Battery Backups and Uninterruptible Power Supplies (UPS)
Battery backups and Uninterruptible Power Supplies (UPS) are essential systems designed to provide power in the event of main electricity supply failures.
While both serve as lifelines during power interruptions, a UPS offers near-instantaneous protection against blackouts, ensuring that critical devices remain operational.
In contrast, battery backups, a broader category, store energy to be used during outages, although they might not always offer the same instantaneous response as a UPS.
Both systems are crucial in safeguarding sensitive electronics and ensuring continuous operations in various sectors, from healthcare and data centers to home offices.
Battery Backup vs. Uninterruptible Power Supply
There's a difference between a battery backup and an uninterruptible power supply (UPS), although the terms are sometimes used interchangeably by people outside the industry. Here's a breakdown of the two:
- At its core, a battery backup is a system that provides power to a device or system for a limited period of time when the primary power source is lost. It might not switch to the backup power source instantly, which means there could be a brief interruption.
- It doesn't necessarily offer protection against power surges or other power quality issues; it just provides power when the main power is off.
- Battery backups are simpler systems and might be used in contexts where a short power interruption is tolerable.
Uninterruptible Power Supply (UPS)
- A UPS is a type of battery backup designed to provide power instantaneously (or almost instantaneously) when the primary power source is lost. This ensures that there is no interruption to the connected devices.
- Besides providing power during outages, many UPS systems also offer protection against power surges, voltage drops (sags), and other power quality issues.
- A UPS is often used with critical equipment like servers, network equipment, and medical devices, where even a brief power interruption could have serious consequences.
- UPS systems can also be classified based on their architecture: offline (standby), line-interactive, and online (double-conversion). Each type offers varying degrees of protection and response times.
As one can see, while all UPS systems are battery backups, not all battery backups qualify as UPS systems. The key difference often lies in the speed of the response and the additional features like surge protection and power quality management.
UPS Response Times
When considering a good UPS (Uninterruptible Power Supply) response time, it's essential to understand that the primary purpose of a UPS is to detect a power outage and switch to its internal battery source quickly enough to prevent the connected equipment from shutting down.
The switchover time for most modern UPS units is typically very fast. Here's a guideline:
- Offline/Standby UPS: This type of UPS remains in standby mode unless a power failure occurs. When it does, the UPS switches to battery mode. The transfer time for offline UPS systems can range from 2 to 10 milliseconds. While this might seem fast, even short interruptions can be problematic for sensitive equipment.
- Line-interactive UPS: These are similar to the offline/standby design but have added voltage regulation features. The typical transfer time for this kind of UPS is similar to an offline UPS, generally between 2 to 10 milliseconds.
- Online/Double-conversion UPS: This is constantly converting incoming AC power to DC (to charge its battery) and then back to AC for the connected equipment. Because of this continuous conversion process, there is technically no transfer time in the event of an outage; the transition is instantaneous (0 milliseconds). This type of UPS is the best choice for very sensitive equipment.
For most consumer-grade equipment and general IT infrastructure, a transfer time of a few milliseconds (like what you get from an offline or line-interactive UPS) is typically sufficient.
However, for mission-critical infrastructure, medical equipment, or other highly sensitive setups, an online UPS with a 0-millisecond transfer time would be the preferable choice.
UPS vs. Solar Generator with Pass-Through Charging
A UPS (Uninterruptible Power Supply) and a solar generator with pass-through charging serve different primary purposes, but both can provide backup power in the event of a power outage.
Here are some of the most important differences between them:
- UPS: A UPS's primary function is to provide instant or near-instantaneous power backup in the event of a power outage, ensuring no interruption to the devices connected to it. They are often used with critical equipment like servers, computers, medical devices, etc.
- Solar Generator with Pass-Through Charging: This device's main goal is to provide a portable power source, typically using stored solar energy. The pass-through charging feature allows the generator to charge its internal battery while simultaneously powering connected devices. Solar generators are often used for outdoor activities, off-grid living, or emergency backup in various scenarios.
- UPS: Typically charged from the mains electrical grid.
- Solar Generator: Primarily charged using solar panels, although many models can also be charged from the mains electrical grid or a car.
- UPS: Typically AGM or Gel-cell deep-cycle batteries - heavy but affordable and suitable for permanent installations and applications where batteries don't cycle often.
- Solar Generator: Commonly Lithium Iron Phosphate (LiFePO4) or rarely Lithium Polymer batteries - lightweight and suitable for portable devices that cycle a lot, especially LiFePO4 batteries.
