Batteries are the most critical component in the reliability of any UPS,
but they face three fundamental challenges.
All batteries need charging, but extended charging significantly shortens
battery life. Most batteries are charged via a trickle charging process
(a constant voltage feeding a low current to the battery). This method dries the
electrolyte and corrodes the plates, reducing potential life by up to 50%.
Batteries take time to recharge – users can't wait.
During prolonged power outages, the UPS batteries will discharge and not
recharge until the power returns. When there is subsequent power failure
before the batteries recharge, the computer will not have full back up time.
Overly rapid charging cancause premature battery failure, so the trick is to
charge at the fastest rate that is safe for the battery.
All batteries will eventually fail.
The question isn't "Will it happen?" but "When will it happen?"
Because UPS batteries are valve-regulated sealed lead acid, there has
been no practical way to provide the user with any meaningful advance
notice that batteries need to be replaced. In the past, the only way
to know when the batteries are dead is when the power fails and takes
your computer down with it. Until now, typical UPS batteries have
required replacement every two to three years.
Powerware's exclusive, patented advanced batterymanagement (ABM™) technology
solves these UPS battery problems. It doubles the life of the UPS batteries, provides
the fastest safe recharge time, and provides reliable advanced notice when the
batteries need replacement. By doubling battery life and virtually eliminating this
major cause of supply load crashes, Powerware is able to offer the industry's longest
and most inclusive warranties on all of its products that incorporate ABM™.
No other manufacturer can make this statement.
HOW DOES ABM™ WORK?
Three stage charging: ABM™ doubles battery life via three-stage charging
process. The patented microprocessor controlled technology rapidly charges the
battery via the following three steps:
Charge
A rapid constant current charge brings the battery to near full capacity in
approximately three hours compared to 15 or more hours with many other UPSs.
Float
Next, a constant voltage 'trickle' charge (of 2.3 volts per cell), similar
to that used in other UPSs, continues for approximately 48 hours or until
the batteries are solidly 'topped off.'
Rest
At this point, the charger is turned off.
The charger is turned on again when required due to use or natural decay
during extended periods of non-use. This means that UPSs with ABM™
technology are being charged on an average of a few minutes a day compared
to competitors' UPSs that are charged 24 hours a day every day.
Since UPS batteries use the same technology as car batteries, a simple
correlation can be observed. It is easy to see that car batteries, which
are charge only when the car is running, typically last two to three times
longer than traditional UPS batteries due to the 'rest' state that occurs
when the car is not running. If car batteries were constantly trickle charged,
they too would last less than two years.
To minimise the damage caused by excessive charging, some manufacturers use a
temperature compensating charger. However, this only lessens the problems, it does
not eliminate it. In fact, if the temperature sensing circuitry is not properly
calibrated, it may have no benefit at all. Simply turning the charger off avoids
these problems.
Advanced notification
ABM™ is the only technology currently available that reliably provides true
advanced notification prior to battery failure.
Other UPS manufactures primarily perform a simple check of the DC voltage level.
This indicates potential not capacity, letting the users know that the battery is
dead only after it is dead.
Because competitive systems use a constant trickle charge, these tests are
particularly unreliable since the voltage is tested only while the battery
is being charged, leading to false indications of a healthy battery.
Before the days of sealed, maintenance free batteries, one could check the battery's
electrolyte with a hydrometer to determine the batter's ability to retain a charge.
Now, with sealed batteries, the only way to measure the capacity of a sealed battery
is to discharge the cell. To accomplish this, ABM™ periodically initiates a
brief discharge cycle to check the internal impedance. Impedance is calculated and
compare to ideal. In addition, the open cell voltage and decay rate of the battery is
measured and compared to the expected capacity.
When any of these three tests detect a significant change from the normal, the
microprocessor indicates, well in advance, when the battery needs to be replaced.