|
A guide to self reliant living |
||||
|
6. Kerosene heaters and cookers
12.
Electrical; generators
Miles Stair's SURVIVAL
Miles Stair's
SURVIVAL |
BATTERY PRIMER by New England Gardener The older, common flashlight batteries were carbon zinc, and are still excellent for providing small amounts of power for portable radios and ordinary flashlights. They used to have much trouble with these batteries leaking acid that ruined the contact points and what ever you had installed them in, a year or so after they were made. Improvements have been made, but I still store these separately, and use them up or throw them away after a year. I buy them after the Christmas rush, when their use in toys makes it likely they will be fresh, and replace them all the next year. These are usually called "heavy duty" today, and cost noticeably less than the ones labeled Alkaline. Alkaline batteries are better for things that use more power like bright search lights, or anything with a motor in it. They won't really last much longer with a small load though. The biggest advantages are a much longer shelf life of 5 years, and that they are much less likely to leak and damage your equipment. The common battery sizes are D cells, the smaller C cell has about half the capacity, and the AA cells have 1/4 of the capacity of the C cells. That s the way they were designed when all of these were carbon zinc, but it still is a rule of thumb when comparing non-rechargeable batteries of the same type. Rechargeable batteries in these sizes have been available in nickel cadmium [Nicad] and the newer nickel metal hydride [NiMH]. The situation is similar, the earlier Nicads are better for light loads, hold their charge for months, and can be recharged about 1,000 times, so they are best for small radios and flashlights, especially the new LED lights. Uncharged, they have a pretty much unlimited shelf life, and in regular use 5 years or more of service is normal. I recharge these about every six months, often they haven't gone dead yet, but digital radios really don't like the low voltages they have when they go dead in use. I am having trouble finding these now, as most people have gone to the NiMH, which can store several times more power, so they are popular for digital cameras and walkie-talkies. The draw back is they discharge in storage, so you will need to charge them every month, or BEFORE you use them, not to handy for an emergency. The charger must be suitable for the type battery you have, and needs some circuitry to prevent these two kinds from developing a "memory" and not taking a full recharge, or you can run them dead on a flashlight, and then charge them with a solar panel or charger. C. Crane Radio and Universal Radio both have chargers that condition the batteries and operate from either 12vdc auto or RV battery or 125vac wall current. I have both 6 and 12 volt solar panels from C. Crane. The 6 volt one will run several of the Sangean radios they sell directly, or recharge a battery pack of 4 cells, or a 6 volt rechargeable battery. The 12 volt ones put out ten watts, and are suitable for recharging lead acid batteries of larger sizes. These come in several types. One thing about all types of individual cell round batteries, clean the ends of the batteries and where they contact the holder with alcohol and dry with a rough cloth. Any corrosion will waste energy. Lithium batteries are expensive but offer some important survival advantages. They can hold far more power for their size and weight, they continue to work well at low temperatures, and have a long shelf life of ten years. They also stay near full voltage over their discharge life. These things have made them popular for computer clock, radio memory, and tactical operations flashlights and two way radios where recharging will not be done. So they are great for the flashlight and radio in your bug out kit, vehicle or RV. They are available in the small 9volt size used in smoke detectors, and as a back up battery for alarm clocks and some weather radios. There is a small LED unit that snaps onto the terminals, and has a high and low light setting, and works with this size battery. There is a Lithium-Ion rechargeable type used in Laptop computers too. There are also some batteries of unusual lengths made for tactical flash lights, because each cell has a higher voltage than other batteries, or you can change the bulb to match these batteries. Battery cell voltages are different with some types. The carbon zinc and alkaline are 1.5 volts, the Ni-cad and Ni-MH 1.25 volts. Lead acid are 2 volts and Lithium are 3 volts. Technically a battery is a group of two or more cells used together. If we want 6 volts, we can connect identical cells whose voltage adds up to 6, one after the other, this is called in series. If we need more power, we add groups like this of the correct voltage next to each other, and this is called in parallel. Once connected, this whole group becomes one battery, and needs to be charged or replaced as a unit.
Measuring electricity Circuits operate at a voltage, and use an amount of current measured in amps to operate. To determine wattage or power, we multiply volts times amps. Often we deal with numbers much smaller than one, so we measure in thousands of, or milliamps, or milliwatts. or 0.5 amp=500milliamp and 0.5 watt=500milliwatt. Batteries are rated in Amp hours or milliamp hours, which is how much currant they can provide for one hour. A common 6 volt square rechargeable lantern battery, of lead acid construction, has 3 cells inside and can provide 5 amphours of use. This would be 30 watts for one hour, or a longer time with less amps, such as 30 hours at one watt. The early AA size NiCads were rated for 600 milliamphour [mAH], but I see AA NiMH cells rated for 2300 mAH which is 2.3 amphour [AH]. Your car battery is made to supply quite a bit of power to start your engine, and then be recharged right away. You want a deep cycle battery. They are available for RV's and trolling motors for fishermen in sizes similar to your auto battery, in many larger sizes for large solar arrays. These batteries can store enough power to weld metal and start fires, so make sure you know how to connect them and use fuses or the Square D brand circuit breakers rated for AC or DC. There are also smaller sizes that are portable. Cabela's carries the rechargeable lead acid square 6 volt lantern battery and 6 and 12 volt rectangular ones, and Universal Radio has larger ones too. These are sealed so they won't leak like a car battery, and are good for several hundred discharge cycles, but last better if recharged after use. I like to have radios and flashlights that use the same size batteries, and two or four AA cells is the most popular size for that now. Solar panels are rated in watts they can provide in full light, pointed at the sun. You multiply the hours of bright enough sun light times the wattage to get a total power for that day. Some designs are better than others at working on cloudy days, and they will not work properly if any part of the array is shaded by something. They are really quite expensive for the power they can produce, but once you have them set up, the power is free. They are fragile. I keep mine safely stored away, but they will keep small batteries charged to run LED lights and shortwave radios at night, or run radios during the day. As a rule of thumb, you want a large enough charging current to recharge the battery in ten hours or so, solar or from some other source. An alternative to all the recharging equipment is to buy fence charger or lantern batteries, of the voltage of your radio, LED or flashlight bulb. Lantern batteries are available in the square 6 volt and the rectangular 12 volt, and the much larger fence charger batteries are too. In some areas you may find Alkaline 9 volt fence charger batteries used overseas. They have a tab you remove when you put them in service, and a 5 year shelf like before that. It's important to get these batteries fresh from a farm supplier that sells them regularly. They were designed to have longer shelf life than individual cells and will run small loads very well for months. Another good item to have is a radio/flashlight with a built in crank to recharge it. They are available from Grundig/Eton, BayGen and Coleman as well as others. Some even have solar cells built in.-New England Gardener
|
|
||
