DC Velocity - IdeaBook 2014

temperature of 90, the battery begins charging at 105 degrees (90 + 15). The added heat from charging ( 10 degrees) coupled with the reduced cooling effect of the higher ambient temperature could potentially cause the internal temperature to rise high enough to trigger a “battery over temp” fault.

Making sure battery charging areas are well ventilated to provide good air movement will help to minimize average battery temperatures, according to Aerovironment, the manufacturer of PosiCharge fast charging systems. For battery changing systems, make sure there is a cooldown period after charging and use a first-in, first-out (FIFO) rotation. For opportunity charging, consider using ventilated battery trays or some type of active cooling, such as blowing air.

Temperature will affect cells differ-
ently depending on the battery layout
or position in the lift truck, causing
some cells to be overdischarged while
others are underdischarged, notes Ken
Sanders, director of motive power
battery engineering for East Penn
Manufacturing Co. Inc., maker of
Deka brand batteries. A weekly equal-
izing charge—an extra-long charge that
brings each cell in the battery up to the
same, maximum capacity—will allow
battery and cell temperatures to reach
a state of equilibrium, thus minimizing cell-to-cell
temperature variations and improving battery perfor-
mance and longevity, he says.
x Failing to equalize. Batteries should be equalized
once a week, says Amato. Unfortunately, that doesn’t
always happen as scheduled, due to poor mainte-
nance tracking or because with chargers that are set
to automatically do an equalizing charge, users tend
to assume everything is happening as planned. But
that’s not always a safe assumption, Amato warns. In
a facility that rotates multiple batteries, “the batteries
don’t always get on that charger the right day or time,”
he says. A battery tracking and monitoring system that
alerts managers when a particular battery has not been
equalized is one possible solution.
x Improper watering. Overwatering, underwatering,
or watering at the wrong time will lead to a host of
problems that can shorten battery life. These include
plate oxidation and capacity loss; inadequate electro-
lyte levels; drying out and overheating; reduced amp
hours, which can lead to overcharging and overheat-
ing; and boilovers, resulting in acid damage to battery
tops, equipment, and floors (and potentially person-
nel) and requiring a costly acid adjustment.

Battery manufacturers recommend filling after an equalizing charge. Because the electrolyte expands when the battery is in use, watering after a charge helps to prevent overfilling and boilovers, say the folks at Flow-Rite Controls, a supplier of battery watering systems. It’s best to fill on a regular schedule: weekly for heavy-use applications and less frequently (perhaps as little as once a month) for light-use applications.

Manually filling individual cells correctly—adding neither too much nor too little—is not easy, and the process typically takes around 15 minutes. Single-point watering systems maintain reliable electrolyte levels and take less than a minute, according to Flow-Rite and other providers of watering systems. These systems consist of automatic shut-off valves connected to tubing, which replace the battery’s vent caps. Once the tubing is connected to a water supply, water flows into each cell until it reaches the correct level. When using a single-point watering system,

be sure to regularly check the system valves to prevent
potential clogs.
x Overdischarging. Regularly overdischarging—
allowing a battery to dip below 20 percent state of
charge—will damage the battery, causing prema-
ture capacity loss and shortening its life span. One
increasingly common reason operators overdischarge
batteries is that lift trucks are traveling faster and are
lifting heavier loads higher and more quickly than in
the past, which places greater demands on the battery.
This is particularly true of trucks with the newer alter-
nating current (AC) motors, which pull more current
out of the battery than their direct current (DC) coun-
terparts. “You’re getting 10 to 15 percent more work
out of [an AC] truck, but the battery technology is still
the same,” Amato says. “That means you’re using 10
to 15 percent more power in the same time frame.”