Being able to count on your power supply or battery to keep your customers’ systems up and running may be one of the most critical factors in selecting these devices. Not only does the device have to fit the application and meet building and life safety codes for power and safety, but the quality of the power has to be excellent.

Designing power specifically for the application is the best way to go. SDM subscribers were asked, via an Internet survey, about how they select batteries and power supplies. Reliability came through as an important factor in the selection process and some 25 percent cited this as a consideration in choosing a power supply or battery. Reliability also may relate to proper application specifications. Martin Souder, owner of T&M Alarm in Rome, Ga., offered this tip to his colleagues considering purchasing a new power supply: “Find the best supply for the specific application. Size and life are important, and don’t ‘undersize’ for the job.”

Bill Hass, customer care technician for ASG/Aronson Security Group Inc., Seattle, goes one step further in providing this advice: “Always add 25 percent more capacity than you think you need,” if possible when purchasing a new power supply. On selecting a new battery, he says, “Make sure the power supply can charge the battery and always check the loads.” He warns of under-sizing the power supply for the application.

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Before You Purchase

Selecting the correct power supply or battery for a project is critical. Alan Forman,

president of Altronix Corp., Brooklyn, N.Y., offers these tips to installing dealers:

• Check the specifications for the tolerance

of the voltage.

• Find out the continuous current amount when invoking magnetic lock

or pan-tilt-zoom or other controls.

• Make sure the power supply can handle surges or has spike protection.

• Calculate the voltage drop for long paired wire runs (Altronix has an on-line calculator for this). The voltage drop is the amount of voltage lost between the originating power supply and the device being powered.

• Investigate the compatibility to interface with other devices seamlessly.

• For power-limited wiring, don’t exceed the current at the prescribed voltage.

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Avoid these Pitfalls

SDM asked dealers and installers: What one pitfall can you warn your colleagues to avoid when purchasing a new power supply?

• Don’t let specs fool you. Verify the unit’s specs match what unit is fused at. (For example, it may be rated as 2A P/S, but fused at 1 or 1.5A.)

• Make sure it is a regulated power supply and it matches the equipment you want to use it with.

• It must be able to monitor the AC and DC

side for trouble.

• Avoid unsupervised supplies that do not

report a low battery when it occurs, before it

causes a false alarm.

• What one pitfall can you warn your colleagues to avoid when purchasing a new battery?

• Don’t buy the cheapest battery on the market.

• Purchase an adequate size for the application.

• Do not overcharge the battery the first time you charge it.