3550 Battery HiTESTER Series
15
Q3. What is the relationship
between the charging interval
and the internal resistance, and
between the number of cycles
and the internal resistance?
A3. When a battery is charged for a long time, or
as the charging/discharging cycle is
repeated, the discharge capacity of the
battery decreases due to corrosion on the
plates and loss of electrolytic solution. An
example discharge curve is illustrated below.
The curve differs according to the battery
type. It is also said that temperature has an
effect on how fast a battery deteriorates.
Q4. Does the AC signal used for
measurement cause battery
deterioration?
A4. Normal small- size batteries and larger
batteries will not be affected, because the
measurement current is very small (50 mA)
and the 1 kHz AC signal does not cause a
chemical reaction in the battery.
Q5. What is the importance of the
specific gravity?
A5. For wet- type lead storage batteries and
alkaline storage batteries, the temperature of
the electrolytic solution and the specific
gravity are measured and used to evaluate
the deterioration of the battery. Specific
gravity is measured with a densitometer, but
because the value changes according to the
temperature of the solution, this value is
customarily converted to the value at a
temperature of 20°C and then compared to
the value specified by the manufacturer of
the battery. If the specific gravity is low, it
indicates that the battery is depleted and that
its discharge capacity is low. The internal
resistance of the battery tends to be high in
this case. Conversely, if the specific gravity
is high, it indicates that the battery is
overcharged.
Q6. What types of batteries can be
tested by the 3550 series?
A.6 Basically, the 3550 series can be used to test
any type of battery. However, batteries with
a resistance of several hundred mΩ, such as
button- type batteries, will be out of range.
The 3550 series also can not be used to test
batteries with a total voltage of 50V(3551:60V
DC) or more, such as batteries used in
industrial machinery. Although lithium ion
batteries can also be tested, those that are
part of a package are connected in series to
a PTC device as a safety mechanism. This
device has an internal resistance of over
100mIn addition, there is also an FET for
current control that is inserted in the path of
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