This article tells you everything you need to know about 18650 batteries. We'll talk about different types, features, charging, lifespans, and our recommendations for batteries and chargers.
- What is an 18650?
- Recommended 18650 Batteries
- Various Battery Sizes
- Comparing 18650s to Other Common Batteries
- 18650 Terminology
- Protected vs Unprotected 18650 Batteries?
- How much power does an 18650 have?
- How many times can you recharge an 18650 or other battery?
- How frequently should I recharge my 18650?
- How do I know my 18650 is Dying?
- How can I measure the quality of an 18650 if I am unsure of the age of a battery?
- 18650 Battery Chemistry
- What are 18650 batteries used for?
- Which is the Best 18650 Battery?
- 18650 Battery Charger
- 18650 Flashlight
What is an 18650?
An 18650 is a lithium ion rechargeable battery. Their proper name is “18650 cell”. The 18650 cell has voltage of 3.7v and has between 1800mAh and 3500mAh (mili-amp-hours).
18650s may have a voltage range between 2.5 volts and 4.2 volts, or a charging voltage of 4.2 volts, but the nominal voltage of a standard 18650 is 3.7 volts.
There are two types; protected and unprotected. We absolutely recommend protected cell 18650 batteries. Protected cells include a protection circuit that stops the cell from being overcharged.
Unprotected cells can be overcharged and burst and potentially cause a fire unless there are specific electronics to protect the battery. The popular LG HG2 and INR and Samsung 25r and 35e are UNPROTECTED batteries, only use them in a device designed to use unprotected 18650s.
We also recommend you stick with high quality brand name 18650s. Knock offs may lie about high mAh (capacity).
The average 18650 battery charge time is about 4 hours. Charge time can vary with amperage and voltage of the charger and the battery type.
Recommended 18650 Batteries
|Battery Make and Type|
All are 3.7v Lithium Ion (Li-ion)
|Max Milliamp hours||Notes|
*Shop around for best price*
|Orbtronic 18650 |
|3500 mAh||Only available direct from vendor|
|Olight ORB-186C35 |
|3500 mAh||Ok price|
|Nitecore 18650 NL1835R|
|3500 mAh||Good for travel, expensive.|
Has micro-USB charger port so it can charge itself with a cable/usb port
|Panasonic NCR18650BD Button|
|3180mAh||Less expensive PROTECTED and good for high drain devices.|
|Panasonic NCR 18650 3400mAh NOT PROTECTED|
|3400 mAh||Less expensive but is |
|Panasonic NCR18650BE |
|3200 mAh||Less expensive but is|
More info on the 21700: Everything You Need to Know About the 21700 Battery
Various Battery Sizes
The following is a picture showing various battery sizes. The 18650 is 1170 cubic mm, the 14500 and AA are 700 cubic mm, the AAA is 467 cubic mm.
Note the 14500's cannot be used in all AA devices unless they support both 3.7 and 1.5 volt batteries. The 21700 at 1550 cubic mm, is larger than the 18650 battery – the 21700 and 18650 is not interchangeable.
Comparing 18650s to Other Common Batteries
A battery might say protected mode 3.7v 18650 3000 mAh low self discharge for high drain devices. What does that all these features mean?
- “protected mode” means it has an overcharge and overdraw circuit protection built in (more info below).
- “3.7v” – is the optimal or peak voltage. It will drop as you use the battery.
- “3000 mAh” measures the amp hours the battery can provide. A higher number is better. The highest realistically available on an 18650 today is about 4000 mAh, anything higher than that is marketing hype.
- “Low self discharge” is a good thing. That means it will hold a charge in storage. The less it loses in storage the more charge will be left for you to run your flashlight or other device.
- “for high drain devices” – the battery is optimized for high drain devices. These are devices that use a lot of power very fast, such as RC toy car.
Protected vs Unprotected 18650 Batteries?
Protected 18650 batteries have an electronic circuit. The circuit is embedded in the cell packaging (battery casing) that protects the cell from “over charge”, heat or “over discharge”, over current and short circuit. A 18650 protected battery is safer than an 18650 unprotected battery (less likely to overheat, burst or start on fire).
Unprotected 18650 batteries are cheaper, but we do not recommend their use. Unprotected batteries should only be used where the load/draw and charging is externally monitored and controlled. The protected batteries normally have a “button top”, but check the specifications to make sure. Generally 18650 flat top batteries do not include the protection circuit.
