what you know about a battery’s volts, amps, and ampere-hours,
you’re ready to easily change those numbers into the final key
concept, watts.
Watt,
W.
: Using battery voltage or amperage alone doesn’t tell you
enough about the battery. Multiplying those two values together
does. The answer you get is a battery’s wattage: the electrical power
a battery can provide. Every 1,000 watts is a kilowatt, or KW. Then,
for example, when your forklift needs 10KW of continuous power for
a 6-hour shift, you need a battery that provides 60 kilowatt-hours
(60KWH) of energy.
OTHER IMPORTANT
BATTERY CONCEPTS
Cycle:
Every time a battery is charged and then discharged in use is
one cycle. Battery life is usually measured in cycles. 1,200 to 1,500
cycles, or 5 to 6 years, is about the average battery’s life. However,
battery maintenance and charging procedures will either prolong or
shorten battery life, depending on how well recommended
procedures are followed. EnerSys will provide training aids and
materials whenever asked. Also, when a battery’s average voltage
measures less than 2.08 volts (open circuit - after a full charge) times
the total number of cells, the battery either needs repair or has
reached the end of its life. To be sure the situation isn’t the result of a
maintenance problem, call your lift truck dealer or EnerSys
representative.
Specific Gravity:
As a battery is used, the sulfuric acid in the
electrolyte changes into another chemical when it combines with
the active material. As a result there’s less and less
power-generating sulfuric acid as the battery is discharged.
When the battery is recharged, the sulfuric acid returns.
FIGURE 1
CHARGED/
RECHARGED
DISCHARGING
DISCHARGED
1.300 Specific
1.200 Specific
1.120 Specific
Gravity
Gravity
Gravity
Sponge Lead
Water
Lead Peroxide
Lead Sulfate
Sulfuric Acid
The hydrometer detects the chemical change by measuring the
ratio of sulfuric acid to water. In addition, temperature also affects a
battery’s specific gravity. Temperatures above and below 77° F
require correction of the hydrometer reading. EnerSys can provide
a thermometer which shows how much to correct for the
temperature at your location.
Gassing:
Gassing occurs when chemical activity and heat build up
during overcharge, the last 20% of a normal charging cycle. The
water in the electrolyte inside the battery breaks down into hydrgen
and oxygen. When this happens, electrolyte will bubble and
expand, causing the battery to overflow if any cell was previously
filled with too much water. Inexperienced maintenance personnel
should never try to replace lost sulfuric acid. In addition, even
worse than overwatering is underwatering. If electrolyte isn’t at
least up to the battery’s splash plate during charging and use, part
of the plates will be unused. The battery will then overheat, gas
more violently, and the exposed plates will eventually dry out and
be damaged. Scheduled maintenance must be done if a battery is
5. CONSTRUCTION
Fig. 2 illustrates the construction of a typical motive power
cell of the tubular design.
Figure 2
Call-outs as follows:
1. Positive Post
0
7. Separator
2. Negative Post
0
8. Vent Cap
3. Positive Plate
0
9. Jar
4. Negative Plate
10. Cover
5. Negative Grid
11. Bridge
6. Positive Spine
12. Vent Well
6. INSPECTION OF THE
BATTERY UPON RECEIPT
a. Examine for physical damage or loss of electrolyte.
b. Report actual or suspected damage to carrier.
c. Give battery an equalizing charge. (See Section 13.)
d. Check electrolyte levels IMMEDIATELY after charge and
add water if needed.
e. When adding water, the electrolyte height should be as
specified in Section 17.
7. MOIST/DRY CHARGED
BATTERIES
1. Moist charged batteries are electrically live upon receipt, even
before filling with electrolyte. Do NOT lay any metallic objects on the
battery.
2. Moist charged batteries or cells should be activated (unsealed,
filled with electrolyte and charged) only when ready to be placed in
service. Until ready for use, they must be stored in a cool, dry, low
humidity location with the pressure relief valves/vent plugs tightly in
place. Moist charged cells must be activated within 24 hours of the
loosening/breaking of the seal of the pressure relief valves/vent plugs.
CAUTION:
IF THE EXISTING VENT PLUG HAS A LABEL
MARKED “DO NOT REMOVE”, STOP ALL ACTIVITY AND
CALL YOUR LOCAL ENERSYS REPRESENTATIVE.
3. To prepare for use carefully remove the sealed PRV
(pressure relief valve) using an approved tool or if necessary a
widegrip pliers, taking care not to damage the cell vent well
exteri-or. THROW AWAY THE PRESSURE RELIEF
VALVE/ VENTPLUG. Fill all cells with electrolyte 0.015 sp. gr.
lower than the nominal operating gravity.
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