A few things
you need to know when purchasing a battery for your flashlight.
Li-Ion or
IMR
Li-ion is a
general term referring to any battery that uses lithium ions to create an
electrical current.
IMR
batteries are a type of li-ion battery that uses manganese as the primary
cathode material. Usually seen in flat-top cells, this chemistry is preferred
and sometimes required for high drain devices.
In plain old
English, most batteries on the market are Li-Ion cells but IMR batteries are
also popping up these days with top end, high output flashlights. These
batteries can handle a higher drain current than a Li-Ion battery.
18650,
14500, 21700, 16340 meaning.
Li-ion
batteries are named with a specific convention that tells us the exact
dimensions of the battery so you will know if it will fit into your flashlight
or not.
Li-ion
battery names break down into three parts.
The first
two numbers represent the diameter of the battery in mm. So an 18650 battery is
18 mm in diameter and a 16340 battery is 16 mm in diameter etc.
The next two
numbers represent the battery length in mm. Going back to the 18650 example,
the middle two numbers tell us the battery is 65 mm long and a 16340 battery
will be 34 mm long. – this part is important, so remember it we will come back
to it.
You’ll
notice the last number on all cylindrical batteries is always a zero. This is
because the final digit represents the shape of the battery…round like a zero.
CR123,
RCR123 both refer to a 16340 size battery with a few key differences.
A CR123 is
the non-rechargeable lithium-manganese version of a 16340 size battery while an
RCR123 is the rechargeable lithium-ion counterpart.
You may have
also noticed that two 16340 batteries is roughly the length of an 18650
battery. Many times you’ll see a flashlight support either 1x 18650 battery or
2x CR123/RCR123 batteries. Even though the 16340 batteries are slightly
narrower in diameter, the length allows for a proper contact and can be substituted.
What does
mAh mean?
Li-ion/IMR
cell available power is measured in milliamp hours (mAh). This is the battery
capacity and tells you how much charge the battery can hold.
What this
means for you is the larger the capacity of the battery, the longer runtime
you’ll get on a single charge.
Battery
Voltage
Measured in
(V) for Voltage .This is the electronic potential of the battery, or in simpler
terms, how strong the electric current is when discharged from the battery.
Most li-ion batteries have a low voltage between 3 and 3.7V.
When two
batteries are placed in a series, the voltage of each battery is combined to
calculate the new total voltage. This means that although many flashlights can
swap between 1x 18650 or 2x 16340 batteries, some devices will not be able to
handle the extra voltage. Always follow the manufacturer’s recommendations to
avoid damage to your flashlight.
Battery
Output Current
Measured in
Amps (A), the measurement of the electrical current and discharge rate. A
standard, button-top 18650 battery will usually have a discharge rate around
5A. As advances in LED technology have demanded higher and higher outputs,
nowadays you’ll see some flashlights that require a high discharge rate to
enable the brightest modes. If this is the case for your flashlight, you’ll
want to seek out batteries that meet the minimum discharge rate specified by
the manufacturer.
Now the
important bit…
Button-top,
or protected cells vs Flat-top, or unprotected cells.
Protected or
button top batteries have a small electronic circuit integrated into the cell
packaging. This circuit protects the battery against common dangers, such as
overcharge, over discharge, short circuit/over current, and temperature.
Most
protected batteries have these components:
PTC: Protect
against overheating and indirectly over current. Once cooled down or the current has reverted to normal will automatically reset.
CID or
Pressure Valve: Will disable the cell permanently if the pressure is too high
in the cell (Can be due to overcharge).
PCB: Will
protect against over discharge, over charge, and over current, depending on
design. The PCB will reset automatically or when placed in a charger.
Unprotected
flat top batteries do not have this electronic circuit in the cell
packaging. Because of this, they can
have more capacity and current capability than a protected cell. However, there
is always a danger of overheating, short circuiting, or over discharging. Unprotected batteries are also much cheaper.
Protected
button top batteries are safer to use in your flashlight. Protected batteries are less likely to ignite
and cause personal or property damage.
Unprotected
flat top batteries might be cheaper and offer you a bit more power. They
however do not offer you any protection and can cause damage to you and your
flashlight.
While some
flashlights do use unprotected flat top batteries…most likely IMR, these
flashlights have their own protection built in to prevent the above dangers
unprotected batteries pose.
Protected
batteries are safer to use in your flashlight.
Now let’s
look at the popular 18650 batteries. How do you know if it is protected or not?
Well, top
manufacturers will state it on the battery and packaging either by saying
protected or what type of protection is built in.
Next clue
will be the button top…no button top, no protection.
Next will be
the length of the battery…remember 18 is the diameter in mm, 65 is the length
in mm. If the battery is shorter than 65mm long it most probably does not have
protection.
Price…cheap
batteries usually do not have protection.
Most top
manufacturers design their flashlights to only work with the correct length of
65mm…shorter batteries will either not make contact or keep cutting out.
Some
manufacturers even add to the length to force you to just use their propriety
batteries…I am not a fan of this.
So in
closing.
Make sure
that the batteries you buy and use in your flashlight is the correct type,
protected, size, voltage and amps.
And always
follow the manufacturer’s battery recommendations.
Using a
cheap battery might lead to damage to yourself and your flashlight and most
manufacturers will not cover you for damages.
And again,
there are only a handful of battery cell manufactures out there. Most flashlight
companies use the same cells, the difference is in the protection they add to
these cells to make their batteries safe for use and extend the life cycle.
Flashlights
are not cheap. Do not go ruin your flashlight with a cheap battery.
In Afrikaans
there is a saying…
Goedkoop
koop is duur koop.
