Not everyone understands that, though. As a result,
some of the many factors that can detract from battery performance tend to get overlooked. Want to
know what you may be missing? Here’s advice from
industry insiders on what to watch for—including a
few things you might never have thought of.
x Temperature. Temperature—both high and
low—has an enormous impact on battery performance. As you might expect, a battery can be
destroyed if it should freeze. But even moderately
low battery temperatures will decrease capacity. At
30 degrees F internal temperature, the available battery capacity is reduced by roughly 30 percent, says
Bill Rubenzer, vice president, sales and marketing
at industrial battery manufacturer Storage Battery
Systems LLC. Even at 50 degrees internal temperature, a 1,000-ampere-hour battery will act more
like a 600–700 amp-hour unit, according to Tony
Amato, executive vice president of battery distributor Industrial Battery Products Inc.
When the battery temperature falls below 40, the
voltage will appear artificially high and a battery
discharge indicator (BDI) will show more power
available than there actually is, says Steve Spaar,
marketing director–Americas for the battery manufacturer EnerSys, which also owns Douglas brand
batteries. At low temperatures, the charger will also
see the voltage as artificially high and will shut off too
soon, which leads to shorter battery life.
There are ways to counteract the effects of frosty
temperatures. One option for extremely cold environments is to insulate the battery compartment.
Another is to use a battery with a high amp-hour
capacity. It’s possible to raise that capacity in an
existing battery by increasing the acid content in the
electrolyte solution (the mix of water and acid that
governs the battery’s electrochemical reaction and
thus, its voltage). However, Amato warns, there’s
a trade-off: You’ll get more run time per shift, but
you’ll also be shortening the battery’s useful life by
potentially as much as two years.
A battery with tubular positive plates will have more
usable capacity than an equivalent flat-plate-con-
struction battery, and so should be considered for
cold applications, Rubenzer says. Not just batteries
but also chargers should be specifically designed for
low temperatures, and battery discharge indicators
should be adjusted for cold conditions.
Sustained high battery temperatures can do serious damage. Battery life can be reduced by as much
as 50 percent for every 15-degree increase over 77,
based on average temperatures. As a battery’s sustained temperature increases, moreover, the loss of
battery life accelerates.
Battery heating is caused by the resistance of the
intercell connectors while a vehicle is in use, according to PowerDesigners, a manufacturer of battery
chargers and monitoring systems. Additional heating
due to this same effect occurs during charging, and
the higher amperage used during opportunity and
fast charging exacerbates the problem, the company
says. Because there’s no cooldown period following
the charge, as in a conventional charging application,
the battery remains hot.
Hot air temperatures can also lead to overheating,
especially in fast and opportunity charging operations. PowerDesigners explains it this way: While
it is in use (i.e., being discharged), a battery usually
will be warmer than ambient temperatures. As the
ambient temperature rises, the air becomes less effective in cooling the battery, and the battery’s internal
temperature will rise. Charging will further raise the
battery’s internal temperature—possibly to the point
where the battery could suffer damage if you’re not
careful.
For example, discharging typically adds about
15 degrees to the battery temperature. At an ambient temperature of 75, then, discharging will add
enough heat to raise the battery’s temperature to
90. Charging will add another 10 degrees, bringing
the battery’s temperature to 100. When a battery
reaches 130 degrees, the charger will issue a “battery
over temp” fault and will stop the charge to prevent
battery damage. In this case, the battery has a margin
of 30 degrees before that happens. But at an ambient
