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Battery
storage, care & maintenance
The
storage or shelf life of a VRLA battery is usually between
12 and 18 months at 20°C starting from a charged condition.
Warning
- Never store in a discharged or partially discharged
state.
Always store in a dry, clean, cool environment in a fully
packaged condition.
If storage of 12 months or longer is required supplementary
charging will be required.
Design
Life
Float
Each battery type will have a prescribed float design life.
Please be aware of this life expectancy and replace the battery
as End-of-Life approaches. Keep a reference or label the battery
to show its date of installation to facilitate replacement
at the correct time. Factors other than time may affect the
life of the battery and this will be indicated by a reduction
in capacity. The battery should be changed when the capacity
is reduced to a level that will prevent it fulfilling its
required duty. This may be well in advance of its design life
if, for example, the ambient temperature is considerably above
20°C ie 30°C or more.
Cyclic
Each battery suited to cyclic use will reach End-of-Life after
a prescribed number of cycles. This number is dependant upon
the depth of discharge of each cycle. The deeper the discharge,
the less number of cycles to End-of-Life. Depth of discharge
is expressed as the percentage of the battery capacity required
per duty cycle.
Battery
Care
Each
Yuasa VRLA battery should be supplied in a charged condition
having passed stringent quality checks.
To ensure optimum battery performance and life, it helps to
take care of your battery by observing the following:
Sulphation/Undercharge
WARNING
- Never leave a VRLA Battery in a discharged state.
If a battery has an open-circuit voltage lower than its rated
value, then sulphation may well be the cause.
When
a battery is left in a discharged state or for prolonged periods
of storage, lead sulphate crystals begin to form acting as
a barrier to recharge and will prevent normal battery operation.
Depending
on the degree of sulphation, a battery may be recovered from
this condition by constant current charging at a higher voltage
with the current limited to one tenth of the battery capacity
for a maximum of 12 hours.
Note:
The applied voltage will exceed the normal recommendation
and so the battery must be monitored (not left unattended)
and removed from charge if excess heat is dissipated. The
voltage required to "force" this maximum current
into the battery will reduce as the battery recovers until
normal charging can take place.
In
extreme circumstances a battery may never fully recover from
sulphation and must therefore be replaced.
If in doubt call Yuasa Technical Dept 01793-645753
Overcharge
As
mentioned in Section 4 optimum charging relies mainly on voltage,
current and temperature factors which are interrelated and
all of which can cause overcharge.
Excessive
charge voltages will force a high overcharge current into
the battery, which will dissipate as heat, and may cause gas
emission through the safety valve. Within a short period of
time this will corrode the positive plate material and accelerate
the battery towards end-of-life.
Under
these conditions the heat produced inside the battery can
lead to thermal runaway due to the increased electrochemical
reaction within the battery. The battery may swell before
failing and will be irrecoverable from this state. This situation
is potentially dangerous.
Temperature
Warning
-
Heat Kills Batteries
The
recommended normal operating temperature is 20°C.
HIGH
TEMPERATURE will reduce battery service life often quite dramatically
(see figures 2 and 3). In extreme cases this can cause Thermal
Runaway, resulting in high oxygen/hydrogen gas production
and battery swelling. Batteries are irrecoverable from this
condition and should be replaced.
Figure
2
| Temperature
(°C)
|
20° |
25° |
30° |
35° |
40° |
45° |
50° |
|
%
Expected Float Life
|
100%
|
71%
|
50%
|
35%
|
25%
|
18%
|
13%
|
Notice
that high temperatures will give increased performance but
with a corresponding loss in life.
LOW
TEMPERATURES will help to ensure a long service life but batteries
used at low temperatures have reduced capacity.
For detailed information contact Yuasa Technical Dept 08708
500312
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