I. Battery Basics
The Science of Batteries
Batteries convert chemical energy into electricity by using one or more galvanic cells. Within each cell are two electrodes, each made from a different type of metal (or metallic compound) and an electrolyte solution. The positively charged electrode is called a cathode. The negatively charged electrode is called an anode. The electrolyte solution conducts the electric current inside the cell.
When you switch on a battery-powered device, such as a flashlight, electrons (negatively charged subatomic particles) begin to move quickly within each battery. Metal ions from the anode are dissolved into the electrolyte solution while hydrogen molecules from the electrolyte are deposited onto the cathode. Switching on the flashlight amounts to completing an electric circuit (pathway) that includes the battery terminals and the bulb. The current circulates through the battery and the flashlight, making the bulb work.
When the anode has been fully dissolved or the cathode is fully reduced, the battery is considered to be discharged. Until this happens, a battery's active life depends on the amount of energy required to power the device as well as the type of metals used for its electrodes. Every metal or metallic compound has an electromotive force, which is the ability of the metal to gain or lose electrons in relation to another type of metal. The large the difference between the electromotive forces of the anode and cathode, the greater the amount of energy will be produced by the cell.
|Anode Materials||Cathode Materials|
|(Listed from worst [most positive] to best [most negative])||(Listed from best [most positive] to worst [most negative])|
Since a battery is one or more galvanic cells connected in series or in parallel, batteries can be made with almost any current at almost any voltage level. A battery composed of two 1.5V cells will produce 3V. A typical 9V battery is simply six 1.5V cells connected in a series. This type of series battery, however, will produce a current equivalent to just one of the galvanic cells.
A battery composed of two 1.5V cells connected in parallel will still produce a voltage of 1.5V but the current can be double the current of just one cell thereby providing a current twice as long as a single cell.
Basic Battery Terminology
Disposable or Primary are terms used for the most common type of battery for every day use. These batteries are designed to be cycled (fully discharged) only once and then discarded.
Rechargeable or Secondary are terms used most often with specific devices such as laptop computers, answering machines or cell phones. These batteries can be re-charged and re-used when the chemical charge is exhausted. How? The electrodes contain chemicals that can be revived by reversing the electrochemical reaction that produces power. When such a battery is placed into a recharging unit, the charger sends a reverse current through the electrodes. The reverse current is delivered at a higher voltage, which is used to re-form the chemicals at each electrode. Once the battery voltage is increased to its charged state, it can be removed and used again.
Wet Cell is a term that describes the batterys electrolyte fluid which, in this case is thinner and more liquid in form. Wet cell batteries are often sensitive to the batterys orientation and if positioned incorrectly, may not be able to produce a current if gas pockets form around an electrode. Vehicle batteries are almost always wet cells.
Dry Cell is a term that describes a more solid, paste-like or powdery electrolyte material in a battery. Orientation is not a factor in dry cell batteries.
Acid batteries get their name because of the type of electrolyte used in their construction. Acid-based batteries most often use sulphuric acid as the major component and are most often found used in vehicles.
Types of Disposable Batteries
Certain disposable batteries are best suited for specific applications. These are the following types:
- Alkaline (aka Zinc-Manganese Dioxide) batteries comprise about 30% of all household batteries in the world. This type of battery has electrodes made of zinc and manganese-oxide. The names refer to the strong alkali solution, potassium hydroxide, used in them as an electrolyte. Pros: They are affordable, have a long shelf-life, and are about five times more useful life than Carbon-zinc batteries. Cons: The energy supply can be drained quickly in high-power devices.
- Carbon-zinc batteries, also called standard carbon batteries, have electrodes made of zinc and carbon. An acidic paste between the electrodes serves as the electrolyte. Pros: Least expensive and have a long shelf life. Cons: Poor performance at lower temperatures, and performance diminishes as power drains from the battery. They have a propensity to leak because of the casing and can ruin the devices they are in.
