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FAST FACTS How does a Battery-Operated Power system work? The system has 4 major components which are controlled by a microprocessor:
The microprocessor monitors incoming power quality, battery voltage and temperature, demand loads and such values, and controls these components. How long will it run? Electric energy is measured in watt-hours (or Kilowatt Hours - 1000 watt-hours), as you know from your electric bills. One hundred watt-hours is 100 watts for one hour, or fifty watts for two hours. Watts is the product of amperes and volts. Utility voltage is always about 120 volts as long as all is well, so simple math tells us that amps and watts are directly proportional: divide watts by 120 volts and you have amperes. For the purposes of this discussion we will call them “Utility Amps.” Battery energy storage is measured in Ampere-Hours (amp-hrs.). It must be realized, however, that a battery’s capacity depends on its discharge rate. A quickly-discharged battery will provide you with considerably less energy than a slowly-discharged one. Battery manufacturers rate their batteries at a 10- or 20-hour discharge rate and then provide a chart to help an engineer figure out how to de-rate it according to the expected time frame. Another point of confusion is that a battery’s voltage might be 12 Volts DC and we want our answer in 120 Volts AC. First, there is a conversion-efficiency loss in converting DC to AC, and secondly an apparent loss as we convert from 12 volts to 120 volts. Since Watts is the product of Volts x Amperes, as we change from speaking of “Battery-Amps” at 12 Volts to “Utility-Amps” at 120 Volts, we must divide our “Battery-Amps” by 10 to get “Utility-Amps.” The bottom line of all this can be summarized by this rule-of-thumb: A 100 Amp-Hour battery, rapidly discharged over a one hour period, stores about 0.67 Kilowatt-Hours of converted power. Here are formulas:
Can I install it myself? Absolutely! The Silent Sentry® is available in two versions:
The unit itself is shipped in two parts which attach to each other with screws. Wall mounting flanges then attach to the assembled unit. These are designed to lag-bolt to wall studs 16” on center (14” between). The installer can choose to surface-mount to the wall or cut an opening in the wall to allow the unit to be partially inserted into the wall for a low-profile installation. After the system is firmly attached to the wall, two or three batteries are installed, the cover replaced and the system is ready to use. How does it ship? The Silent Sentry® can be shipped via United Parcel or other package delivery service. This keeps shipping costs as low as possible. The base model ships in five cartons Are the batteries safe? There are many ways to store energy and each has inherent problems and safety concerns. There is no known direct means of storing electric energy for more than a few minutes. Liquid and gaseous fuels are flammable or even explosive, emit poisonous gases and waste heat when employed, and are best reserved for outdoor use. Mechanical methods such as compressing air, pumping water to a height or spinning a heavy flywheel in a vacuum are generally impractical or very costly to build. Lead-Acid battery technology is a mature science and is considered very safe and reliable. New technology using sealed containers, fiberglass matting to hold the acid electrolyte in a sponge-type medium and catalytic anti-out gassing technology have improved this technology to allow indoor use and safe transport. Due respect should always be given to a large battery bank with regard to avoiding accidental short-circuiting by accident prevention. Covers must always be kept in place to protect cabling and terminals. Care in the use of tools around electrical connections is always an imperative. How often should the batteries be replaced? The recommended replacement period is four years. How does battery inverter–charger technology compare with a fuel powered generator? Inverter-chargers excel when compared to fuel-powered generation in that they are instantly on upon utility power failure. There is virtually no start-up time – preventing computer data loss or the need to restart microprocessor-controlled devices. The power produced is very pure compared to the “dirty” power produced by typical, small generating plants, which can be very damaging to electronic equipment. Frequent use of local power generation systems – for example during repeated system testing regimens – can also degrade power-protection devices over time-gradually rendering them useless. Inverter systems produce minimal audible noise, very little waste heat and no odors. They are much simpler to install and can be located indoors. Since inverter systems are electronic they have no moving parts to wear out or lubricate. If power requirements are not excessive they are generally less expensive. If it is necessary to power large heating systems, air conditioning systems, elevators, or other large equipment for extensive or indefinite time periods then a fuel-powered system is indicated, although a battery-powered inverter system may still be necessary as a “bridge” to prevent power loss between the time the primary power supply failure began and the secondary power supply starts up and stabilizes. Typical Appliance AMP Draws All appliances with plugs with a standard configuration are 120-volt appliances, requiring less than 15 amperes (amps). Plugs with different pin configurations will probably have significant power requirements; volts and amps are usually embossed on the plug. In order to evaluate how large a battery bank is required, a compilation of the amps, watts, or volt amps (VA) from each appliance’s electrical rating plate will be most helpful. Consider, also, that some appliances, like sump pumps or furnaces, cycle on and off. A ratio of on-time versus off-time will also be useful data. A 75 lb. sealed lead-acid battery can support a 5 ¾ amp load for 1 hour. That is a physical fact. Do not be deceived by misleading claims common in advertisements! |
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