There are a couple of batteries that are really popular in flashlights and portable electronics in general. Right now the 18650 is probably the king with the 21700 and 26650 coming on pretty strong.
Voltage In Li-Ion Batteries
There are a bunch of numbers on the side of a Li-ion battery. The biggest one is probably the mAh number. This is talking about overall capacity of the battery. For this article we are focusing on Voltage. In most Li-ion batteries the nominal voltage is 3.7 volts, but there can be some variance depending on how much charge you have left or if it has been sitting around for awhile.
The standard 18650 cell is nominally rated at 2.8 to 4.2 Volts. There are also cells out there that will run as low as 1.5 volts. If your flashlight uses an 18650 then you should expect somewhere between 3.0 – 3.4 volts when fully charged.
18650 Minimum Voltage
The minimum voltage of most 18650 batteries is actually lower than what they claim. Most manufacturers use a cut off point of 2.6 volts which means that anything below that won’t work properly. Some companies do go down to 2.1 volts.
What is Minimum Voltage Of A Battery?
The minimum voltage of a battery is the lowest voltage at which it can deliver current. Once the battery gets low enough it will not be able to produce a current so it can not power a device. Most flashlight have a minimum voltage requirement that is higher then battery minimum voltage.
18650 Max Voltage
The maximum voltage of most 18650 batteries is usually 4.2 volts but some chargers can push them higher. Remember that these safe guards are in place to you do not burn up your batteries. Don’t go too far over the max range.
What is Max Voltage Of A Battery?
The maximum voltage is the highest amount that a battery should be charged to to stay within the safe rage of the battery.
18650 Nominal Voltage
The nominal voltage of a 18650 Li-ion battery is 3.7 volts. It’s important because many devices require a specific voltage to operate correctly. But the range of the battery voltage is usually 2.8 to 4.2.
What is Nominal Voltage Of A Battery?
The nominal voltage of a battery is the voltage at which it will deliver its rated capacity when fully charged. Nominal voltage is also the named voltage on the side of a battery. Nominal meaning named.
18650 Storage Voltage
The storage voltage for 18650 Li-ion batteries is around 50-60% of the charge. Do not store batteries at 100% charge. This is because 18650 batteries are most stable between 3.7 and 3.8 volts.
What is Storage Voltage Of A Battery?
The storage voltage of a battery is the voltage where the battery is most stable for long term storage.
18650 Voltage Conclusion
So if you made it through this you know more about voltage than most people do.
As you see as a battery drains the battery goes through a range of voltages.
This is the main reason why you do not want to mix batteries with different amounts of charge. You will create a voltage problem.
This is also why even if you could figure out how to fit a standard 1.5 volt alkaline battery into a Li-ion device you would not want to do it. Some devices are created to be able to work off of two sets of voltage. We like these since they give us flexibility.
Also even though some Li-ion batteries like 14500 and 10440 are very similarly sized as AA and AAA batteries respectively do not trade them out for one another unless the device is designed for it.
Thanks for stopping by the site and if have some other question about batteries or any of the other topics that we cover feel free to browse around.