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Top 6 Techniques For Remote Monitoring UPS Batteries


December 23, 2021


An Uninterruptible Power Supply (UPS) is a backup power source that activates when the main source of power fails, but what happens when its batteries run out of power? Having a generator on-site is always a good idea in the event of extended outages. In addition, having a system to remotely monitor your critical equipment can be the difference between a quick-fix and a very expensive repair.

Although complex, a UPS has a very simple overall design. Every UPS has power inputs (for the intake of commercial power during normal operation), power outputs (to connect protected equipment), and backup batteries (to prevent interruption of power to protected gear when commercial power is lost). It also has a control system that quickly switches to backup battery power when the main source of electricity goes down.

The word "uninterruptible" means that the power supply will act quickly enough to prevent the gear from ever losing power when the main power source goes dark. This usually means that a UPS system must be capable of activating backup power within 25ms of a power loss.

A UPS is, by nature, redundant. This means that it provides an important protective barrier against data loss, outages, and expensive hardware damage (by smoothing out voltage anomalies).

In consumer applications, a UPS may only have enough battery reserve to last for a few minutes. The intent of such a short backup power supply is only to allow the safe shutdown of connected computer gear.

In a telecom or data center environment, however, the batteries of a UPS may last for several hours or more. If commercial power failures are most likely expected to be rare and brief, a UPS may be the only backup power source at a remote site. However, at least one diesel or propane generator can also be present to provide backup power.

Whatever your particular scenario is, if you depend on a UPS system to protect critical gear at your remote sites, then you want to remotely keep an eye on it. Let's explore some more facts about the UPS, and the most important techniques and key factors that you should keep in mind to achieve a successful UPS monitoring system.

Tracking of Battery Temperatures and analog Levels
You might find some very complicated ways to monitor your batteries, but the best - and easiest way - to get started is to track voltage and temperature.

Avoid Failing to Properly Monitor Your UPS System

As I said previously, an uninterruptible power supply is vital protection against loss of data and costly hardware damage.

Unfortunately, though, many network managers fail to properly monitor their UPS systems. The main cause for this is that most modern UPS systems for use in industrial applications include a built-in web interface for ups critical tracking. Although this obviously allows "monitoring," one critical failure prevents it from being "proper monitoring."

Using an uninterruptible power supply's own interface for performance and up-time defeats the purpose of such monitoring. What happens if the UPS fails? Well, so too will the monitoring interface that you have relied on.

Instead, the industry's best practice is to deploy UPS power management software. These can come in small monitoring devices (1 RU or less) that are available to collect important status information from virtually any UPS backup system.

These monitoring devices are called "RTUs" - short for Remote Terminal Units or Remote Telemetry Units - and they'll send alerts back to critical personnel via LAN, phone voice message, serial connection, T1, fiber, or any other available transport.

Take a look at the DPS RTU devices here.

This way, companies will have remote access to their UPS systems and can track and log the voltage levels of each single battery cell, providing a good assessment of the overall health of the battery string. Even better, RTUs will monitor much more than just your UPS system. Just about every piece of telecom, transport, and switching gear you have will also benefit from external monitoring.

A good RTU will contain its own internal UPS with backup batteries large enough to continue operation for at least several hours after a power failure. Some of the top-quality RTUs will last for up to 10 hours.

1. Keep an Eye on Your Voltage Readings

Your battery monitoring system needs to provide you with continuous voltage readings. Without regular monitoring or at least control over the sampling rate, a problem can linger for too long before you're notified. That's why sampling your batteries at too long of intervals can be so problematic.

Your battery cells can easily become fully discharged between lengthy interval readings, which means you risk losing power at your sites and won't have any idea until the entire site suddenly goes dark. With real-time monitoring and customized interval samples, you can be assured you'll know about these kinds of emergencies before they bring down your vital network gear.

Battery Cell Voltage Chart and Trends on our Web Interface
Choose an RTU that can gather battery trending and performance data by issuing periodic SNMP GET requests. These trends will help you decide when it's time to replace individual cells or an entire string before you have a full-blown outage on your hands.

I've seen many clients roll out uninterruptible power supply monitoring systems at dozens of sites to protect the battery cells there from expensive damage. The battery monitoring systems that they deploy cover both VRLA (Valve-Regulated Lead-Acid) batteries and flooded batteries. Overcharging, at a level of 20 amps per 100 amps of battery capacity, is monitored carefully.

