MK Battery Manual

2
What is the difference between VRLA
batteries and traditional wet batteries?
Wet batteries do not have special pressurized sealing vents, as they
do not work on the recombination principle. They contain liquid
electrolyte that can spill and cause corrosion if tipped or punctured.
Therefore, they are not air transportable without special containers.
They cannot be shipped via UPS or Parcel Post or used near
sensitive electronic equipment. They can only be installed “upright.”
Wet batteries lose capacity and become permanently damaged if:
• left in a discharged condition for any length of time (due to
sulfation). This is especially true of antimony and hybrid types.
• continually over-discharged, due to active material shedding.
This is especially true of automotive starting types.
Our gel cells have triple the deep cycle life of wet cell antimony alloy
deep cycle batteries, due to our unique design. The shelf life of a
VRLA battery is seven times higher than the shelf life of a deep cycle
antimony battery.
How do VRLA batteries recharge?
Are there any special precautions?
While our VRLA batteries accept a charge extremely well due to their
low internal resistance, any battery will be damaged by continual
under- or overcharging. Capacity is reduced and life is shortened.
Overcharging is especially harmful to any VRLA battery because of
the sealed design. Overcharging dries out the electrolyte by driving
the oxygen and hydrogen out of the battery through the pressure
relief valves. Performance and life are reduced.
If a battery is continually undercharged, a power-robbing layer of
sulfate will build up on the positive plate, which acts as a barrier
to recharging. Premature plate shedding can also occur.
Performance is reduced and life is shortened.
Therefore, it is critical that a charger be used that limits voltage.
The charger must be temperature-compensated to prevent under-
or overcharging due to ambient temperature changes. (See Charging
Voltage vs. Ambient Temperature chart on page 11.)
Important Charging Instructions
The warranty is void if improperly charged. Use a good constant
potential, temperature-compensated, voltage-regulated charger.
Constant current chargers should never be used on VRLA batteries.
Can VRLA batteries be installed in
sealed battery boxes?
NO! Never install any type of battery in a completely sealed
container. Although most of the normal gasses (oxygen and hydro-
gen) produced in a VRLA battery will be recombined as described
above, and not escape, oxygen and hydrogen will escape from the
battery in an overcharge condition (as is typical of any type battery).
For safety’s sake, these potentially explosive gasses must be allowed
to vent to the atmosphere and must never be trapped in a sealed
battery box or tightly enclosed space!
Can our VRLA batteries be used as
starting batteries as well?
Our VRLA batteries will work in SLI (Starting, Lighting and Ignition)
applications as long as the charging voltage is regulated to the
appropriate values from the tables on page 11. Many vehicle
regulators are set too high for gel batteries; therefore, the charging
system may require adjustment to properly recharge a gel battery
for best performance and life.
AGM batteries excel in low temperature, high current applications
such as cold weather starting.
What do the ratings and specifications
signify for this line?
All ratings are after 15 cycles and conform to BCI specifications.
CCA = Cold Cranking Amperes at 0°F (–17.8°C)
Cold cranking amperes equal the number of amperes a new, fully
charged battery will deliver at 0°F (–17.8°C) for thirty seconds of
discharge and maintain at least 1.2 volts per cell (7.2 volts for a
12-volt battery).
CA = Cranking Amperes at 32°F (0°C)
Same as above, tested at 32°F (0°C).
RC = Reserve Capacity at 80°F (27°C)
The reserve capacity is the time in minutes that a new, fully charged
battery can be continuously discharged at 25 amperes and maintain
at least 1.75 volts per cell (10.5 volts for a 12-volt battery).
Minutes discharged at 50, 25, 15, 8 and 5 Amperes
Minutes discharged is the time in minutes that a new, fully charged
battery will deliver at various currents and maintain at least 1.75
volts per cell. These are nominal or average ratings.
Ampere Hour Capacity at 20, 6, 3 and 1 Hour Rates
Ampere hour capacity is a unit of measure that is calculated by
multiplying the current in amperes by the time in hours of discharge
to 1.75 volts per cell. These are nominal or average ratings.
EXAMPLE
10 amperes for 20 hours (10 x 20) = 200 Ah @ the 20-hour rate
8 amperes for 3 hours (8 x 3) = 24 Ah @ the 3-hour rate
30 amperes for 1 hour (30 x 1) = 30 Ah @ the 1-hour rate
Therefore, if you have an application that requires a
draw of 17 amperes for 3 hours, you would need a 51
Ah battery (@ the 3 hour rate)…(17 x 3 = 51). However,
this is 100% of the capacity of this 51 Ah battery.
Most system designs will specify a battery that will deliver a
minimum
of twice the capacity required. This means the battery
will discharge to 50% of its capacity. Using a 50% depth of
discharge (versus 80% or 100%) will dramatically extend the life
of any battery. Therefore, when helping to specify a battery for a
system, choose a battery with at least twice the capacity required
for best performance. If 50 Ah is required, specify at least a 100 Ah
battery.