If any 18650 battery is damaged or looks corroded or appears to be leaking, get rid of it at a battery recycling center. Be safe.
How much power does an 18650 have?
A 3.7v a 3400mAh 18650 stores about 2 aH to max of 3.5 aH. It can store about 10 to 13 watt hours. A small air conditioning unit that can cool about 9000 BTU uses about 1100 watts per hour. So it would take more than 110 of the 18650 batteries to run the air conditioner for 1 hour.
In comparison you would need three 12v 40 amp car batteries. But 110 18650s are smaller than three car batteries.
How many times can you recharge an 18650 or other battery?
Recharge cycles vary and are limited. Think of it like a bucket. The trick is that the bucket also gets filled with a tiny bit of other junk over time, so there is less room. As the battery is reused (recharged), the battery degrades due to oxidation and electro-chemical degradation.
This happens to any rechargeable battery such as an 18650, 21700, 26650, 14500, AA, AAA or even a car battery. They can only be recharged a limited number of times.
You want to select rechargeable batteries that can be recharged many times. We specifically recommend 18650's because they have the ability to be recharged 300 to as many as 2000 times.
How frequently should I recharge my 18650?
The way you recharge your battery impacts the life of the battery. If you can measure it, you want to deplete from 3.7v down it to about 3v before you recharge. If you are not sure, use the device until it indicates a battery needs to be replaced. For a flashlight, run it till the light is dim or goes out.
A good charger will tell you the voltage of the battery so you can eventually get a sense of the life of the battery in various devices. If you recharge too frequently you “use up” the life without a return.
Some people don't let it dip below 3.3v (or even higher). Each brand and model of 18650 has different maximum cycles. So this is really a process of matching your device and usage to the life cycle of the battery.
Be aware that an 18650 battery that drops below 2.5v may “lock” the device so it can't be used. The “lock” function happens in devices such as vaping devices.
How do I know my 18650 is Dying?
Here is a list of 7 ways you can tell if you need to get rid of an 18650 (or other rechargeable battery). Look through these to determine if your 18560 is nearing the end of its life and needs to be retired:
- The battery will lose a charge on the shelf must faster than normal. It loses it's charge after a couple of days or even worse overnight.
- The battery gets hot when charging or discharging, warmer than normal.
- You have used the battery frequently over 2 to 3 years.
- The battery can hold less than 80% of its original capacity.
- Recharge time gets abnormally long.
- If there is ANY cracking or deformation in the battery.
These are the 6 signs your 18650 is dead and it is time to get a new one. If you ignore these warning signs you risk fire or even having the battery explode while being recharged.
How can I measure the quality of an 18650 if I am unsure of the age of a battery?
A trick is to buy one or two similar 18650s and mark them “new” with a Sharpe (or label them A, B, C, etc). Then use them and compare their voltage and discharge rates with the questionable 18650s.
Basically you are comparing good vs unknown this way.
You can also gauge temperature this way. Charge both the new and unknown one to see how hot the new one is compared to the one you are unsure of.
18650 Battery Chemistry
There are a number of different chemical combinations for 18650 batteries. We recommend that you focus on protected mode, the chemistry can change and isn't always reported. Many simply say Li-ION (meaning Lithium Ion).
There are actually a number of Li-Ion batteries. Here are some of the current “types”. Depending on your device type one might be better than the others.
- LiFePO4 which is Lithium iron phosphate
- also known as IFR or LFP or Li-phosphate
- LiMn2O4 which is Lithium manganese oxide
- also known as IMR or LMO or Li-manganese (high amp draw)
- LiNiMnCoO2 which is Lithium manganese nickel
- also known as INR or NMC (high amp draw)
- LiNiCoAlO2 which is Lithium nickel cobalt aluminum oxide
- also known as NCA or Li-aluminum
- LiNiCoO2 which is Lithium nickel cobalt oxide
- also known as NCO
- LiCoO2 which is Lithium cobalt oxide
- also known as ICR LCO Li-cobalt
What are 18650 batteries used for?
Flashlights, electronics, laptops, vaping and even some electric vehicles use 18650s. The Tesla uses 7180 of these batteries. Many high lumen flashlights such as the Thrunite TC15 v3 (best buy) or Fenix PD36 TAC (mo43 durable) use the 18650 or the even larger 21700 flashlights like the Nitecore P20iX a 4000 lumen flashlight.