Note: Household items such as flashlights, radios, and remote controls typically use alkaline or carbon-zinc batteries. Because they last from five to eight times longer, alkaline batteries may be more economical than carbon-zinc batteries for devices that require high amounts of currents.
- Lithium batteries have lithium metal anodes and produce more than twice the voltage of an alkaline cell. They are used in cameras, pacemakers, watches, and calculators because they have a very long service life in these low power devices. Lithium batteries weigh less than alkalines, which saves you 1 ounce for every 4 AA batteries. Pros: Lithium batteries provide a high power output, long shelf-life, and low temperature performance. They are small and light weight. Cons: High cost and the energy supply can be drained quickly in high-energy devices.
- Air batteries have a zinc anode and a potassium hydroxide electrolyte. Because an air battery requires oxygen from the air or atmosphere for its electrochemical reaction to occur, it can operate only where the atmosphere is controlled. Air batteries are commonly used in hearing aids because the humidity and temperature within the ear canal remain constant. Pros: High energy output and long service life. They can only operate in a controlled atmosphere, and provide low power. Cons: Only designed for very small devices and usually are button sized.
Benefits of using disposable batteries:
- Industry standards guarantee dependability
- Affordable, usually costing less than $1 each
- Widely obtainable at a variety of retail locations
- Long shelf-life (the ability to keep their energy-producing capacity for years, if unused)
Drawbacks of using disposable batteries:
- Despite their long shelf-life, they have a rather short ACTIVE life.
- Long-term costs. Over the course of you lifetime, you could spend hundreds and hundreds of dollars replacing these batteries in all your devices.
Note: Forget the hype about Super Titanium, E3 or any other new and over-advertised alkaline technology. They cost more and once used, still go in the garbage. Slightly longer active life is not offset by the cost and in the end, the battery companies are just making a lot of money off their strategic ad campaigns.
Types of Rechargeable Batteries
Not all disposable batteries are created equal. These are the following types:
- Nickel-cadmium batteries, also called Ni-Cad batteries, have electrodes made of nickel-hydroxide and cadmium and use potassium hydroxide as the electrolyte. They are less expensive than NiMH and hold their charge longer. Pros: Inexpensive, long-lasting, and strong performance at high temperatures. NiCd batteries use Cadmium, a highly toxic heavy metal that can damage the environment if not disposed of properly. Cons: Low energy capacity, toxic, and decline quickly with use.
- Rechargeable Alkaline Batteries are made only by Rayovac and marketed to be rechargeable 25 times or more. Pros: The manufacturer states that its batteries do not suffer from memory loss that NiCd batteries do and that the shelf life is as long as disposable alkaline batteries. Cons: Unknown at this time.
- Nickle-metal-hydride (Ni-MH) batteries use a nickle-hydroxide cathode, an alloy of a rare earth metal (M) with nickel for its anode and a potassium hydroxide solution for the electrolyte. These are a good replacement for alkalines. They are more expensive and have a shorter service life than NiCd. Pros: They can store large amounts of energy. Cons: Self-discharge quickly, and easily damaged by overcharging.
- Lithium-ion batteries use an anode made of any one of a number of carbon-based materials. The cathode is made of a cobalt, manganese, or nickel oxide that includes lithium. They require special circuitry to help keep them from exploding, which is why general-purpose Li-ion cells are not commercially available in standard sizes like AA , C or D cell. Pros: Lithium offers the highest energy-producing potential at the lightest weight. Cons: They have a high cost, diminishing performance as power drains from the battery, and can explode if misused.
- Nickel-Iron (Ni-I) are sometimes called the Edison battery and are much less expensive to build and to dispose of than nickel-cadmium cells. They are widely used in industrial settings and in eastern Europe where iron and nickel are readily available and inexpensive. Pros: The cells are rugged and reliable. Cons: They do not charge very well.
