Lead Acid Battery Emergency Power
Automotive Starting Batteries technically termed SLI, for starting, lighting, and ignition batteries are commonly used to start and run engines. Engine starters need a very large starting current for a very short time. Starting batteries have a many thin plates for maximum surface area. The plates are composed of a Lead "sponge,” because of its porous appearance. This gives a very large surface area, but if deep cycled, this sponge will quickly be consumed and fall to the bottom of the cells. Automotive batteries will typically fail after 30-150 deep cycles even if promptly recharged. Of course, they may last for thousands of cycles in motor normal starting use (2-5% discharge).
The Automotive battery may be your battery of choice in an emergency simply because it is all that may be available to supply the nominal 12 volts DC needed to run a radio. A proven advantage is the ability to go to nearly any automobile or light truck and obtain a battery that should give several hours, or even a day of emergency service in operating a solid state HF transceiver and moderate power VHF-UHF rig mainly in the listen mode. For charging, it can be returned to the vehicle and perhaps another one barrowed.
Marine Batteries are usually actually a "hybrid,” and fall between the starting and deep-cycle batteries, while a few are true deep cycle. In the hybrid, the plates may be composed of Lead sponge, but it is coarser and heavier than that used in starting batteries. It is often hard to tell what you are getting in a "marine" battery, but most are a hybrid. "Hybrid" types should not be discharged more than 50%. Starting batteries are usually rated at "CCA,” or cold cranking amps, or "MCA,” Marine cranking amps - the same as "CA.” Any battery with the capacity shown in CA or MCA may not be a true deep-cycle battery. The terms marine and deep cycle overused. CA and MCA ratings are at 32 degrees F, while CCA is at zero degree F. unless you have access to the battery manufacturer’s engineering department exact information on construction and application is difficult to know for sure.
Deep cycle Batteries can be discharged as much as 80% of
rated capacity many times. They have
much thicker plates than automotive batteries.
The major difference between good deep cycle batteries and others is
that the plates are solid lead plates - not sponge. Unfortunately, it is often impossible to tell what you are really
buying in some of the discount stores or places that specialize in automotive
batteries. The popular golf cart
battery is generally a "semi" deep cycle - better than any starting
battery, better than most marine, but not as good as a true deep cycle solid
Lead plate. However, because the golf
cart batteries are so common, they are usually quite economical for standby
Gel Cells or gelled batteries, contain acid that has been "gelled" by the addition of Silica Gel, turning the acid into a solid mass that looks like gooey Jell-O. The advantage of these batteries is that it is impossible to spill acid even if they are broken.
Some disadvantages are: They must be charged at a slow rate, typically no more one twentieth ampere hour capacity to prevent excess gas from damaging the cells. This means they must not be fast charged with a conventional automotive charger or they may be permanently damaged. If overcharged, voids may form in the gel, which never heal, causing a loss in battery capacity. Avoid keeping them in hot locations because water loss can be enough over several years to cause failure.
Lead-Calcium Flooded Cell Standby Batteries have the longest service life of the lead acid battery types. They can provide essential services such as telephone and microwave relay sites with substantial current in an emergency. A disadvantage is high initial cost, large size, and weight. Life expectancy is 20 or more years if not discharged to more than 15% of total capacity.
These are shallow-cycle batteries that rarely experienced more than a 15% cycle in telephone service. If you are careful never to discharge them deeply, these batteries can give years of excellent service.
While phone, company batteries can be found at low cost, or even free for the hauling, their weight and size make them difficult to use. Because cycle capacity is limited to 15% or 20%, you have to buy, move, and install five or six times more battery mass than is required for true deep-cycle batteries.
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