VOLTCRAFT ALC 8500-2 Expert User guide
Battery Charging Centre
ALC 8500-2 Expert
Operating Instructions
Contents:
1 Introduction ...................................................................................................................
1.1 The essential performance features of the ALC 8500-2 Expert ....................................
1.2 Proper use .....................................................................................................................
2 Safety Notes
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3 Controls, display elements ............................................................................................ 36
4 Charge processes, charge outputs ...............................................................................
5 Battery capacities, charge power, currents
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6 Battery Ri measurement function .................................................................................
7 Lead-acid activator (reviver) function ............................................................................
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8 Data logger .................................................................................................................... 41
9 USB interface ................................................................................................................
10 The charger in use .........................................................................................................
10.1 Basic settings ................................................................................................................
10.2 Main window .................................................................................................................
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10.3 Channel windows .......................................................................................................... 43
10.4 Channel LEDs ...............................................................................................................
11 Main Menu ....................................................................................................................
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12 Selecting the charge channel, entering data ................................................................. 44
12.1 Channel menu ...............................................................................................................
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12.2 Battery ........................................................................................................................... 44
12.3 Conf. Bat. (configuring batteries) ..................................................................................
12.3.1 Charge rates ..................................................................................................................
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12.4 Function ........................................................................................................................ 47
12.4.1 Charge ...........................................................................................................................
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12.4.2 Discharge ...................................................................................................................... 47
12.4.3 Discharge / Charge .......................................................................................................
12.4.4 Test ................................................................................................................................
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12.4.5 Refresh .......................................................................................................................... 48
12.4.6 Cycle .............................................................................................................................
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12.4.7 Forming (balancing) ....................................................................................................... 48
12.4.8 Maintain
13 B. Resist. (battery Ri measurement function) ................................................................
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14 Conf. menu .................................................................................................................... 51
14.1 Database .......................................................................................................................
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14.1.1 New Bat. ....................................................................................................................... 51
14.1.2 Edit Bat. ........................................................................................................................
14.1.3 Del. Bat. ........................................................................................................................
14.1.4 Return ...........................................................................................................................
14.2 Charge / discharge parameters ....................................................................................
14.3 Setup ALC .....................................................................................................................
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14.3.1 Illuminat. ........................................................................................................................ 53
14.3.2 Contrast ........................................................................................................................
14.3.3 Al. beep .........................................................................................................................
14.3.4 But. beep
....................................................................................................................... 53
15 Display of charged-in / discharged capacity ................................................................
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16 Reading out the data logger on-screen ........................................................................ 54
17 Reading out the data logger via the USB interface
18 Supplementary notes ....................................................................................................
18.1 Reversed polarity protection .........................................................................................
18.2
Discharging single cells .................................................................................................
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18.3 Automatic cooling fan ................................................................................................... 55
18.4 Output stage fuses ........................................................................................................ 55
18.5 Mains fuse ..................................................................................................................... 55
18.6 Temperature sensor ......................................................................................................
18.7 Error messages .............................................................................................................
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19 Maintenance, care ......................................................................................................... 57
20 Specification ................................................................................................................. 58
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1 Introduction
Rechargeable cells, and rechargeable battery packs in particular, are a basic requirement for mobile
equipment, and nowadays they have found their way into virtually all areas of daily life. Today’s consumers expect mobility, especially in the world of communication, and without suitable rechargeable
energy storage devices this would all be unthinkable, as primary cells (dry cells) are too expensive to
be a viable alternative for many applications. Other areas of activity where nothing “works” without
rechargeable battery systems include a vast range of electric tools - and modelling.
Nickel-Cadmium (NC) and Nickel-Metal-Hydride (NiMH) batteries have always played a dominant role
in this field, and they continue to do so, especially where high discharge currents are required. For
these “high-current” applications the strengths of the old, familiar nickel-cadmium battery are just as
important now as they ever were, as their low internal resistance, shallow discharge curve and fast
charge capability are particularly significant.
For a given cell size, Nickel-Metal-Hydride (NiMH) batteries offer considerably higher capacity, and
they are also much more environmentally friendly since they do not contain cadmium, which is a toxic
heavy metal. All the technical parameters of NiMH cells are being improved constantly, and it seems
inevitable that they will increasingly take over from NC cells in the future.