Benefits of using rechargeable batteries:
- Compared to non-rechargeable carbon zinc or alkaline batteries, rechargeable batteries last longer
- Less expensive in the long run usually designed to be recycled anywhere from 100 to 1000 times!
- More environmentally friendly less waste created by reusing
Drawbacks of using rechargeable batteries:
- More expensive initially
- Less widely available
II. Battery Size
Our AA Battery Doctrine
Whether you chose disposable or rechargeable batteries, we strongly support battery size standardization for practicality, and choose AA as the most universal size. By compiling gear powered exclusively by AA batteries, a soldier can triage his/her gear and replace any/all batteries more quickly and efficiently. All battery-powered gear on our site follows this standardization doctrine.
Compare the size, weight, and capacity of the standard batteries listed in Table 2.1. Relative to their weight, AA batteries have the best characteristics when compared to these other battery sizes. Also, there are adapters that hold AA batteries which enable you to use them in devices that normally require larger batteries. It is estimated that 90% of portable, battery-operated devices require AA, C, or D battery sizes.
|AAAA||1.5||595||1.6 (42.5)||0.32 (8.3)||6.5|
|AAA||1.5||1125||1.75 (44.5)||0.41 (10.5)||11.5|
|AA||1.5||2600||1.98 (50.5)||0.57 (14.5)||23|
|1.75||2900||1.98 (50.5)||0.57 (14.5)||14.5|
|C||1.5||8350||1.96 (50.0)||1.03 (26.2)||66.2|
|D||1.5||18000||2.42 (61.5)||1.34 (34.2)||141.9|
|F||1.5||26000||3.45 (87.8)||1.27 (32.2)||201|
|N||1.5||1000||1.18 (30.2)||0.47 (12.0)||9|
|9V||9||595||1.9 (48.5)||1.04 (26.5) x 0.68 (17.5)||45.6||Contains 6 AAAA|
|Lantern||6||26000||4.52 (115)||2.62 (66.7)||885||Contains 4 F cells|
|MN 21/23||12||40||1.12 (28.5)||0.40 (10.3)||7.5||Contains 8 LR932|
|123A||3||1300||1.35 (34.5)||0.66 (17.0)||15.5|
III. Battery Advice
Because batteries are so common, we may forget that they are self-contained chemical reactors and that their contents can be harmful under certain circumstances. The chemicals that provide the battery's energy source are safely sealed within a metal or plastic container at the factory. Over time, however, battery casings may develop leaks because of abuse or degradation. Leaking batteries should never be used and should be discarded as soon as proper disposal can be arranged.
Certain types of batteries may explode if they overheat. To protect yourself, never recharge a disposable battery. Batteries should never be exposed to open flames, disposed of in fires of incinerators, or stored in areas where the temperature may exceed 37C. Batteries should likewise be kept free from moisture, which may cause a metal battery casing to corrode and leak. You should never carry a battery loose in your pocket, as contact with coins or other metal objects may cause the battery to short-circuit and overheat.
If a manufacturer recommends a particular type of battery for a battery operated device, never use any other type of battery. Never Mix batteries from different manufacturers. Never mix batteries of different capacities. Never mix batteries of different chemistries. i.e. NiCD, NiMH, Lithium,etc.
Batteries that are no longer useful should not be stored together. While they may lack sufficient charge to power their intended devices, drained batteries nonetheless retain some energy. If they come into contact with one another, they could generate enough heat to become a fire hazard.
Newer NiMH battery chargers are designed to specifically charge NiMH and NiCad chemistries. However most of the older NiCad chargers were not designed to charge any other battery chemistries such as NiMH since they were unavailable at that time these chargers were designed. That is why many of the newer NiMH/NiCad chargers are capable of automatically charging both types, while others have a switch.
Batteries Storage Tips for Field Use
Keep batteries stored in a cool place (like your refrigerator) until you're ready to use them. Warm up only as many as you'll need. Lithium batteries won't need warming up unless they've been in temperatures below -20F. Protect dry cell batteries by keeping them out of the cold and wind. Cover them with your clothing. Put them in a vehicle or common shelter when possible. Sheltering batteries behind a wind break is better than leaving them out in the open. Putting them next to your body is best of all. Never stow batteries next to a heater or stove. That's too much warmth for most batteries and they could vent or rupture.
