elv ALC 7000 Operating Instructions Manual page 26

4. Charging Process, Charge Outputs
During the charging process, the microcontroller monitors the voltage supply at
each individual charge connection. The charge curve is evaluated by means of
several successive measured values.
In order that transmission resistances at the connection terminals do not affect
the measured result, the battery voltage is scanned in a currentless state.
In the case of NiCd and NiMH batteries, the end of charge detection occurs
according to the particularly accurate method of negative voltage difference at
the end of the charging characteristic. The battery has stored the maximum
amount of energy possible when a voltage drop of 3 mV (per cell) or greater is
registered over several measured cycles.
This charge output is then switched to trickle charge by the processor to
compensate for loss of charge through for any possible automatic discharge.
The end of charge detection in the case of lead and lead gel batteries on the
other hand occurs via the evaluation of the current/voltage characteristics with
subsequent switching to trickle charge (constant voltage charge with current
limitation).
Each charging channel is provided with a pair of sockets on the front panel of the
unit to connect the battery or battery pack to be charged.
The two sequentially operating charging channels 1 and 2 are designed for a
charging voltage of up to 30 V (corresponding to a nominal battery voltage of 24 V)
and maximum output currents of 3.5 A.
The output current available adjusts itself to the number of cells of the connected
battery.
This means that the output current of remains at 3.5 A up to a nominal battery
voltage of 7.2 V. At 12 V nominal battery voltage, the maximum current is still
2.4 A, but with a 20-cell battery with a nominal voltage of 24 V, maximally 1.2 A
output current is available.
Charge outputs 3 and 4 operate to a maximum of 15 V output voltage,
corresponding to 12 V nominal battery voltage. In this case, the maximum
possible charge current of 1 A is divided to the two simultaneously operating
outputs. If a charge current of 500 mA is programmed for channel 3, for example,
500 mA are also available for channel 4. However, channel 4 can supply 800 mA
if channel 3 only supplies a load of 200 mA.
Near each of the output sockets is an LED which indicates whether the respective
channel is active or not.
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