Batteries are the life support for your UPS and generator power systems. They protect you during power outages.
Power losses are difficult to predict. They can be caused by a number of factors including natural disasters, storms, poor power grid technology, and people.
So you say to me, “I have redundancy throughout my data center. I do PM’s on my batteries, so I am fine.” That’s great! However, neither of those will protect the weakest link in your facility – the batteries.
Batteries need to be well cared for so they’re ready to do their job when there is a power crisis in your facility.
In 2020 this is more important now than ever. As we navigate through the COVID-19 pandemic, an increased number of people working from home and students learning online have put an intense strain on data centers.
Businesses have suffered great losses from the Shelter-in-Place orders and restrictions placed on the way they operate. They can’t afford to lose more due to downtime in the data center.
The current pandemic has also caused many Data Center Managers to push their scheduled battery PM’s out several weeks or even months. This puts their UPS systems at greater risk of failure.
Keep in mind that batteries are chemical devices. Their state of health can change virtually overnight. Preventative maintenance and testing one day does not mean that they won’t fail the next day.
If I have a physical exam and bloodwork done today and am told that the results are good that doesn’t prevent me from coming down with an illness a few days later. The check up by my doctor didn’t prevent my illness anymore then a Preventative Maintenance can prevent battery failure hours or days later.
So, how do you protect this important life support?
Before we answer that, let’s first discuss what causes failures in the first place.
There are four main factors that affect the health of your batteries. Keep in mind that batteries have a limited life, and will show a slow degradation of capacity until they reach around 80 percent of their initial rating.
These four factors affect battery life no matter the size of the UPS or where is it deployed.
- Ambient Temperature
The rated capacity of a battery is based on an ambient temperature of 77 degrees (25 Celsius). Any variation to this temperature (up or down) can affect the battery’s performance and shorten its lifetime. For every 15 degrees F average temperature over 77F can reduce the battery life by 50 percent.
All batteries will require replacement after a certain period of time. They are electrochemical devices and their ability to deliver power and store energy decreases over time; regardless, of following manufacturer guidelines for proper storage, usage, and maintenance.
The UPS operates on battery power during an outage. The battery is recharged for future use once the power is restored or it is switched to generator power. This is called a discharge cycle. The capacity of the battery is reduced slightly with every discharge and recharge cycle. The length of these discharge cycles determines the reduction in battery capacity. The battery can only undergo a certain number of discharge/recharge cycles before the chemistry is depleted. Once this happens, the cells fail and the battery must be replaced.
Batteries need to be maintained on a regular basis. Without maintenance and proper battery management, your UPS battery may experience heat-generating resistance at the terminals, improper loading, reduced protection and premature failure. Proper continuous battery management can extend the life of the battery string and identify bad batteries before they affect the other batteries.
Conditions of Battery Failure
Below are 7 conditions and the causes of data center battery failure:
- Sulfation of Plates
Sitting discharged for an extended period, not on charge or being undercharged, such as battery shelf life being exceeded past manufacturer’s guidelines.
- Plate Separation
Repeated cycling (charging and discharging), damage during handling and shipping, and overcharging.
- Grid corrosion
Normal aging, operating in an acidic environment and high temperatures.
- Internal Short Circuit
Heat (plates expand causing shorts), separator failure, handling and shipping, and grid corrosion
- External Short Circuit
Human error (shortening terminals) and leaks
- Excessive gassing
Often due to high temperatures or overcharging; electrolyte volume is decreased
- Drying Out
Excessive gassing, high temperatures or overcharging, resulting in too little electrolyte for battery to function and provide full backup time
Source: Eaton Corporation – The Large Handbook of Batteries
In our next post, I’ll be addressing eleven ways to protect your data center batteries.