Monitoring voltage to prevent deep discharge is perhaps the most important role of the uninterruptible power source battery monitoring solution. As an example, if you discharge batteries at 48V and they drop to 42V, you have probably damaged the batteries.

You also want your battery monitor to have the ability to work with different battery types and voltages. All batteries are not the same. They have different orientations, connectors, and different voltage ranges - for instance, you might have a standard string of batteries or a string with four 12V cells and propriety connectors. You need a battery monitoring system that is very adaptable.

2. How Many Cells Do You Have?

Some battery voltage monitoring systems don't support the capacity to handle your large quantities of battery cells. It's absolutely key that you have the full support to monitor each of your battery cells. Otherwise, you'll find yourself vulnerable to the weakest link of the battery string.

Most of your vital sites will have A/B power battery systems. Look for a single device that is capable of monitoring both strings of batteries. Not all strings are created equal - so make sure your monitoring solution can monitor up to a 125 VDC string.

Tracking and logging the voltage levels of each single battery cell provides you a good assessment of the overall health of the battery string.

3. String Monitoring vs. Individual Cells

How important are your batteries to your network? With your up-time depending on your batteries, it's simply too risky to leave such a vital aspect of your network unmonitored. All it takes is a single bad jar or fully discharged battery and your entire network can come to a screeching stop. You need to be confident that your power system will remain running because you aren't there to monitor it.

Since a single bad battery jar can degrade the performance and lifespan of an entire array of batteries, it's critical you deploy a superior battery monitoring system. Monitoring the entire string is better than no monitoring at all - but it's not the most effective way to improve reliability. String voltage doesn't tell you how many cells have degraded and to what extent.

While some monitoring is better than no monitoring, having a good monitoring system will save you a lot of trouble in the future. Most systems have one sensor for the entire string of batteries. It may alert you that there is a problem. However, this system has no way of knowing which battery is causing the problem.

And that's the best-case scenario. In most cases, one battery will go bad, but the others on the string will pick up the slack. This puts a strain on the remaining batteries, but you're never notified because the sensor reads that everything is in working order.

A good battery monitor will have sensors to monitor each of your cells individually - looking not just for low voltages - but a difference between the cells and the average of all the cells. A system like this will not only save you network downtime but will also preserve the lifespan of your batteries.

4. Monitor Not Only the Voltage but Also Temperature

Since your UPS system is the first line of defense when commercial power fails, it's critical that you know how much power you have remaining. You can tie the string output voltage to the RTU for monitoring, and your RTU will extrapolate "battery life remaining" from that voltage measurement.

In fact, some of the better RTUs will have their power inputs internally tied to an analog circuit. This reduces your wiring requirements, as the very same wires that are supplying battery-plant power to your RTU are also being monitored for voltage.

Battery temperature is also a good general measure of battery string health. A temperature that rises too high is a strong indicator that something may be wrong.

Analog Senor Monitoring with four software thresholds
Look for ups battery monitoring software that support threshold values. Ideally, you'll have four software thresholds. This allows you to specify both major and minor variants of high and low-temperature alerts. While a minor high-temperature might warrant continued monitoring and a routine response, a major high-temperature should most likely trigger an emergency response to prevent thermal failures and expensive gear damage.

There are some very granular battery-monitoring systems available that tie a sensor pod to every cell in your battery string. But these tend to be quite expensive - to the point where many people say "I could replace my entire battery string for less than what that monitoring system costs."

A pair of analog inputs (one for each voltage and temperature) is a good monitoring technique that you can install at a relatively small cost.

There are some very complex ways to measure your batteries (sensor node on every cell, capacitance, internal resistance, etc.), but the simplest and easiest way to start is to track voltage to monitor battery life remaining, plus temperature to detect overheating before damage occurs.

NetGuardian 216 with Temperature Sensor Probe Diagram
This application features a single NetGuardian 216 along with the Temperature Sensor with Probe. The NetGuardian 216 will use the Temperature Sensor with Probe to monitor your large scale batteries. It'll be able to report alarms via SNMP over IP to your SNMP Manager.

5. Make Sure to Get the Alert Method You Need

It doesn't matter the size of your company, a flexible range of notification options gives you effective reporting methods.

When you go with DPS products, battery threshold alarms can be reported in the following ways:

  • Via SNMP to a network manager,
  • Directly to you - via text messages, or email notification
  • To your T/Mon master station,
  • Or, viewed directly from your NetGuardian's web interface.

When it comes to monitoring your batteries - and therefore protecting your up-time - you want true flexibility. Having the capability to receive 24/7 alerts (via text message, email, voice alerts, etc.) about the status of your batteries can be the difference between a power outage and keeping power to your gear.

