Don’s Corner: “Why Aren’t My Batteries Lasting As Long As They Used To?”

Posted by on June 14, 2012

Don Melchert, Critical Facility Specialist

Why aren’t my batteries lasting as long as they used to?

Scenario: Your trusty UPS has been providing faithful service for the past 8 years.  Maybe it’s had a couple of minor repairs, like fan replacements and a capacitor upgrade, but other than the full battery refresh during the 5th year, “Old Faithful” has been holding up its end of the bargain.  Lately though, it seems as though the batteries just aren’t what they used to be.  It couldn’t be the data center’s fault, could it?  Nothing’s really changed in there…well, maybe the legs were balanced after the load increased from 50% to 65%, but the room is still stable at 73F and the utility power has actually improved over the years.  However, now the UPS is displaying a “Battery Weak” alarm only after 3 years of service.  How could this be, and what is there to be done about it?  To answer those questions requires a basic understanding of the underlying issue: battery quality.

The first question’s easy to tackle and has a clear answer, so let’s start there.  Years ago, batteries weighed more, simply because they were made from quality ingredients, more specifically, there was more lead.  With changes in manufactures, factory locations and most importantly, battery quality has taken a turn for the worst.  Don’t believe me?  I have a simple experiment for you:  For the first, grab a small, 7.2AH battery made before 2006, and an equivalent battery made in 2011.  Weigh them separately and see what you find.

I think it’s safe to say that these days, Superman would be having a much easier time seeing what’s in Lex Luthor’s data center!

It’s as simple as this… lower levels of lead are being used in the construction of new batteries, and so the likelihood of getting a battery to last more than 3 years is few and far between.  Oh, the charge rate is the same (battery reaches set charge voltage), even the discharge rate is the same (time before the low limit is reached), but it’s the number of discharge cycles that has changed.  A typical deep-cycle battery delivers 100–200 cycles before it starts the gradual decline to its ultimate failure.  At less than 75%, this same battery will begin to decline exponentially faster.  Unfortunately, for the critical data community, this means we are forced to either accept the fact that we’ll be changing our batteries sooner, or we accept the fact that in order to get the same quality we’ve grown accustomed to, we’ll have to pay a premium to have it.

Hey, I never said this would be a feel good post!  Never fear though, doom and gloom isn’t my style, so, let’s see what we can do to turn it around…

Since the mission of a data center isn’t likely to become, “…provide data to end-users when it’s convenient…”, we have to decide if we want to put our time and money into maintaining our batteries, or just throwing more money at the problem.  From my standpoint, it’s always better to take better care of what you have now, rather than ask for more money from the Bean Counters before a total battery failure.  I can hear you now, “What does that mean?”  It’s easy…get a battery PM performed now!  If a battery is found to be below acceptable limits (75% capacity), don’t just replace it with the lowest bidder.  Take some time to work with a reputable source to determine which battery is best for your particular situation.  Even if the technician finds nothing wrong at all, be sure to schedule another inspection before he or she leaves your facility.  Will you pay a little more? Possibly, yes, but it’s called Preventative Maintenance for a reason, and prevention is always cheaper than what comes after making that call to your CEO that starts off something like, “Sir, our network is down because…” How often to have battery PMs performed depends on how old the batteries are and how well they’re treated.   In doing so, you’ll be able to weed out the batteries that aren’t playing well with others before a total battery failure occurs.

And let’s be honest, when does that ever happen during normal business hours?

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