Duration of Power
- UPS: Usually provides power for a short duration, long enough to safely shut down connected devices or switch to another power source. Some more advanced units even feature RS232, RS485, USB, RJ-45 ports, or even Bluetooth/WiFI modules to send diagnostic data, warnings, and alarms to protected equipment and to initiate their automatic shutdown when their internal batteries are discharged below a previously set level.
- Solar Generator: Can often provide power for a longer duration, depending on the battery capacity and energy consumption of connected devices. It can be continually recharged during daylight hours if paired with adequate solar panels.
However, one also must note that many larger and more advanced UPS models support the use of external batteries for longer operation while on batteries.
Power Quality and Features
- UPS: Offers protection against power surges, voltage sags, and other power quality issues. Some advanced UPS units provide pure sine wave output, which is crucial for sensitive electronic devices.
- Solar Generator: While some solar generators provide pure sine wave output, they might not offer the same level of protection against power quality issues as a UPS.
Portability and Use Cases
- UPS: Generally stationary and used indoors, often in office settings or data centers.
- Solar Generator: Designed for portability and outdoor use, making them great for camping, RVs, outdoor events, or off-grid applications.
- UPS: Mainly relies on grid power, which might come from renewable or non-renewable sources, depending on the region.
- Solar Generator: Emphasizes green, renewable energy by harnessing sunlight and reducing carbon footprint when used as the primary charging method.
For scenarios where maintaining continuous power is critical (e.g., sensitive electronics, medical equipment), a UPS is more appropriate due to its rapid response time.
On the other hand, while solar generators offer valuable benefits for off-grid power and renewable energy applications, they might not provide the rapid response needed for applications sensitive to even brief interruptions.
However, solar generators that are designed to operate as both solar generators and as UPS feature very low response time, and internally, they are very similar to online (double-conversion) UPS units - they are charging the battery using car, grid, or solar energy, and at the same time, they are providing power to external loads using the very same battery.
How to Size a Uninterruptible Power Supply (UPS) and Battery Backup
Sizing an Uninterruptible Power Supply (UPS) and battery backup involves several steps to ensure that the selected system will adequately support the connected devices during power outages and provide enough runtime.
List All Devices to be Powered
Before sizing your UPS, you should know exactly which devices you intend to connect. This could include computers, servers, network equipment, or other essential devices.
Determine the Power Requirements
- Wattage: Check the power rating of each device, typically given in watts (W). This information can usually be found on the device itself, its power supply, or in the product manual.
- VA (Volt-Amperes): Some UPS systems are also rated in VA, which is related to watts but might be slightly different for certain equipment. If only the VA rating is provided, it can be used to estimate watts: Watts=VA×PowerFactorWatts=VA×PowerFactor. Power factor values range from 0 to 1, with many real-world devices having a power factor between 0.6 to 0.9.
- Sum up the total wattage (and VA if necessary) of all devices you plan to connect to the UPS.
Estimate Desired Runtime
- Decide how long you want the devices to run during a power outage. This could range from just a few minutes (enough time to safely save work and shut down) to several hours.
- Note that increasing runtime typically requires a larger battery, which can significantly affect the size and cost of the UPS.
Factor in Future Expansion
- It's wise to account for potential growth or the addition of more devices in the future. A common practice is to add a 20-25% buffer to your total power requirement to account for this.
Choose a UPS/Battery Backup
- With the calculated total wattage (and VA) and desired runtime, you can now select a UPS. Make sure its output capacity meets or exceeds your calculated needs.
- UPS systems usually come with an estimated runtime for various loads. Ensure the model you're considering can achieve your desired runtime for your total load.
Battery Backup Expansion
Some UPS units allow for the addition of external battery packs. If you require longer runtimes than a standard UPS model offers, look for units compatible with external battery expansion.
Consider Additional Features
Beyond pure power requirements, think about additional features you may want that come in handy immediately or one day.
- Pure Sine Wave Output: Essential for sensitive electronics.
- Automatic Voltage Regulation (AVR): Helps stabilize voltage sags or spikes.
- Communication Ports: For integration with systems or remote monitoring.
- Surge Protection: For added safety against power surges.
Regular Maintenance and Testing
- Once your UPS is in place, regularly test and maintain it to ensure its reliability. Batteries age and degrade over time, so they'll need to be replaced every few years, depending on usage.
Note: FYI, the author of this article uses an APC UPS to power the laptop with two external 27" monitors (additional ports provided via USB-C). UPS is set to turn off the laptop in 10 minutes after mains power is lost, while UPS's beeper is turned off since it can be rather annoying ;)
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