If your power
goes out, how can you
be sure your Uninterruptible Power Supply (UPS) and its batteries
will provide uninterruptible power?
The UPS
is specifically designed to protect and support critical equipment
through commercial power problems such as surges, brown outs, and
complete power outages. The UPS has two sources of energy - Commercial
Power and DC energy stored in Batteries. The UPS stores DC energy
in Batteries and then uses the batteries as an alternative power source
when commercial power fails.
The UPS is reliable by design however, the number one reason for
UPS failure is poor battery performance. Batteries are a critical
part of every UPS, but are too often the most overlooked component.
The most commonly used battery in UPS applications is Valve Regulated
Lead Acid (VRLA). To overcome the potential unreliability of VRLA
Batteries, the following guidelines are recommended:
Multiple Strings of Batteries: Given the fact
that batteries are unreliable, multiple strings of batteries in
parallel are recommended to ensure reliable battery backup during
a power outage. A single string of batteries in a UPS are like links
in a chain, if one battery in the single string fails the rest of
the batteries in the string are useless. With multiple strings in
parallel, if one battery in one string fails, the second string
will support the UPS.
Run Time on Batteries: How much time is needed
to shut down all equipment in the event of an extended power outage?
Once determined, this will be the amount of time the UPS will require
in battery run time.
Battery environment and usage: Ensuring
that the environment of the batteries meet the manufacturer's specification
is critical. Four factors will cause batteries to fail prematurely:
1. Temperature. Batteries require
the optimum temperature of 77° F. Every
degree over 77° F shortens the battery life expectancy.
2. Usage: Frequent power outages encountered by
the UPS shorten the life of the batteries. Example: Look at the
battery like a loaf of bread. The loaf of bread has only so many
slices. Every time a slice of bread is removed the loaf gets smaller.
It is the same with batteries; every time the batteries are used
the capacity decreases.
3. Sizing: The battery size needs to match the
application of the UPS requirements. If the batteries are undersized,
they may perform poorly.
4. Age: The age of the battery is determined by
the numerical age (months or years) as well as the above three factors
(Temperature, Usage and Size). Life expectancy is 3-5 years.
Battery Maintenance: Because VRLA batteries can fail without warning, it is recommended they be tested at regular intervals for proper operation. Any battery with test results outside of manufacturer specifications should be replaced.
For safety reasons, only trained and experienced technicians should perfom battery testing. |
