Battery Backup or Surge Protector

Computing equipment likes a nice, steady flow of current. Sudden overvoltages can damage or destroy a computer. These can come from a lightning strike, a fallen tree shorting the power lines, a squirrel in a transformer, or just a poor-quality power grid.

Undervoltages are bad too. They most often come from brownouts when demand on the power grid is high. When the outlet isn’t delivering enough voltage, power supplies have to draw more current to compensate, stressing them and possibly causing long-term damage.

Surge protectors and battery backup units will help to protect against these conditions. Which should you use?

Surge protectors

The low-priced option is the surge protector, available in any hardware or department store. They keep overvoltages from getting through and can save a device from serious damage. They’re commonly available as power strips or as outlet boxes that plug into the wall outlet.

A lot of surge protectors include connectors to protect telephone lines. Phone lines don’t carry the high voltages of power lines, but they can also get shorted out or hit by lightning.

A surge protector has a limited lifespan. Its protection comes from metal oxide varistors, or MOVs. Each time they stop an overvoltage, they take some damage. Eventually, they stop working. Depending on the model, this can mean that they stop delivering current, or that they deliver current but no longer protect it.

Surge protectors are fine for appliances, home entertainment, and many other uses. They’re limited, though, especially when used with computer equipment:

  • They provide no protection against undervoltage or power failure.
  • Their two failure modes are turning into a brick and turning into a plain power strip. The first one is very annoying and sometimes harmful, since it’s like pulling the plug on your computer. The second one leaves you thinking you’re protected when you’re not. Some protectors have a light that tells you when they aren’t protecting, but that’s not a very obvious indicator.
  • A really big surge, such as a direct lightning strike, will overwhelm them. Even if a protector dies trying to save your equipment, the voltage will likely arc across it.

Battery backup

A battery backup or uninterruptible power supply (UPS) provides a higher level of protection. It stores electrical power in a battery during normal operation so it can continue to provide power if the wall outlet stops working.

They come in two varieties: Standby and continuous. A standby power supply normally delivers line current directly. It usually, but not always, incorporates surge suppression. When power fails, it switches to delivering power from the battery, at the same voltage and frequency as line AC (120 volts at 60 hertz in the US). There will be a momentary drop in current when it switches over.

A continuous UPS always delivers power through its battery. This provides a higher level of protection, especially against brownouts. It may provide cleaner current than incoming electrical power, including a more consistent AC frequency. On the downside, it consumes more power than a standby power supply, since it’s always charging its battery.

Battery backup units have a limited life, but they fail more gracefully than surge protectors. The battery will grow weaker over time. With most units, it can be replaced without buying a whole new unit.

Direct lightning strikes will overwhelm a battery backup unit just as much as a surge protector. Really, very little will help in that case, except for the very expensive equipment which radio towers use.

Which to use?

A consumer-grade surge protector is good enough for many situations. Computer equipment, though, should use battery backup, preferably a continuous rather than standby unit. A good continuous power supply will guard against overvoltages, undervoltages, and dirty current, preventing system shutdowns and extending the life of the equipment.

BWS Technologies provides the support that will keep all your computer operations running smoothly. Please contact us for more information.

  • 11/03/2016
  • IT