User Manual

24
Sulfation and Freezing
The two most common reasons that batteries can become damaged
are sulfation and freezing. These are not a problem if the battery is
properly charged, and for Conventional batteries the water level is
maintained. Battery sulfation takes place for two reasons: continuous
discharging, or low electrolyte levels. When a battery discharges the
lead in the plates turn into lead sulfate. The lead sulfate is actually
a crystal which grows larger when the discharge is continuous and
uninterrupted. In a Conventional battery, low electrolyte levels
expose the cell plates to air causing the lead material to oxidize and
form sulfates. In either case it doesn’t take long before the battery
won’t hold a charge. Low electrolyte levels cause another problem
because the acid in the electrolyte becomes more concentrated,
causing the active material
to corrode and fall to the
bottom of the battery case.
If this conditions takes
place over a long enough
time period the process
will internally short out the
battery.
For added protection,
YUASA’s YuMicron and
AGM batteries are treated
with a special chemical
formula called “Sulfate
Stop.” This dramatically
reduces sulfate crystal
buildup on cell plates
resulting in longer
battery life. For example,
Yuasa conducted a test on two batteries; one with Sulfate Stop,
and the other without. Both batteries were under the constant
discharge of a
10-watt bulb for a week. The battery with Sulfate
Stop was charged with a
90% recover rate. The untreated battery
could not be charged enough to put it back into service.
Freezing is not a problem with a fully charged battery.
However if the battery becomes discharged (and the acid in
the electrolyte turns into mostly water) the electrolyte will
freeze. Freezing can cause a condition called “mossing” which is
indicated by small red lines on the battery plates. Freezing can
also crack the battery case and buckle the plates permanently
damaging the battery. A fully-charged battery can be stored at
subfreezing temperatures with no damage. As the chart on this
page indicates a fully charged battery will not freeze unless
the temperature drops below
-75° F. By contrast a discharged
(dead) battery will freeze at only
27° F. That’s a difference
of more than
100 degrees between the low temperatures a
charged and discharged battery can withstand.
Electrolyte Freezing Points
Specific Gravity
of Electrolyte
Freezing
Point
1.265
1.225
1.200
1.150
1.100
1.050
-75°F
-35°F
-17°F
+5°F
+18°F
+27°F
A battery that is fully charged can be
stored at low temperatures without
freezing. This chart shows that as
specifi c gravity (state-of-charge)
decreases, the battery will freeze at a
higher temperature.
POINTS TO REMEMBER
■ Inspect battery terminals, screws and cables for breakage,
corrosion or loose connections
■ Inspect the battery case for damage including cracks or
leaks
■ Check electrolyte level on Conventional batteries and add
water if necessary
■ Never add water to an AGM battery
■ State-of-Charge can be tested on a fully charged battery
using a voltmeter
■ A vehicle’s starter motor can be used for battery load testing
■ For peak performance never let a battery sit discharged for
long periods of time