Batteries!

I figure that since I am unsure as to the flashaholic (one who loves flashlights) status of my viewers, and that those who are not in the know as to the vast different types of batteries out there that I would shed some light on the subject (pun intended). We will start with the smallest typical batteries found in the flashlight world and go upwards in size from there.


AAA Size Batteries

While all of the above cells look the same in terms of size, they are vastly different in terms of performance and chemistry (see the end of this post).

From left to right; Duracell 800mAh 1.2v NiMH, Duracell 1.5v Alkaline, Energizer 1.7v Lithium Primary, Ultrafire 500mAh 4.2v 10440 Lithium Ion.

A quick note on Lithium Ion batteries: Their names are indicative of their size. For example a 10440 is 10mm in diameter and 44mm in length (same size as a AAA). An 18650 is 18mm in diameter and 65mm in length. A 14500 is 14mm in diameter and 50mm in length (same size as a AA). A 16340 is 16mm in diameter and 34mm in length (same size as a CR123A).


AA Batteries

From left to right top row then bottom row; Kodak 2100mAh 1.2v NiMH, Energizer 2300mAh 1.2v NiMH, Duracell 1.5v Alkaline, Energizer 1.7v Advanced Lithium, Energizer 1.7v Ultimate Lithium, Trustfire 900mAh 4.2v 14500 Lithium Ion.


CR123A Batteries

Same order as above; Surefire 3v Lithium, Energizer 3v Lithium, Duracell 3v Lithium, Trustfire 880mAh 4.2v 16340 Lithium Ion.

Notice that this is the first size of common flashlight batteries that does not have NiMH or Alkaline batteries. CR123A cells are meant for high drain, high current lights and devices and are equipped with the better chemistries with which to do so.


18650 Batteries

18650 cells are a whole new can of worms. They are all 4.2v with Lithium Ion as their chemistry but they vary in output, capacity and abilities as you are about to see.

In the same order as the above pictures but color coded for your convenience; Samsung ICR18650-22F 2200mAh, Panasonic UR18650A 1900mAh, Panasonic UR18650FM 2600mAh, LG LGES218650 2200mAh, LG ICR18650 2200mAh, Panasonic CGR18650E 2550mAh, Angelfire 18650 3200mAh

Here is what each battery size looks like when next to one another;

Common Battery Chemistries

For this we will harp back to the first picture of AAA sized batteries for a reference;

The first Cell is a NiMH (Nickel-Metal Hydride) "AAA" cell denoted as an HR03. NiMH cells have a nominal voltage of 1.2v and is the most common rechargable AAA sized battery that can be found. They require the use of special chargers (more on that in a later post) that charge at low levels over an extended period of time. These cells can be reused and recharged until it no longer holds a charge. There is an inherent risk with NiMH chemistry that overcharging will cause a buildup of hydrogen, causing the cell to rupture. Because of this, almost all NiMH cell have a vent that this hydrogen will be emitted from in the event of serious overcharging. NiMH cells have a higher self discharge than that alkalines. Despite the higher self discharge, NiMH cells are advantageous over alkalines for high current drain applications, due in large part to their low internal resistance. For example, an alkaline battery might have a 3000mAh capacity at low current levels (200mA), but at higher current levels (1000mA or 1A) they might only have 300mAh of capacity, leading to a varying capacity related to the current draw being applied. NiMH cells will hold their full capacity even at higher current levels.

The second cell is a plain old Alkaline "AAA" cell denoted LR03. I tend to call these types of batteries alkaleaks as alkaline batteries are prone to leaking out a caustic and irritating potassium hydroxide. You see this leak as crystaline formations as the potassium hydroxide absorbs carbon dioxide from the air to form the crystal like porassium carbonate that spreads out like a fungus and is the cause of many a ruined maglite! These batteries are not rechargable and have a nominal voltage of 1.5v. Because of their chemistry, they have a gradual self discharge leading to substandard expiration dates (about 5 years.... if they don't leak).

Third is the Lithium Primary "AAA" cell denoted L92 or FR03. Lithium primaries have a lower internal resistance than NiMH leading to higher current usage. The Lithium Primary battery is composed of pile Lithium which is a metalic Lithium. Lithium cells also tend to be very lightweight as the atomic mass of one molecule of Lithium is about 7 to Nickels atomic mass of 59! Lithium Primaries are non rechargable, they do not leak, and they have a low self discharge leading long shelf lives (about 15 years!)

Lastly is the 10440 4.2v Lithiom Ion! These cells can produce tons of output and usually have very high capacities. Unlike the Lithium Primary which is composed of a metalic Lithium, Li-ion batteries are composed of an intercalated Lithium compound that allows for the higher voltage attained by Li-ions. Like NiMH batteries, Li-ions are rechargeable but you will need a different type of charger to handle the needs of the hot rod Li-ion! With power comes responsibility, and there are inherent safety risks involved with using Lithium Ion batteries. They tend to dislike high heat and have known to incinerate and explode by being driven outside of their parameters. They cannot be used safely out of a normal operating voltage range of 3v-4.2v. There are safety devices in place inside these Li-ion batteries that include; shut down seperator (for overtemperature), tear-away tab (for internal pressure), vent (for pressure relief), and a thermal interrupt (for overcurrent/overcharging situations). These safety devices occupy useful space inside the cells, add additional points of failure and irreversably disable the cell when activated. They are required because the anode (positive end) produces heat during use, while the cathode (negative end) may produce oxygen. These devices and improved electrode designs reduce/eliminate the risk of fire or explosion. Unfortunatley, these features also increase the cost compared to other battery chemistries.