However, the full performance capability of a rechargeable battery, regardless of the cell technology,
is only maintained if the user cares for it in the appropriate way. Overcharging and deep-discharging
have a particularly damaging effect on the useful life of any energy storage device.
Many electrical devices are supplied as standard with chargers which, for obvious reasons of cost,
are devoid of any “intelligence”, and these crude devices do nothing to extend the useful life of the
batteries with which they are used. The modelling world is not immune to this effect, and the useful
life of our battery packs - some of them extremely expensive - is greatly reduced if unsuitable charging
methods are employed. Often this results in a pack which only delivers a fraction of the maximum
possible number of charge / discharge cycles. When you bear these aspects in mind, the cost of a
sophisticated, efficient battery charger is quickly recouped.
1.1 The essential performance features of the ALC 8500-2 Expert
The ALC 8500-2 Expert is an absolute top-notch device in terms of battery charging technology, and
includes performance features offered by no other charger. It provides four charge channels, operating
independently of each other, and capable of carrying out entirely different functions simultaneously. The
charger’s comprehensive range of functions and program sequences are supported by a large, backlit
graphic screen, and the unit is easy to operate thanks to the inclusion of a jog dial and a straightforward
menu system.
The ALC 8500-2 Expert supports all the most important battery technologies, including Nickel-Cadmium
(NC), Nickel-Metal-Hydride (NiMH), Lead-Gel, Lead-Acid, Lithium-Ion (Li-Ion) and Lithium-Polymer (LiPo).
The fir
mware of the forward-looking ALC 8500-2 Expert can be updated at any time due to the use of
flash memory. This means that the software can be expanded and the charger updated to cope with
new or changing battery technologies.
The ALC 8500-2 Expert features four separate charge outputs to which rechargeable cells or batteries
can be connected simultaneously; the generously rated mains power supply allows all four channels to
operate at the same time.
Charge channels 1 and 2 are designed for battery packs containing up to twenty series-wired cells, and
each can deliver a charge current of up to 5 A (according to the cell count; see Table 1). To reduce the
waste heat, secondary pulsed switching regulators are used in this section.
Charge channels 3 and 4 are designed for batteries with a nominal capacity of up to 12 V (10 cells); the
total rated charge current can be divided up over these two channels in any way you wish.
The charger also features a battery database in which you can store charge parameters for individual
batteries; these parameters can then be called up again at any time. When you wish to charge cells or
batteries whose data has already been stored, the charger simply uses that data for its processing,
eliminating the need to set the charge parameters all over again. The ALC 8500-2 Expert also incorporates an integral data logger which records complete charge / discharge cycles without the need to have
Table 1: performance data of the ALC 8500-2 Expert
Nominal battery capacity, channels 1 and 2 ................................................. 200 mAh to 200 Ah
Nominal battery capacity, channels 3 and 4 ................................................... 40 mAh to 200 Ah
Charge power, channels 1 and 2 ........................................................................max. 40 VA total
Discharge power, channels 1 and 2 .......................................................max. 40 VA per channel
Charge power, channels 3 and 4 ........................................................................max. 15 VA total
Discharge power, channels 3 and 4 .......................................................max. 15 VA per channel
Charge voltage, channels 1 and 2 .................. 30 V (max. 24 V nominal voltage with NC, NiMH)
Charge voltage, channels 3 and 4 .................. 15 V (max. 12 V nominal voltage with NC, NiMH)
Charge current, channels 1 and 2 ........................................................................... 40 mA to 5 A
Charge current, channels 3 and 4 ............................................................................. 8 mA to 1 A
Max. dissipated power of heat-sink assembly ....................................................................90 VA
a PC connected all the time. The charger’s USB interface makes it simple to create a PC connection
and transfer data for subsequent further processing.
The USB port can be used to control the charger from a PC, and it also supplies a means of reading out
the integral data logger. The battery data can then be further processed using the associated PC software.
A pack’s voltage level under load conditions is an important criterion when assessing the quality of cells
and batteries. However, if a pack is to maintain a high voltage under load, it is also vital that its internal
resistance should be as low as possible. To determine the internal resistance of batteries the ALC 85002 Expert features an integral battery Ri measurement circuit.
