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12.4.5 Refresh
The Refresh function of the ALC 8500-2 Expert is primarily intended for use with defective or damaged
batteries, most of which can be re-used after subjecting them to this program. This applies in parti-
cular to deep-discharged batteries, and packs stored for a long time, but also to batteries which ex-
hibit a cell short, all of which are often usable again after this process has been completed.
The program starts by checking whether a voltage is present in the battery or not; it then discharges
it for a while before subjecting it to powerful pulses of current. If you have a battery with a shorted cell,
the "Refresh" function is best carried out at channel 1 or 2, as higher current pulses are available at
these outputs. After this the ALC 8500-2 Expert automatically carries out three charge / discharge
cycles.
The first of these charge cycles is carried out at a current corresponding to 10% of the previously
entered nominal capacity. Since the charge process of a battery previously damaged in this way often
fails to exhibit the typical curve, the Delta-V cut-off point detection is switched off for the first charge
cycle. Since a timer-controlled charge now takes place, it is clearly important that you enter the correct
nominal capacity beforehand.
The two subsequent charge cycles are carried out with the charge / discharge currents corresponding
to 50% of the battery's nominal capacity, with the Delta-V cut-off point detection re-activated.
At the conclusion of the last charge process the battery is fed a trickle current to keep it in the fully
charged state.
12.4.6 Cycle
Batteries which have not been used for a long period are generally incapable of delivering their full
capacity. The primary purpose of the "Cycle" (regeneration) function is to revive batteries in this state.
The program automatically repeats the charge / discharge cycle using the pre-set charge and dischar-
ge currents until it detects no increase in capacity. When the cycle program has finished, the screen
displays the last value for charged-in capacity, and then switches over automatically to a trickle char-
ge which compensates for energy loss through self-discharge.
12.4.7 Forming (balancing)
New batteries are not capable of providing their full performance from the very first charge cycle. For
this reason the ALC 8500-2 Expert can be set to give a new pack a configurable number of initial
charge / discharge cycles in order to bring it up to maximum capacity. The basic rule is that batteries
are formed, or balanced, by charging them at reduced current; the charge rates available are those
shown in Fig. 20. After the second charge process the program switches from the forming current to
the set charge and discharge currents, but with a maximum of 1C.
C/10
12.4.8 Maintain
The "Maintain" function is intended for any battery which is not to be used for a long period, but
whose full performance must be available when required. This function gives NC and NiMH batteries
a full charge, after which a trickle charge is applied to compensate for capacity losses caused by
self-discharging; this is the same process as a normal charge. However, the "Maintain" function au-
tomatically discharges the pack to the final discharge voltage once a week. In the case of lead-acid
batteries 10% of the nominal capacity is removed from it once a week, and then charged back in
again. Used in conjunction with the lead-acid activator function, this program constitutes a highly
efficient means of preventing hardening and passivation of the lead plates. Naturally, the pre-set final
discharge voltage is taken into account during the discharge process.
C/5
C/3
C/2
48
Fig. 20: Selecting the forming
current on the ALC 8500-2
Expert
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