Laptops and other electronic devices use one or more 18650’s and have recharging electronics built in. 18650's are also used in vaping (smoking) devices.
18650s are are generally Lithium Ion batteries. If you are familiar with electronics you can change out some battery packs manually, but be careful – using the wrong type of 18650 or using it incorrectly can cause a fire.
Which is the Best 18650 Battery?
Overall best 18650 battery – The Orbtronic 18650 battery. This is an 18650 3.7v 3500mAh Protected cell. This is a high drain battery. We like it but it is expensive.
Best low cost 18650 battery – The Olight ORB-186P26 18650 2600mAh 3. The Panasonic 18650 is an 18650 3.7v 2600mAh Protected cell. This battery is less expensive and slightly lower amp hours than the Orbtronic. Also, this lower cost protected 18650 battery is still more expensive than the unprotected ones.
What is the best travel 18650 battery?
Nitecore NL1834R (currently not available on Amazon but available directly from Nitecore). This is an 18650 3.7v 3400mAh protected cells with a built-in micro-USB charger. It is a few dollars more, but it allows you to charge it on the go and not have to carry a dedicated charger. The unit we have has slightly different packaging.
The cheapest decent one is the Titanium Innovations 18650 at 2600mAh. It won't last as long as the 3400 mAh Nitecore but is 1/2 the price.
What 18650 Brands are Best?
The Orbtronic, Olight, Samsung, LG, Panasonic, Surefire, ThruNite and Nitecore are good reliable 18650 rechargeable cells. Be sure to buy them from a reputable source such as BatteryJunction or direct from the manufacturer. Note: Amazon stopped selling 18650s.
We don't use the lower voltage and amperage 18650s, because they have lower amp hours and low peak wattage and lower sustained wattage.
We are willing to pay a few more dollars for the longer life, higher capacity and better quality.
18650 Battery Charger
18650 batteries are rechargeable, so you will need a good charger. We use two different 18650 chargers.
The best 18650 battery charger is the Nitecore Ci4 because it can charge pretty much anything.
Specifically, it supports: lithium ion 26650, 22650, 21700, 18650, 17670, 18490, 17500, 18350, 16340 (the 16340 is also known as RCR123), 14500, 10440 and Ni-MH and Ni-Cd AA, AAA, AAAA, C rechargeable batteries. This is our favorite charger for the 18650s.
Our runner up and “best buy” is the XTAR X4 Charger. It is a USB powered 18650 charger. It charges the batteries with any USB power source. This unit is dependent on the power source, and is a bit more expensive.
It has an LCD display for charging status. A 2amp interface yields slower charge speeds. Even the 5amp is slow because it charges at .5 amps. We have used the XTAR and Nitecore with a Nektek solar panel that has a 2amp USB interface and it has consistently worked.
The best mid priced 18650 flashlight is the Thrunite TC15 2403 lumen flashlight. It is about 1/2 the price of the PD36 and but a bit less bright. It is a GREAT buy (we have the older TN12 in emergency kits). We suggest two of these instead of one of the Fenix.
It has the following modes: Strobe (975 lumens for 226 minutes), Turbo (975 lumens for 126 minutes), High (652 lumens for 199minutes), Medium (266 lumens for 9.7 hrs), Low (19 lumens/177 hrs) and Firefly(0.29 lumens for 62 days) and it can charge itself with a USB power source. It is waterproof (IPX8) and has a max throw of 223m (764ft).
The toughest 18650 flashlight is the Fenix PD36 TAC. It is not cheap but it is durable and very bright, and has a pocket clip. The light level is 1000 lumens, and it is water resistant to IPX8. This is a “duty” quality flashlight.
The PD36 TAC offers five different brightness levels and strobe:
- Turbo: 3000 lumen – 1 hr 30 min
- High: 1000 lumen – 3 hr 15 min
- Medium: 350 Lumen (8hr 24min)
- Low 150 lumen – 18 hr 45 min
- Eco: 30 lumen – 160 hr
- STROBE (about 3hrs 2000 lumen)
It has a 300 yard or 274 meter throw.
Both the Fenix PD36 or TN15 are great LED Flashlights that use the powerful 18650 battery.
Be sure to check out our full listing of over 100 Preparedness articles, including:
- Best Rechargeable Battery and Charger (AA & AAA)
- Brightest Flashlights
- Best affordable flashlight
- 21700 vs 18650 Battery – What's the Same, What's Different
- When the Power Grid Fails – 10 Things You Need to Prepare