A further special feature of the ALC 8500-2 Expert is its integral lead-acid battery activator (reviver)
function, whose purpose is to prevent crystalline sulphate deposits on the lead plates. Crystalline sulphate deposits are a particular problem with lead-acid batteries which are stored for long periods, are
seldom used, or are only ever discharged at low currents. The useful life of these batteries can be considerably extended by using the activator function.
A summary of the ALC 8500-2 Expert’s most important characteristics and features:
• Four charge channels, for connecting four cells / batteries
• Simultaneous operation on all four channels, even when different functions are selected
• Accurate battery capacity readings; ideal for selecting battery packs
• Charged-in / discharged capacities can be displayed for each battery individually
• Wide range of charge programs for optimum battery care: charge, discharge, discharge /
charge, refresh, cycle, test / capacity measurement, forming (balancing), trickle charge after
main charge
• Support for different battery technologies: NC, NiMH, Lead-Acid, Lead-Gel, Lithium-Ion, Lithium-Ion-Polymer
• Lead-acid activator function for elimination of sulphate deposits
• Integral battery Ri measurement circuit
• Integral data logger for recording and storing complete charge / discharge curve processes
• Data retention if mains supply fails; automatic program start when the mains supply is restored
• USB PC interface for controlling the ALC 8500-2 Expert; also for reading out the data logger
(galvanically isolated)
• Display of cell voltage, charge current, discharge current, charged-in capacity, discharged
capacity
• Integral temperature-controlled cooling fan
• Temperature guard circuits for transformer and output stage
• Future-proof flash technology for firmware updates and upgrades
• Straightforward operation using jog dial and menu control system.
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1.2 Proper use
The charger is designed for charging (fast and normal), discharging and trickle-charging batteries
based on the following technologies: NiCd, NiMH, Lead-Acid, Lead-Gel, Li-Ion and Li-Po. The maximum charge current is 5 A, and the unit can charge batteries with a nominal voltage in the range 1.2
V to 24 V (NC, NiMH). No other type of use is permissible; any other usage invalidates the guarantee
and negates our liability. The same applies to modifications and conversion work carried out on the
unit.
Before you attempt to use the charger for the first time, please read right through these
instructions attentively, paying particular attention to the safety notes.
Do not attempt to charge any type of rechargeable battery apart from the following
types: NiCd, NiMH, Lead-Acid, Lead-Gel, Li-Ion and Li-Po. Never attempt to charge dry
cells with this charger - regardless of type! Dry batteries may explode when charged,
potentially causing severe injury.
Note regarding the charging of Lithium-Ion batteries with integral charge circuits
Many Lithium-Ion batteries, such as the Sony NP 500, the JVC BN-V712U or the Nokia 8110
or 81101, are equipped with integral charge / protective circuitry. The basic rule is that batteries with integral electronics must not be connected to the ALC 8500-2 Expert, as the electronics could be damaged, or the batteries might not be completely charged.
Before you connect a Lithium-Ion battery to the ALC 8500-2 Expert, please check with the
manufacturer that the pack does not include integral charge circuitry or protective electronics.
Always read and observe the instructions for charging provided by the battery manufacturer.
2 Safety Notes
– The ALC 8500-2 Expert is designed to operate on a mains voltage of 220 - 240 V AC, 50 Hz. For
this reason it must be handled with exactly the same amount of care as any other mains-powered
piece of equipment.
– This device must not be allowed to fall into the hands of children. Store and operate it in such a way
that it is always out of the reach of children.
– Keep the charger’s back panel and ventilation slots unobstructed, to ensure that an adequate airflow
can reach the integral cooling fan.
– Select a suitable location for the charger: it should offer good ventilation, be out of direct sunshine,
well away from radiators and other heaters, motors and anything which vibrates. Never subject it
to excessive humidity, dust and heat (e.g. in a closed vehicle). Do not place the charger on a tab-
lecloth, a deep-pile carpeted floor or similar surface, as this could obstruct proper air circulation.
– The device is approved only for use indoors.
– Do not subject the device to temperatures below 0°C or above 45°C.
– Operate the charger only with the case closed.
