1. Power Supplies And Batteries ARRL Book Section 3.3

2. Why Mobile First Many emergency responses may require you to move around Another reason is that a radio needs power –Most disasters take out electric power –Keeping batteries charged and ready can be tough –But your car keeps a battery charged most of the time (when its working right) For people not using mobile you need to have battery power available for when the commercial power fails.

3. To Recharge or Not to Recharge Some batteries are one time use –Carbon-Zinc batteries are not designed to be recharged (T4C08) Keeping rechargable batteries ready to go can be challenge –Batteries wear and leak their charge (even when they are not used) –You need to inspect your batteries regularly for damage, store them in a cool dry place, and give them a maintenance charge at least every 6 months. (T4C09) The best way to get the most energy out of a battery is to draw the power steadily but as slowly as possible (T4C10) –This is one reason during practices to see how little power you can use to reach other individuals you must communicate with Slow steady pace is also the best way to recharge –If you charge or discharge a battery too fast it can overheat and either explode or give off dangerous gas (T0A11)

4. Most Common Rechargeable Nickel-Cadmium batteries are rechargeable standard –Need several Ni-Cd batteries to run a radio – standard radio runs on 12 volts, A single Ni-Cd battery only puts out 1.2 volts (T4C07) –Some handheld radios run on less than 12 volts to avoid needing 10 batteries, but that also tends to limit output power of the handheld –Ni-Cd batteries have memory effect, if you charge them every time they are ½ discharged soon you can only use half the capacity Discharge a Ni-Cd battery completely and then recharge it.

5. Other Battery Choices Lithium-Ion Batteries offer the longest life (T4C06) –They also offer the highest price and need a special battery charger $$$$$$ Lead-Acid battery (like in your car) is another choice –Battery weighs like its made out of lead (oh it is) – not very tempting for a hand held radio –Can put the battery in your home and charge it but there are risks It contains dangerous acid that could spill or cause injury (or make you need an underware change after seeing your kid or grandkid playing with it) Short circuits can damage wiring or cause a fire (seeing a short circuit across 2 battery terminals is some pretty amazing fire works) Explosive gasses can collect if not properly vented (gas is hydrogen – Remember the Hindenburg?) (T0A10) Not all Lead-Acid Batteries are created equal, a car battery is designed for high output and then recharge (ie its designed to start a car engine) –Radios use little power but they keep using it and discharge the battery, a car battery won’t last long on that kind of cycle –Consider a Marine type or Deep Cycle Battery – they are designed for small loads and being discharged before recharging

6. Radios Can Be Run Using Household Power Lets you practice using regular power while keeping your batteries outside of living space –Radios do use 12 volt DC but lot of things have those big plugs with transformers inside –For a Radio you want to use a regulated power supply to protect against voltage fluctuations. (T5A05) Picking power supplies –Obviously want right voltage (usually 12 volt DC) –Rated by Watts or Amps If its rated it Watts almost certainly to small Look at amperage your radio can draw on full power transmit and pick a supply with that amperage –Be careful Radio Shack 15 amp is cutting it kind of close –My supply is a 35 amp Pyramid – but I run several radios at once.