Do not throw away dead or weak batteries. Heat can speed-up any remaining chemical reaction. Small batteries can gain life by warming them in your arm pit or between your legs. A larger battery can gain life by sleeping with the battery next to the body. Additional life can also be gained by placing batteries in the sun.
Keep spare batteries handy so you can make a switch when the ones in your gear start to fade. When you remove batteries from your gear, put them in an inside shirt pocket to warm up. After a while, they'll regain their punch.
If you won't be using your gear right away, don't install the batteries. Keep them warm as long as you can. If you warm batteries in a heated place, watch for sweating. Wipe off any moisture or it will freeze when you go back into the cold. Finally, if your gear has plastic pins in the battery compartment, take care when installing the battery. Cold pins become brittle. They'll break if handled too roughly.
AA batteries of different chemistry are not compatible. Also, if you replace one battery, replace them all. A weak battery not pulling its load will cause the others to drain more rapidly.
Common to all types of rechargeable batteries is a thing called "self discharge" where the battery actually loses power even though the device it's in is turned off. We don't know the exact rate of self discharge (it varies between capacity and battery chemistry) - but it is something you should be aware of. If you leave your camera sitting in a bag for long periods of time the NiMH batteries will not have much power left.
Fast vs. Standard Chargers
There are some factors to consider when comparing fast charging versus standard charging units. A typical NiMH fast charger will have a charge time of 15-60 minutes. While a standard charger will have a charge time of 60-180 minutes. Quality is important since we have heard of units that actually fry the batteries instead of charging them. For this reason, we suggest a name brand unit. Otherwise, it boils down to your specific needs: do you prefer not needing an AC adapter? Do you require a 12V input for charging off your cars cigarette lighter? These features may be more important than the charging speed.
Basically, fast charging units supply the batteries with more power at higher rates. The batteries thereby charge faster but may suffer more wear and tear. On the other hand, standard charging units charge batteries with less power at slower rates, thereby causing less wear and tear on the batteries. In the end, there is no noticeable difference in the battery performance. Nor can we determine a difference in the number of charges you can expect from each unit.
IV. Our Recommendations
We strongly encourage the exclusive use of Lithium batteries for gear that has a low power draw (like LED flashlights). This will reduce the number of times you'll have to change batteries. Lithium batteries are: much lighter; last longer; more resistant to cold; have better shelf-life; and withstand heavier current draws. They are five times as expensive, but when you really need them, believe us, it will be worth it. Alkaline batteries are fine and dandy for home use, but switching to Lithium before taking your light source to the field will increase the battery life10-25%.
We encourage the exclusive use of rechargeable nickel-metal-hydride (Ni-MH) batteries for use in your high power draw devices. This will reduce the number of batteries you'll be throwing in the trash and save you money. Most new battery chargers can use Ni-MH or Ni-Cad batteries interchangeably. Primary batteries, secondary Ni-Cad, or secondary alkaline batteries are good enough for home use, but switching to Ni-MH before taking your GPS to the field will increase the battery life 5-15%.
