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12.4 Function
When you call up the "Function" menu you see the display window
shown in Fig. 19, with "Select Function" in the bottom half. Once again,
you can use the jog dial or the arrow buttons to select the desired
processing function; all the functions described in detail under 12.4.1
to 12.4.8 are available. The selected function is shown in the central
area of the top half of the screen.
12.4.1 Charge
When the Charge function is selected, the ALC 8500-2 Expert charges
the battery connected to it according to the set values. It is not ne-
cessary to discharge the battery before the start of the charge process, as the battery will be charged
up to 100% of its actual capacity regardless of any residual charge which may be present. Note that
new batteries are sometimes capable of accepting more energy than their stated nominal capacity,
whereas older batteries will generally fall short of this.
When you have entered the battery data and selected the "Charge" function, press the "Start" button
to initiate the charge process. As long as the connected battery is on charge, the main window will
display the corresponding symbols. When the battery reaches its maximum effective capacity, the
screen displays the "Charged" symbol, and a text message that the charge process is concluded
appears in the channel window. The charged-in capacity can be read off in the top half of the
screen.
The charger now switches over to trickle charge of unlimited duration, designed to compensate for
losses due to the self-discharge process. This means that it is permissible to leave the pack connec-
ted to the (switched-on) charger for an indefinite period.
12.4.2 Discharge
When this function is selected, the battery connected to the ALC 8500-2 Expert is discharged down
to the final discharge voltage appropriate to the pack; the capacity removed from the battery is dis-
played on the graphic screen.
12.4.3 Discharge / Charge
First the ALC 8500-2 Expert initiates a discharge process in order to pre-discharge the battery con-
nected to it. When the battery has reached the appropriate final discharge voltage, the charge process
starts automatically at the programmed charge current. We recommend that you always pre-dischar-
ge your NC batteries before charging them, as the process reliably eliminates and prevents the me-
mory effect.
When the charge process is concluded, the charger again switches to the trickle charge function.
12.4.4 Test
The Test function is designed for measuring battery capacity. Battery capacity should generally be
measured under defined nominal conditions, as the quantity of energy which can be removed from a
pack varies according to a number of factors, including the discharge current employed. It is often
the case with NC cells that the stated nominal capacity applies to a discharge current corresponding
to 20% of the battery's nominal capacity (C/5). For example, a 1 Ah battery would be discharged at
a current of 200 mA in order to measure its capacity.
The first step in determining the capacity of the pack is to charge it completely. A full discharge process
is then carried out under the previously defined nominal conditions; the capacity removed from the
pack is measured continuously until its voltage falls to the final discharge value.
When this function has been completed, the battery is recharged with automatic transition to trickle
charge.
47
Fig. 19: Selecting
the desired function
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