As a leading provider in the tech industry, we’re always on the lookout for potential risks to data center infrastructure. We proactively search for strategies to assist our clients with efficient data center management and help them develop processes and solutions to minimize the potential for data center downtime and data risk.
According to a recent Uptime Institute report,1 the three most common causes of data center downtime are:
- Uninterruptible Power Supply (UPS) Battery Failure
- Network Failure Due to DDOS Attacks
- Software & IT Systems Issues
Today, we’re going to focus on the underlying reasons for UPS battery failure.
What is a battery backup/UPS system?
UPS batteries are electrochemical devices whose primary functions are to store and deliver power when called upon. Unfortunately, the UPS system’s ability to perform reliably depreciates over the lifetime of the batteries, so it’s fairly common practice in the data center industry to replace UPS batteries every three to five years. In addition to time, there can be other contributing factors that cause electrochemical devices to degrade at unexpected rates.
Common factors that degrade UPS batteries
- Improper Float Voltage
- Poor Storage Conditions
- Incorrect Application
Over-Cycling: Each time you utilize a battery to operate a UPS system during a power failure, the battery must recharge for its next use. Each discharge and recharge reduces the total capacity of the battery. Your system, which was sized and built for the appropriate capacity when it was installed, now potentially has a significantly lower capacity as it ages.
Improper Float Voltage: Inbound voltage fluctuations that occur when you’re recharging your UPS batteries also impact their performance. Low-voltage charging causes hardening of your battery plates and high-voltage charging causes internal dry out of the battery leading to thermal runaway and internal melting.
Poor Storage and Maintenance: Did you know that unused batteries are constantly discharging small amounts of energy? That’s why we advise clients to recharge unused batteries every three to six months. Otherwise, you’ll see a permanent reduction in capacity. Storing unused batteries at cooler temperatures (around 50 degrees F) has also proven to prolong their life.
Incorrect Application: UPS batteries are purpose-built for high discharge rates over short periods of time (usually 15 minutes or less). Often, IT personnel will size their UPS system with greater capacity to allow for longer run times during a power failure incident. Unfortunately, unless they’re specified by the manufacturer for longer discharge times, the plates of the batteries will overheat and fail during extended runs, even when the capacity of the battery has not been fully utilized.
UPS battery failure
Ultimately, any of these four battery degrading issues can lead to the most common cause of battery failure — cell dry out — which inadvertently results in an open circuit. Most UPS battery designs daisy-chain multiple cells in a single string to the UPS system DC-BUS. If just one cell in the string fails, the circuit is opened causing the entire string to lose current.
Looking for data center management best practices? Interested in ways to mitigate your risk of UPS battery failure? Check out our next post in this series about the top causes of data center downtime: managing your backup power strategy.
And, if you are currently designing your own UPS battery power supply solution, don’t hesitate to reach out to us for assistance.
We’re happy to provide suggestions and considerations to achieve your best UPS system design.