– The device should only ever be cleaned using a soft dry cloth; if the case is very dirty, it is permis-
sible to moisten the cloth slightly beforehand. Disconnect the charger from the mains supply before
cleaning.
– Take great care to avoid any liquid entering the device. If fluid should find its way into the machine,
disconnect it from the mains supply immediately, and consult our Service Department.
– Don’t leave the packing materials lying around; children could pick them up and play with them,
and this could be harmful, e.g. the plastic bags, plastic film or securing bands.
– If you are not sure about any aspect of the machine, do not use it. Consult our Service Department
for advice.
Caution!
Before connecting any battery to the charger please check the pack for damage and signs of
oxidation, damaged seals and leakage. Don’t attempt to recharge any battery in this condition;
it is best simply to dispose of it in the appropriate manner, as printed in the disposal label on
the pack.
Important: charging multiple batteries simultaneously
The negative terminals of the ALC 8500-2 Expert’s four charge outputs are not interconnected internally, and therefore are not at the same voltage potential. For this reason it is not permissible to
connect batteries to different charge outputs whose negative or positive terminals are connected to
each other externally.
Caution! Observe the battery directive!
Defective or exhausted batteries must not be discarded in the household waste. Take such
packs to your nearest trade battery collection point, or your local toxic waste recycling centre.
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3 Controls, display elements
13114 1516 7126
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1. Multi-function LCD screen
2. Mains switch
3. OK / Menu button
4. Cursor button, fl
5. Cursor button, ‡
6. Battery positive terminal sockets
7. Battery negative terminal sockets
8. Charge output 1
9. Charge output 2
10. Charge output 3
11. Charge output 4
12. Channel LEDs
13. LED lead-acid activator function
14. Power indicator
15. USB interface (back panel)
16. Socket for external temperature sensor (back panel)
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4 Charge processes, charge outputs
During the charge process the micro-controller constantly monitors the course of the voltage at each
charge output individually. A series of successive measured values is used to assess the charge
curve. For best possible results from the charge process the ALC 8500-2 Expert constantly monitors
the charge curve for the appropriate battery type with 14-bit accuracy.
Reliable detection of the optimum charge cut-off point is particularly important. With NC and NiMH batteries the charger employs the reliable method of negative voltage difference (peak cut-off) at the end of the
charge curve. Charge currents greater than 0.5 C are recommended, as they generate a pronounced DeltaV which the charger detects easily. If the unit registers a voltage difference of a few mV in the downward
direction over several measurement cycles at the battery, that channel switches to a trickle charge rate.
The same applies to NiMH batteries, except that the charge curve is shallower than that of NC batteries, and the charger takes this into account. In the case of Lead-acid, Lithium-ion and Lithium-polymer batteries the charge cut-off point is detected according to the current / voltage curve.
Transfer resistances at the terminal clamps can have an adverse effect on the accuracy of the measurement, and for this reason the battery voltage of NC and NiMH batteries is always measured under
zero-current conditions. Batteries which have been stored or deep-discharged tend to provoke premature charge termination, but the ALC 8500-2 Expert features an additional pre-peak detection
circuit which reliably prevents this occurring.
Where batteries are in a deep-discharged state, the ALC 8500-2 Expert delivers an initial pre-charge
at a reduced current.
Most high-capacity nickel-metal-hydride batteries are very sensitive to overcharging, but this drawback
is balanced by their immunity to the memory effect, which is a common problem with NC batteries.
Long intervals between periods of use, followed directly by recharging (i.e. without first discharging)
are one cause of the memory effect with NC cells; another is constant partial discharges followed by
topping-up. The electrolyte then tends to crystallise out at the electrodes, thereby obstructing the flow
of electrons within the cell. A series of discharge / charge cycles often has the effect of restoring the
full capacity of such packs.
Clearly a charger which only provides a simple charge function is not sufficient for optimum maintenance of any rechargeable battery. The ALC 8500-2 Expert offers various programs for comprehensive battery maintenance, all aimed at maximising useful battery life. As you would expect, all channels
can be programmed to carry out different processes at the same time.
To dissipate waste heat during discharge processes the ALC 8500-2 Expert is equipped with an internal heat-sink / cooling fan assembly, and a temperature monitor operates constantly at the output
stages to protect the charger from overloading in every situation.