|Life Cycles||Charge Times
|Operating Temperatures||Shelf Life||Price
|Primary Batteries||Alkaline||1.5||2600||23||N/A||N/A||-18°C to 55°C
(0°F to 131°F)
|Lithium||1.75||2900||13-15||N/A||N/A||-40°C to 40°C
(-40°F to 140°F)
|Carbon-Zinc||1.5||950||15-18||N/A||N/A||-18°C to 55°C
(0°F to 131°F)
|Secondary Batteries||Rechareable Alkaline||1.5||2000||20-22g||25-500||3-10||-18°C to 55°C
(0°F to 131°F)
|Nickel-cadmium||1.2||600-800||18-24||600-900||16||-20°C to 45°C
(-4°F to 113°F)
|Nickel-metal-hydride||1.2||1600-2500||14-30||500-1000||1-3||0°C to 50°C
(32°F to 122°F)
Ideally, we recommend a AA NiMH fast charger with folding prongs on the back (often called a travel charger) capable of handling 120-240V (for international charging) and a 12V input. This will allow you to charge from a wall outlet in almost any country or from a vehicle, with the least amount of adapters. We also recommend smart charger features such as trickle charge and overcharge protection. This will keep your batteries fully charged when left charging and will keep the batteries from getting fried.
New M1 Nanophosphate batteries recharge in minutes instead of an hour, and lasts for decades instead of a couple of years. Traditional lithium-ion batteries use bits of metal oxide to store energy, but it takes a while for lithium ions to diffuse into these relatively large particles. The M1 developed by A123Systems, charges faster by instead using tiny specs of iron phosphate to quickly absorb ions. The easier movement of ions means less wear and tear and a longer lifetime for the battery. Plus, it's less prone to exploding. While charging, standard lithium-ion batteries heat up and release oxygen - fuel for fire - at around 300F. The M1's iron phosphate has been tested at about 480 (far hotter than the batteries are likely to get) without shedding any oxygen. M1's are currently used in power tools and hybrid/electric vehicles. There are currently no batteries available for consumer electronic devices.
In this modern day of portable electronic devices, the biggest limiting factor is battery life. As the field of material engineering continues to grow, so will the limits of battery life. Check this site often for updates to battery life technology.
V. The Power Frontier
Panasonic has come out with a new bread of disposable batteries called Oxyrides. They deliver twice the performance of high-end alkalines for the same price. AA and AAA rechargeables are still the most cost-effective way to power many such devices, but lots of people use disposables anyway, perhaps because of the high initial investment that rechargeables require.
Panasonic says it uses a patented process and a combination of new and improved electrolytes to manufacture the new AA and AAA cells. After eight years in development, they finally reached store shelves in Japan in 2007. Oxyrides face some competition in the disposable arena from long-lived AA and AAA lithium disposable batteries. But these batteries also cost about three times as much as alkalines. Given their relatively low price and their sizable power boost. Oxyrides should hold greater appeal for many battery buyers. There's one slight catch: At least for now, you can get the batteries only from Panasonic; the company has no plans at present to license its technology to others.
Capacitors are better than batteries in almost every way, except in the amount of energy they store. Unlike batteries, which produce voltage from a chemical reaction, capacitors store electricity between a pair of metal plates. The larger the area of the plates, and the smaller the space between them, the more energy a capacitor can hold. Recent experiments to increase the surface area of the plates by covering the plates with millions of microscopic filaments known as carbon nanotubes. With nanotubes it is possible to store an amount of energy that is comparable to what batteries store.
A capacitor-powered gadget could be charged in minutes or seconds instead of hours. And since capacitors can be reused indefinitely, environmental waste from discarded batteries would become a thing of the past.
Delta Gear predicts that battery free bliss will be here by 2015.
Germs & Viruses
MIT researchers are developing a new breed of lithium-ion battery that's razor-thin, transparent and more potent than current power cells. This battery looks like a piece of tape. A light, see-through battery could open the door to less-cumbersome computers, MP3 players and other gadgets. The secret to its slimness... a virus called M13. Most batteries store energy in electrodes made of bulky carbon or metal. To cut weight and increase power, a virus is used as a cathode to attract metal ions and then bathed them in a solution of cobalt oxide and gold, metals known for their superior energy-storage properties. Coating the viruses in an iron phosphate before attaching to carbon nanotubes onto a charged polymer film created an electrode 40 times as thin as a human hair. Tests conducted earlier this year showed that it stored three times the energy of a conventional electrode. The new battery is currently in the prototype stage, but expect the technology to go commercial by 2018.