- 1). Search for the product specifications of your computer, and any other related hardware items you will want connected to the backup battery, for the amount of watts required to power all of the items. Write these amounts on a piece of paper. Add the amounts together; this is the minimum amount of watts you need your backup battery to produce.
- 2). Decide how long you will need your backup battery to power your computer. This is called the "run-time." A short run-time will allow you to save what you are working on and shut down your computer system. A longer run-time will allow you to keep working. Backup batteries that provide a longer run-time are more expensive than ones that only provide you with enough time to save and shut down. Write down on your paper the amount of run-time that you need to have provided by your backup battery.
- 3). Know your voltage for the region you live in; the voltage is the standard current available in homes and offices. If you live in North America you will need a backup battery that works with 60Hz. Your backup battery is charged through you home or office building's voltage. Your computer plugs into the battery and the battery plugs into the wall. The battery is only used when the current from the building's electrical system is interrupted, otherwise it is in a state of trickle charging while it allows the current to pass directly to your computer. Your backup battery must be compatible with your building current to maintain its charge and to allow the current to pass through to your computer. Note the voltage that your backup battery needs to work with on your list.
- 4). Choose the features that you need. Each additional feature on a UPS system can add significantly to your cost. You can choose a backup battery system that will automatically instruct your connected hardware to power down. Another option available is where your backup battery can detect when power is restored and switch your hardware back on. Write down a list of features that you want with your system.
- 5). Decide if you need an online, offline or line interactive system. An offline system is the cheapest, and it detects power interruption and switches the power for your computer to the battery, but must be manually switched back. An online system is the most expensive and is used most for situations that involve monitoring or powering life support equipment. It transforms all power to a monitored and stable output regardless of whether the power is originating from an outside source or the battery. A line-interactive system detects fluctuations in the power supply, or surges, and switches between battery and live power to provide uninterrupted power automatically. Write down which system best suits your needs.
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