Charge channels 1 and 2 are designed for a charge voltage up to 30 V (corresponding to a nominal
battery voltage of 24 V with NC and NiMH) and maximum output currents of up to 5 A.
The output currents available vary according to the cell count of the connected battery, as they are
limited by the available charge power.
The maximum total charge power for channels 1 and 2 is 40 VA. Please note that the basis for calculating this figure is not the nominal battery voltage; a higher voltage must be taken into account under
charging conditions. For example, if an output power of 30 VA is drawn for channel 1, the 10 VA is still
available for channel 2. As long as the total power remains below 40 VA, both channels operate simultaneously. If this is not the case, the channel whose process was started last has to wait until the
required power is available, i.e. when the charge process of the channel first started is concluded; the
second process then starts automatically.
Charge outputs 3 and 4 are designed to operate at a maximum output voltage of 15 V, corresponding
to a nominal battery voltage of 12 V with NC and NiMH batteries. In this case the maximum possible
charge current is 1 A, shared by the two outputs working simultaneously. For example, if a charge
current of 500 mA is selected for channel 3, then 500 mA is also available for channel 4. However,
channel 4 can supply 800 mA if channel 3 is only delivering 200 mA.
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The main display window always shows whether a particular channel is actively working, and which
process is being carried out. A channel LED is also located above each pair of output sockets; the
LED glows constantly when its associated channel is working actively. When the process is concluded,
the LED lights up briefly every 1.5 seconds. If the process is terminated in an emergency situation,
the LED flashes at a high rate.
5 Battery capacities, charge power, currents
Charge channels 1 and 2 are designed for use with batteries whose nominal capacity is in the range
200 mAh to 200 Ah, while charge channels 3 and 4 can work with nominal capacities of 40 mAh to
200 Ah. The essential performance data relating to the ALC 8500-2 Expert is summarised in Table 1
(Chapter 1.1), but please note that the specified performance for NC and NiMH batteries is not based
on the nominal battery voltage, but on a cell voltage of 1.5 V. A micro-controller is used to manage
the available power.
All four channels of the ALC 8500-2 Expert are capable of carrying out different processes simultaneously. However, if the required power exceeds the specified performance data of the ALC 8500-2
Expert, then the processing occurs sequentially. The screen then displays the message “waiting for
power”, and the process does not start until another channel has ended its process, and the requisite power is available again.
6 Battery Ri measurement function
When assessing the quality of rechargeable batteries, the pack’s internal resistance is particularly
important in addition to its capacity. High internal resistance has a negative effect especially in highcurrent applications, i.e. the voltage declines at the battery itself, and energy is converted into waste
heat. If the voltage collapses under load conditions the battery appears to be flat, although a useful
quantity of residual energy may still be present.
A battery must be at a defined state of charge if its internal resistance is to be determined, and as a
basic rule the pack should be virtually fully charged before carrying out the measurement. If you wish
to compare different cells it is especially important that they should be at the same initial state of
charge.
If abrupt voltage collapses occur when a battery is being discharged, this is a very clear indication
that there is a variation in capacity of the individual cells, or that one or more cells are already damaged. If a pack in this state continues to be discharged, the result may be polarity reversal and further
damage to the affected cell or cells. In contrast, accurately selected cells always produce highly reliable battery packs which have a particularly long useful life.
For these reasons it is essential to use identical cells when assembling a battery; there should be no
different cells in the pack, and certainly no cells of different capacity. The more accurately you select
the cells, the better the battery pack, and the longer it will last.
It is often impossible to determine the state of ageing batteries accurately simply by measuring their
capacity; checking their internal resistance at a defined state of charge gives a much more accurate
basis for assessment. Internal resistance is certainly the most useful criterion for determining a battery’s
maximum load capacity. Typical values with very high-quality sub-C cells are in the range 4 mOhm to
6 mOhm.
The battery’s internal resistance is responsible for voltage losses in any battery-operated system, but
it is not the only culprit: parasitic transfer resistance, caused by cables and connectors, is always
present. These values can also deteriorate considerably in the course of time through oxidation at
connector contact surfaces or screwed electrical connections, and under heavy current loads this
additional resistance can cause considerable voltage losses at the power supply.
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