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Protected vs Unprotected 18650 Li-Ion Batteries

We are you sure you’ve heard bad stories about lithium-ion batteries exploding or leaking all over the place or being dangerous? With older chemistry’s this was pretty true so that’s why battery manufacturers came up with protected and unprotected 18650 batteries.

But, with modern high-quality cells, it is less about being dangerous and more about the regulated amps. So go get some and put them in your favorite 18650 flashlight.

So is one better than the other?

Not necessarily with newer lithium-ion chemistry, the dangers are way less but there still a time you should use either one. You should learn about these so you can enjoy rechargeable batteries instead of throwing away primary batteries.

And, there’s more than one type of protection. In fact, there are three, and two of them are on almost every battery no matter what.

Li-ion Battery Safety and Protection Devices

In the United States lithium ion batteries are required to have two protection devices installed the PTC and the CID.

PTC – (positive temperature coefficient)

The PTC is a small disk of material that is used to complete the circuit. The material used in the PTC is designed to change shape if the temperature gets too high.

So if the internal resistance of the battery gets too high and the battery heats up the PTC would change shape and the circuit will break.

The PTC material will return back to its shape after it cools down. But, it is reported that there is a permanent effect and the battery isn’t ever as good as fresh batteries again. The PTC protects against external short conditions.

CID – (current interrupt device)

The CID is a small mechanism where a key piece inside of the circuit is scored so it will break easier than the other parts of the circuit.

If there is an increased internal pressure in the battery the section will break off and the circuit will no longer work. This is a permanent change in the battery and the battery will not work anymore.

The CID protects overcharged and high pressure conditions.

PCB – (protection circuit board)

The protection circuit board is really what we’re talking about when we talk about if a battery is protected or unprotected.

The PCB protects the battery from overcharging on a charger, over-discharging, and over drain. Also since it’s a circuit board it does not create any permanent damage to the battery if it’s triggered.

Since the cell protection boards are regulating a lot of the things that the batteries can do these batteries have a limited amp discharge and this affects the different devices that are used and how powerful they are.

Pros Of Protected Cells

There are a couple Pros to protected batteries.

The first is that the battery is safer by design. You’ll have way less chance of this battery having any kind of a catastrophic failure.

The second pro which we think is actually the most important one is that when the built-in protection circuits limit the amps it means that you will have a much higher capacity. Since capacity is measured in milliamp-hours and we are limiting how many amps can get out of the batter at a time we end up with a battery that is charged longer

There are some situations when you want a flashlight or another device to be able to pull as much amperage as it can. It will make the light brighter or it’ll let a motor run faster but it drains the battery way faster.

For us, we rarely need to use a flashlight at full brightness and we would rather have it last longer. So in lights where there is not the ability to dim or the electronics of the battery aren’t as good it makes sense to have a battery that limits itself so you have a higher capacity.

Pros of Unprotected Cells

The pros of unprotected batteries are that they have the ability to have a much higher amp drain.

If you want to be able to use your light or other electronic devices at their maximum you need to be able to pull as high of amps as you can.

Obviously, this will drain the battery quicker but that’s not what you’re worried about. In the case of flashlights you want it to be as bright as you can.

Aside from flashlights another popular use for unprotected cells are in Vapes. Vapes require a 10 amp to 30 amp discharge rate while most protected cells will not put out more than 6 amps.

When To Use Protected or Unprotected Cells

This was kind of covered in the pros section for each type of battery but in general, unless you have a device that you’re really trying to push to the max it makes sense to have a protected cell. So for things like laptop battery packs where you care about length of charge instead of power output protected cells are a better choice.

In most cases you are going to want to use protected cells but in these specific cases you really really want to use protected batteries.

  • Flashlights with multiple cells (unprotected are best for lights that take single cells)
  • Lights without low voltage protection built-in
  • You have a cheaper low quality light
  • If you are really inexperienced with batteries

The most typical uses of non-protected cells are in Vapes, super-bright flashlights, add other modded devices. These would be high drain IMR Batteries or INR Batteries.

How To Know If Your 18650 Battery Is Protected

There are a couple key giveaways as to whether you have a protected or unprotected battery.

The first one has to do with how smooth the wrapping is on the battery. There are two places that you should see bumps in the cell packaging if it’s a protected battery.

A protected battery requires an external connection run from the positive to the negative side of the battery so there will usually be some kind of wire going from the bottom to the top of the battery that you should be able to see and feel inside of the wrapper.

The other place is at the bottom of the battery where the electronic circuit board would be. If there’s no circuit board it will be smooth and wrap around the bottom without any bumps on the other hand the circuit board will make a less smooth wrap around the bottom of the battery.

The last way to check would be if the bottom of the battery is magnetic or not. In an unprotected battery, the bottom of the battery is metal and it will be magnetic to work in the circuit. With a protected battery the bottom will either be the circuit board which will be plastic or some manufacturers put a small metal plate or paint the bottom in a metallic color but it will not be magnetic.


Well, we hope you found what you were looking for on our site. Since batteries are a very important part of flashlights we have a lot more battery articles so if you want to learn more about primary batteries, Li-ion cells, and nickel-metal hydride batteries look around. A good place to start would be at our battery hub pages about types of batteries. If you are in the market for a flashlight check out our light buyers guides.