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GCDT250A12V is microprocessor device for charging, maintenance and testing lead-acid 12V batteries. It is developed as a consequence of need for small, easy for use, safe, reliable and relatively cheep device for servicing and maintenance of starter batteries. GCDT is transformer-diode charger with resistance for testing the start capability. Charge regime is automatically selected depending on level of emptiness of battery or on conditions in main supply. Charging is realized by combining 4 phases (2 phases of intensive charge, recharge phase, “maintenance” phase), voltage, current, duration and capacity are controlled and many precaution measures are implemented.

Device is microprocessor, with measuring current, voltage, temperature of heat sink of rectifier diodes and energy transformer, so it is possible to implement different algorithms. It is possible to change voltage and current limits, conditioning of charge characteristic, pausing, waiting for event (measuring Ah during charge), conditioning end of charging, connection with PC computer, analyze and printing charge and discharge graphs etc.

Thanks to voltage limit, it is possible to charge without surveillance, because there is not over charge (over night or during weekend). As well, in a case of main power failure during charge, after it’s returning device automatically continues charging with parameters which were previously set (before power failure). Discharging is dissipative with indication of current, voltage, elapsed time and dissipated capacity. LCD display with 2x16 characters shows values of current, voltage, time, capacity, warnings, wrong actions etc. Device is placed in red plasticified steel box with PVC distancers and handle. Main switch, start (scroll) and stop (select) buttons, switches C/D (Charge/Discharge) and R/S (Ready/Set), led diodes, LCD display for indication and connector for communication with PC computer are placed on the devices front panel. Charge and discharge cables and connectors (de montage), power supply cable, automatic fuse in DC circuit of charger, fuse in AC circuit and holders for cables are on the back panel of device.

With software GCDTS v1.01 it is possible to connect device with PC computer via RS232 serial port. Software gives opportunity of showing charge and discharge graphs in real time, possibility of reading charge and discharge data in case that device wasn’t connected with PC, printing and storing the results, creating reports etc.

Discharge resistor value is chosen in a way to achieve 250A from battery when voltage on it’s ends is 10V (0.04R). LCD display and sound signalization help discharge operation by stopwatch and beeping each 5 sec, as well as by freezing last discharge values (at the end of discharge test). After finishing discharge operation, user could read on LCD display complete memorized results of discharge test (values of voltage, current, capacity for each second during test).

Graphical Charging Algorithm over different phases describes capabillity of GCDT250A12V.

Gaus Charge-Discharge Tester GCDT250A12V has following protections:

  1. No sparks during connecting or disconnecting plugs from battery in charge operation
  2. Forced air cooling
  3. Control of a minimum of allowed connected battery voltage (forbidden start for voltages less than 2V)
  4. Temperature protection on heat-sink of semiconductor energy components
  5. Temperature protection of energy transformer (bad conditions in main supply)
  6. In case of main power failure, after its restoring, charging automatically continues with earlier set parameters
  7. Slow fuse 4A 20mm in AC circuit
  8. Automatic slow fuse 40A in DC circuit
  9. Soft start circuit for energy transformer
  10. Impossible start of charge and discharge simultaneously
  11. Short circuit protection (if detected current is more than 30A charger is automatically turned off)
  12. Over voltage protection
  13. Protection from plugs (cables) falling during charge (freezing device until solving of problem)

Please note:

Be careful about polarity of plugs in charge! In case of mistake, the only protection is automatic fuse 40A, so there is a risk of permanent damage.


  • Type of voltage converter: transformer-diode charger, resistance discharger
  • Supply 230V +/- 10%, 50Hz 450W;
  • Nominal input current: 2,5A
  • Maximal start current: 3,5A
  • Instruments: LCD display 2x16 characters, ampermeter 0-40,00A, voltmeter 0-20,00V, stopwatch 0-99sec, temp1 –99 do 99C, temp2 –99 do 99C
  • Nominal charge current 22A (electronic control system permits current between 25A i 30A for a max. of 5 minutes)
  • Charge voltage: 17,2V (phase of intensive charge, choice from 14.4 to 18V), 16V (“maintenance”)
  • Number of combinations of transformer windings in primer: 4
  • Minimal charge voltage 2V;
  • Dimensions (WxDxH): 245x460x160mm;
  • Weight: 16kg;
  • Cables with Pb plugs: l=1,5m, S=6/16mm2
  • Ambient temperature: 0 do +40C

Please note:

Easy changing of charging parameters and algorithm, possibility of communication with PC computer…

Current range 0-24A
Voltage range 2-18V
Output voltage 18V max, for Ca-Ca batt. 17.2V, 16V for Sb lead batt. 16.2V, 15.2V
Output power 370W
Main supply Monophase 50/60Hz, 450W, 230VAC +/-10%
Capacity Charging one 12V battery or six 2V cells inline
Resolution 100mA and 25mV
Accuracy Better then 10%
Energetics gretz diodes
Overrange current protection 30A (immediate disconnection of energetic)
Overrange voltage protection 19V (customized range from user menu)
Efficience ratio 75%
Cooling Forced air cooling
Control characteristics Charger with voltage and current limits
Controled variables Current, voltage, capacity Ah, time
LCD display information State, current, voltage, charging phase, Ah, time …

Discharge current 250A when voltage on resistor is 10V, test duration up to 20sec with compulsive pause (min. 300 sec) for succession discharge tests
LCD dispaly and sound informations Discharge time (0.1 sec resolution), csound beeper every 5sec, last meassured values freezing, current, voltage, capacity

Display 2x16 characters LCD display
Control elements Main switch, start (select) and stop (scroll) tasters, switches C/D and R/S, LED diodes, RS-232 Communication
Case Steel box with red ductile envelope
Dimensions (WxLxH) 245x460x160mm
Weight 16kg
tel / fax: (+381) 11 2279142, (+381) 63 215722, service: (+381) 25 421095