Spare batteries for your electronics devices are extremely important to have. Without them your flashlight is only good for so many hours, your radio won't hold out, and you can forget about using your GPS to quickly guide yourself out of a bad situation. Batteries are definitely required if you want to have a few electronic gadgets with you. A clever survivor will form a strategy to maximize the effectiveness of his batteries and also choose batteries that last as long as possible.
Your battery strategy begins before you buy the devices that will need batteries. By purchasing a radio, flashlight, and GPS that all use the same type of battery you will have more options when it comes to maintaining the devices. You will also make things simpler for yourself by only needing to purchase and carry a single type of battery. You should also consider the merits of the different size and shapes. AA batteries are extremely common and relatively cheap. CR123s provide the most power for their size, but cost more and are less common.
It is generally not wise to plan on scavenging batteries, as they will likely be the first items sold out in a disaster. It is more prudent to store the batteries that one may need in a disaster, especially given the long shelf life of typical varieties. However, if scavenging is absolutely necessary, AA's are quite common.
- Traditional Alkaline - Alkaline batteries have been around for year, they are cheap, reliable and easy to come by. They do suffer from poor performance in cold weather, however, and do not store particularly well.
- Lithium Batteries - Lithium batteries have a longer shelf-life, longer service life, better performance under extreme temperatures, and can be lighter, but they are more expensive and slightly less common.
- Lithium Ion - Lithium ion batteries have the highest energy density of the available rechargeable battery types. They are fairly fragile, and can be damaged if discharged below a minimum level. However, most devices will include a charge controller to avoid these issues. There have been issues with exploding batteries, although this is rare. Lithium ion batteries have no memory effect, retain their charge for long periods of time, but are the most expensive. Li-ion batteries have a reduced shelf life, and may lose up to 20% capacity per year.
- Nickel Cadmium - NiCad batteries are cheaper than Li-ion variants, and more expensive than NiMH and lead acid. They are the most susceptible to memory effects due to premature charging, but are more resilient than Li-ion and NiMH batteries to long term damage. NiCad batteries can supply higher currents than NiMH, and retain their charge for longer.
- Nickel Metal Hydride - Many NiMH batteries have a high self discharge rate, meaning they lose energy quickly. Newer versions claim to have resolved this issue. NiMH, like Lithium Ions, can be damaged by discharging below a certain level, and should be used in devices with charge controllers. When charging, one should use a proper smart charger to avoid overcharging, which can cause damage. NiMH batteries have a higher capacity than similar NiCad versions.
- Lead Acid - Lead Acid batteries are the cheapest version of rechargeable per storage capacity. They are also the heaviest with the least energy density.
Battery Form Factors
There are many different shapes and size of batteries, each with their own voltages and common uses.
- 9-Volt - 9-volt batteries are increasingly uncommon batteries due to the increasing efficiency of electronic devices, some devices still do require these.
- AA - AA 1.5 volt batteries are the most common battery, used in flashlights, radios, GPS, and many other devices. Devices that accept AAs will often accept AAAs in a pinch.
- AAA - AAAs are also very common and are essentially identical to AAs except for a slightly smaller size needed by some compact devices.
- C - C 1.5 volt batteries are common, but are generally only used by larger, older style flashlights and larger portable radios.
- CR123 - CR123s are newer 3 volt batteries that were designed to meet the demands of certain high-power devices while being very compact. They are increasingly common in cameras and flashlights.
- D - D batteries, identical to C batteries except for their larger size. Like Cs they are also mostly used in large flashlights and large portable radios.