Runtime Recommendations

January 20, 2022 by CyberPower

You rely on your UPS system for backup if your power goes out, right? But does your UPS have your back? That is, will it provide a bridge of power long enough for what you need? At the very least you will want to save your data and perform a safe shutdown. Your UPS backup battery will only provide power for a set amount of time, known as runtime. In this article, we will provide a step-by-step approach to determining your runtime requirements so you can find the right UPS system for your needs.

The first thing you need to consider is how much backup power you need. Most power outages only last for five minutes but some can be longer. To make sure a UPS is providing enough backup power for your most critical equipment, you need to understand runtime requirements.

To calculate the runtime you need, you have to find out how much power, or load, is required by your connected devices and the capacity of the UPS system battery.

How to determine your runtime requirements
Step 1: Defining the basics
Let’s start with the basics by defining voltage, amperage, and wattage:

  • Voltage = Most equipment operates on 120V or 208V AC in the United States.
  • Amperage = This is the power that your device draws, which may be as small as 1 amp or less and is capped at the maximum amperage of the circuitry in your home or facility. Typically, a 15A outlet is used in most homes and businesses. If your device requires more than 15A, you’ll need to ensure you have the correct outlet. Your device’s amperage may be found…
    • printed directly on the device, often on the back or near an outlet or port
    • printed on a specifications label on the back of your device
    • printed in your device’s user manual
  • Wattage = The amount of power your device uses.

Step 2: Calculate total wattage of protected equipment
There are three ways to find your wattage:

  • Specified in the device’s user manual
  • Located on the safety label of the device or the device’s power supply (specs are usually on the transformer)
  • If wattage is not listed on the above items, it can be calculated from the voltage and amperage information:

Voltage x Amperage = Wattage

Note: When calculating the wattage load, your load level should not exceed 80% of the capacity of the UPS system. To establish the overhead capacity, multiply the total load by 125% to calculate the minimum capacity needed for the UPS system.

Example wattage Calculation:

Note: In this scenario, the Total Load was multiplied by 1.25 to determine the UPS size with overhead.

Step 3: Calculate required runtime
To calculate the runtime, let’s establish the typical load. To do this,
multiply the minimum wattage capacity required for your devices by 65%.

Using the same example from above, the minimum UPS capacity is 188W. Multiple this number by 65% to find the typical wattage:

188 W x 65% = 122 W

Once you determine your typical wattage, use this helpful calculator to determine which UPS is appropriate for your connected equipment

Need extra runtime?
Every UPS system is different. Double-check how much runtime your UPS battery provides with a full load. If you need more runtime, you may need to get a UPS with more capacity or add battery modules. Available for select UPS systems, one or multiple Extended Battery Modules (EBMs) can add runtime. Based on your load requirement, you can add EBMs to your system to reach your desired runtime. Other alternatives include connecting your UPS system to generators to gain a longer period of backup power.

Power surges and outages are an unfortunate reality, but you can stay powered and protected with a UPS system with the appropriate level of backup power and runtime for your needs. And now, you have the tools to calculate the runtime you need to save your data and safely shutdown your devices.

For more information and to find your next UPS system,