• Switch mode supply technology - compact, lightweight and efficient
  • Low ripple (<1%) for use with sealed or vented lead acid, VRLA, Planté or NiCd cells
  • 4.5A output rating, switchable for 12/24V and lead acid/NiCd
  • Universal 95 - 277 VAC power supply
  • Open circuit board with optional DIN rail.
Stage V: 
Product Overview: 

The SM135 is a flexible module for use in unattended industrial charging applications. SM135 has a switchable output for use with 12V or 24V lead-acid, or 10 or 20 cell NiCd. Switch-mode power supply technology, with a low ripple DC output, allows the modules to be used with either vented or sealed cells.

The SM135 is a highly efficient performance charger, designed for continuous float charging and standby battery applications. Switch mode technology gives major advances in power supply and battery charger design: compact and lightweight construction, improved efficiency and low heat dissipation, wide supply voltage tolerance and low output ripple. The result is fast, accurate charging, for optimum battery life and reliability.

The wide input voltage range, from 95-277VAC, allows the charger to be used with all common single phase power supplies without adjustment. The very smooth DC output (<1% ripple) makes the SM135 suited for charging sealed VRLA, AGM and Gel batteries, as well as standard vented lead acid and NiCd cells.

The charger uses an open-frame circuit board construction with DIN rail clips, for mounting in an enclosed control panel.

Normal operation
In charge recovery mode, the SM135 gives a constant current output, maximizing the charge recovery rate. As battery voltage approaches the charger’s ‘knee point’ (13 Volts for 12 Volt LA – see graph right), the charger reverts to float charge mode, ramping down output current to maintain optimal cell voltage (without overcharge), while supporting additional battery loads up to the rated maximum current.

Charge current vs voltage
The SM135 can be configured for one of four different charge output voltage settings: circuit board pin header links allow selection of 12V or 24V nominal output voltages, and lead acid or NiCd battery types – see Calibration section.

Boost mode
Boost mode gives an increase in output charge voltage, e.g. for periodic equalizing of charge across cells. To activate boost mode, link the BST terminal to battery negative/ground, ideally using a time relay to limit the boost time period. The boost voltage level is dependent on the selected nominal voltage and battery type – see Calibration section. For each configuration, boost voltage may fine-adjusted if required using one of four potentiometers.

Charge fail output
A charge fail output provides for remote signalling of charger and battery fault conditions.

The output is a solid state transistor rated 200mA, suitable for driving a relay coil, indicating LED (with resistor) or lamp, or control panel annunciator. The output is active (+DC) in normal operation, except momentarily (approx 150milliSec every 2 minutes) when the SM135 switches off the DC output to check battery voltage. The output de-activates during fault conditions, e.g. during AC supply input failure, or if measured battery voltage falls below 66% of nominal.

Output Enable/Inhibit
The SM135 charge output may be remotely enabled or disabled, should this be required for the application. Connect the EN terminal to battery positive to enable the DC charge output, or make EN open-circuit to disable. The charge output also deactivates automatically if measured battery voltage falls below a set level (normally 62% of nominal voltage, adjustable via R42).