oxide or lithium manganese oxide),
  • polyanion (a type of polymer),
  • spinel (a type of mineral).

For most of the users, lithium-ion construction is not so important, but one has to know that their voltage differs slightly. If you see a lithium-ion battery with 3.6 or 3.7V, it is practically the same battery type, but made using slightly different materials.

More Things to Consider on the 18650/19670 Battery

The maximum discharge currents of typical 18650 batteries are around 10-15C (25-50 Amps), even more in short bursts.

The 18650 and 19670 batteries cost more when compared with similar NiMH and especially NiCd batteries, but they store more energy per mass and volume of the battery.

Due to their characteristics, 18650 batteries are often used in various devices and appliances ranging from flashlights, laptops, power tools, R/C toys, home appliances like cordless vacuums to various electric vehicles like golf carts and electric and hybrid cars. Since lithium batteries don’t use cadmium, mercury, and similar materials, they are much more environmentally friendly than NiCd and lead-acid batteries.

Before you buy cordless vacuum batteries, there are several things you should know about them. In this guide, you can learn how to pick the best batteries for your cordless vacuum cleaner!

Lithium batteries also have few, very important flaws: they require high-quality chargers and they cost more than NiMH and NiCd batteries.

18650 Battery Packs | Series Connection Specifications

18650 batteries are commonly used connected in series, with voltages depending on a number of used batteries:

18650 samsung 25r
  • two 18650 cells in series provide 7.2V,
  • three 18650 cells in series provide 11.1V,
  • four 18650 cells in series provide 14.4V,
  • five 18650 cells in series provide 18.5V,
  • six 18650 cells in series provide 22.2V,
  • seven 18650 cells in series provide 25.9V,
  • eight 18650 cells in series provide 29.6V etc.

What Else Should You Know About 18650 Battery Packs?

You do not use 18650 batteries connected in parallel, at least not without special protective electronics.

19670 batteries can, in theory, be connected in parallel to create a battery pack with higher capacity, BUT ONLY IF that is declared officially by their manufacturer. The reason?

Protective electronics differ greatly, some provide most basic protection, while some models provide a high degree of protection, including connecting lithium battery cells in parallel. Anyway, we haven’t yet heard of a cordless vacuum cleaner using lithium batteries connected in parallel.

One of the reasons why manufacturers of home appliances like vacuum cleaners increase voltage of battery packs is that higher voltage enables the transfer of more energy over the same wires with less energy loss due to electrical resistance in wires.

For example, if a vacuum cleaner requires 100W motor, 11.1V battery would have to provide 9 Amps, while 22.2V battery would have to provide 4.5 Amps of current.

Homasy Portable Handheld Vacuum Cleaner Cordless

Nobody wants to deal with tangled cords and heavy contraptions to clean up a mess that only requires a minute or two to address. If you have come to this realization on your own, you may already be looking for the best handheld cordless vacuum!

There are also other benefits of using higher voltages battery packs in such devices (it would be very hard to explain those benefits without too much physics, chemistry, math …).

How to Choose the Best 18650/19670 Battery?

Choosing the best 18650 battery should not be a daunting task. Choose according to your device and usage needs. For example:

High drain devices require batteries able to provide large currents.

  • So, before buying new batteries, check the maximum current drain of the device and go for batteries which can provide such current with ease – 10 Amp device will never push over the limit 20-25 Amp batteries.

Low drain devices don’t require batteries with huge maximum current, but they will operate longer with the high capacity batteries.

  • In such devices, 2500 mAh 18650 battery with 35 Amp of maximum current will not perform as good as 5000 mAh 18650 battery with 5 Amp allowed maximum current.

Standby devices (emergency cordless vacuums, for example) must operate at full power when required, but you can use them every few days, weeks or even months.

  • Such devices require batteries with a low self-discharge rate and both good capacity and good maximum allowed current.

Devices with no protective electronics require protected 18650 batteries – 19670 batteries.

  • Built-in protection of 19670 batteries will prevent overheating, overcharging, over-discharging and other ‘overs’, which can damage the battery or device and cause battery to catch fire or even explode. 18650 batteries with such protection tend to cost slightly more and have a smaller capacity, but such protection is, IMHO, worth it.

As you can see, it is very easy to pick right 18650 battery for every task 🙂

Find the most popular manufacturers and their models of 18650/19670 batteries in the following table

Photo Manufacturer Model Capacity Max Current Check Price
clearance 18650 battery
Clearance5800 mAhClearance 18650 Battery
foxnovo icr18650 3100 t
3100 mAhICR18650 3100mAh
foxnovo icr18650 t
3400 mAhICR18650 3400mAh
LG LG18650HE22500 mAh35 ALG18650HE2lg chem 18650he4 tLGLG18650HE42500 mAh30 ALG18650HE4
orbtronic 3400mah t
(Panasonic Cell)
3400 mAh10-12 AProtected NCR18650B
panasonic ncr18650b t
PanasonicNCR18650B3400 mAhNCR18650B
18650 samsung 25r t
SamsungINR18650-25R2500 mAh35 AINR18650-25R
sony us18650vtc4 t
SonyUS18650VTC42100 mAh30 AUS18650VTC4
tenergy 18650 tabs t
2600 mAhB001JDPHG4

This table could be longer, but although there are other good 18650 batteries around, batteries in the table have very good ratings from real-life users.

18650/19670 Rechargeable Batteries Bottom Line

When buying batteries (and not only batteries), read the reviews, and check average ratings since there are many FAKE batteries around. For example – simplified – if the batteries have a three-star rating because 20 users have said those batteries are fake and 20 users have said they are good, I would stay away from such batteries. On the other hand, if a battery has 4.5 stars rating because 300 users have said so, I believe that the battery is genuine.

18650/19670 Batteries FAQs

Before we depart, let’s answer some of the most frequently asked questions regarding 18650/19670 batteries. Don’t forget to use the comment section below if you have more questions for us or you want us to give you more details on these batteries.

Are 18650 batteries the same as AA batteries?

No, they are not. You cannot use 18650 batteries to replace AA batteries, single-use or rechargeable. There are voltage differences that you should take into consideration. AA batteries are smaller in size as well – 14mm diameter and 50mm height.

What is a 18650 battery?

A18650 (18mm by 65mm) battery is a lithium-ion battery. It resembles in shape AA batteries, but it is slightly larger than AA batteries.

Can you charge 18650 batteries in a regular charger?

You can charge 18650 Li-Ion battery packs in any battery charger with a Lithium-Ion battery charging feature.

How long do 18650 batteries last?

Most 18650 batteries can and should last between 300 and 500 charge cycles. As you know, a battery’s lifetime depends on how you use the device and how you charge the battery. You can extend a battery’s life significantly if you charge it regularly before it completely discharges. All batteries degrade over time. However, for a 18650, you can get up to two years of good performance before you need to replace it.

What are the best 18650 batteries on the market?

Some of the best 18650 batteries you can find on the market today come from Sony, Panasonic, Samsung, LG, Clearance, and Foxnovo.

Good luck and be very careful with lithium batteries! They are great and they store large amounts of energy in light, small packages!

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