Even if you have a 24/7 dedicated NOC (Network Operations Center), receiving on-the-fly and mobile alerts from your battery monitoring system can give you an edge in avoiding preventable outages. If you do not have an uninterruptible power supply with email notification, Look for a battery monitor that can alert you via emails, text messages, paging, etc. With notifications that can reach you even when you're out of the office, you can be assured you won't be left in the dark.

Learn more about battery monitoring with our white paper - Monitor Your Battery Cells for Superior Reliability. Download it here.

6. Having a Web Interface is Key to Managing Your UPS Monitoring System

When looking for UPS monitoring systems, make sure to get a device with a web browser interface that will present you with powerful remote control and monitoring tools. Instead of driving all the way out to your site to configure or manage your device, you'll be able to do it right from your desk. This can save money on fuel costs and expensive man-hours.

Your company might be large, you might also have an enterprise-grade SNMP manager, but a web interface lets you drill down when you need to. An intuitive and easy-to-use web interface is way above any other method to manage your battery monitoring.

UPS monitoring
The BVM has a web interface that allows you to easily monitor and manage your battery cell sensors.

Make Sure to Get the Best Battery Monitoring Technology

Do you know the status of your remote site battery strings? Would you know if one single cell was falling out of its ideal voltage or temperature range? At many companies, battery cell monitoring is a commonly overlooked opportunity to reduce costs and improve reliability.

This actually creates a huge problem. If you've ever had battery failures in the past, you know just how painful they can be. A single bad cell can greatly affect an entire string of batteries if you don't catch it early. An entire site can go dark if your batteries aren't working properly or become fully discharged.

Remote battery alarm monitoring and control isn't always as simple as slapping a single voltage monitor on each string. To really know the big picture, you need a high level of detail.

Fortunately, you can always count on the BVM G3. It integrates battery sensing into remote alarm monitoring. This creates a single unit that gives you the capability to monitor alarms from your equipment, environmental conditions, and battery strings.

Client testamonial
Don't just listen to us! DPS clients have positive reviews of their experience with our products.

Here are the main features of the battery monitoring system itself:

  • It consists of 1 sensor for every 2 batteries in the string and a "Sentinel" unit that connects to the sensors which relay alarms and information about the battery status to the RTU.
    With this system, you can monitor up to 160 cells per string and up to 16 strings. This gives you a maximum capacity of 1280 batteries per Sentinel unit (an extreme example, but at least you know you're covered). Also, up to 16 Sentinels can be strung together.
  • Sensors are placed at the battery cells to transmit the battery data to the Sentinel.
    The Sentinel unit interfaces with the RS485 port on a NetGuardian. The battery cell information is collected and reported by the NetGuardian to you. Simple wiring harnesses minimize the installation time for attaching the sensor modules to your batteries.
    Whether you have 2V or 12V cells (or something in between), the BSM gives you complete visibility over battery inductance, voltage, temperature, and inter-cell connection integrity (resistance). This helps protect your equipment from overheating, sparking, and even explosions. Each of these will damage your gear, cause serious injury, or potentially burn down your facility. By monitoring these values with the BSM, you're ensuring the safety of your gear, staff, and building.
  • Each battery sensor is capable of monitoring up to two jars - making it a thorough, yet cost-effective solution.
    Communication between the Sentinel and sensor is simple with just one wire in and one wire out - meaning you'll get a clean setup without having to run a bunch of cables. This means you will not only know if there's a problem but also you'll know which sensor is reading the error and which battery is producing it.

This battery monitoring solution gives you complete visibility over battery conductance, voltage, temperature, and resistance. These proven key indicators will give you advance warning of deteriorating battery cells. This means you can avoid being blindsided by a faulty or fully drained string.

If you need more than a handful of RTUs, it's important to deploy an efficient master station. The T/Mon LNX is the best option if you want a cost-effective monitoring solution.

UPS monitoring system
To keep an eye on your UPS system, and to guard against expensive downtime and otherwise preventable equipment failure, implement our robust system for fault detection.

Your Next Step: Learn More About Battery Monitoring

Monitoring UPS systems is an important part of any truly reliable network. You simply can't afford to leave your battery strings vulnerable. While some monitoring is better than no monitoring, the right monitoring system makes all the difference. If you want to get more information about how to monitor your UPS system, or want to speak with me or someone on my team about designing a monitoring solution for your network, please contact us today.