Part II: The Foundation
In both field work and emergency communication, the situation drives the equipment requirements. Part I discussed the general power requirements for emergency communication and field work. This article will talk about batteries for hand-held radios, especially alkaline batteries. Part III will talk about batteries for mobile and desktop radios.
Batteries: The Foundation of Field Power
In Part I, the following requirements were discussed:
Batteries are the best available technology that fill these requirements. They form the foundation around which we can build our plans.
We can summarize the way that batteries match the above criteria thus:
- Their ability to provide power is known and predictable, so they can form a reliable source of electrical power.
- They free the radio station (and thus the radio operator) from the grid.
- For situations that require smalls size, batteries can be made quite small (in exchange for less power).
- For situations that require low weight, batteries can be made quite light (in exchange for less power).
Modern hand-held radios, commonly known as “handy talkies” (HTs) ordinarily run off of rechargeable batteries, with an option to use standard alkaline batteries.
For emergency work, local ARES (Amateur Radio Emergency Service) members have consistently stressed to me that it’s important to be able to use alkaline batteries. One veteran phrased it as “in an extended emergency, AA and D batteries will be the staple of radio operators”.
Here are some of the reasons why alkaline batteries hold such an important role in emergency communications.
- Rechargeable batteries may not provide power when needed. They slowly discharge in storage and require periodic recharges. I have repeatedly experienced dead rechargeables when I needed them, not only with radios but with cameras and other electronics.
- Alkalines can be stored for long periods of time.
- Alkalines are readily available in most stores, and need no preparatory charging before they can be used.
- Recharging batteries can take hours. Changing alkalines takes seconds.
- Should your batteries die, someone else on the scene will likely have some alkalines that you can use.
This does not mean that you should not use rechargeable batteries. They’re convenient and can be your “plan A”, or convenience plan. However, ensure you build your plans on a foundation of alkalines.
The catch for many HT models is that they will not run at full power with alkalines (e.g. ½ watt instead of 5 watts). For those who have these kinds of radios, you can make an external battery pack to fool the radio and run at full power. (Article to follow.)
While you should not build your HT power plans around rechargeable batteries, they’re convenient. When coupled with a recharger placed in a strategic position, you rarely need to change batteries.
The rechargeable batteries types that you’ll encounter on HTs are:
- Nickle-Cadmium (Nicad)
- Nickle-Metal Hydride (NiMH)
- Lithium Ion
Each type of battery has its strengths and weaknesses. Here is a summary, with notes to follow.
Wide temperature range
Long charge time
|Nickle Metal Hydride||High energy capacity||Memory effect
Poor low temperature performance
|Lithium Ion||Light weight
Good energy capacity
Poor high draw performance
Sensitive to high tempertures
Nicad batteries are solid performers and have the lowest self-discharge rate, but when they decide to finally die, they can do quickly without warning. They also require special disposal due to the dangerous chemicals inside.
NiMH batteries store a lot of energy but should not be used in colder weather.
The “memory effect” is a problem with nickel-based batteries (nicad and NiMH). If they are repeatedly recharged when not fully empty, they lose their ability to fully discharge. They “remember” the partial discharged state as the bottom of the tank, as it were. You must periodically drain them completely so they can “remember” where “fully empty” is.
Lithium ion batteries are fabulous for their light weight and ability to take partial recharges. However, they should not be kept in hot vehicles in the sun during summers. Heat will kill them. I have not personally verified the reported “venting with flame” claims that are supposed to happen at high temperatures.
Part III will talk about batteries for mobile and desktop radios.