Guardian Series UL Approved Battery Chargers
Guardian Series UL Approved Battery Chargers


  • Heavy duty float charging: 10A @ 12/24 VDC or 20A @ 24 VDC
  • Auto boost operation
  • Temperature compensation
  • NFPA 110 alarm outputs: charge fail, under volts & over volts
  • High quality stainless steel case, suitable for wall mounting


The Guardian is a high efficient, high performance battery charger. The output is configured for accurate fast charging, optimum battery life and reliability. High impedance transformer technology gives a low ripple output (<1%) for optimal charging of vented or sealed lead acid or NiCd batteries. The enclosed Guardian range can be used in a wide range of industrial charging applications, including standby engines, pumps and generators.


Each charger consists of transformer, rectifier and control circuit in a metal wall-mounted enclosure with DC ammeter and voltmeter. The control circuit ensures that the charger maintains the battery voltage at the pre-calibrated float level, while supplying any additional load current up to the specified maximum.



Auto boost operation provides a temporary increase in output voltage, equalizing the battery charge between cells and maximizing battery life and capacity. Auto boost is triggered automatically when the battery falls below a preset voltage, and can also be triggered manually by linking two ‘boost’ terminals, e.g. using a panel switch or push-button. Once the batteries have reached the boost voltage level, Guardian reverts to its normal float charge mode, preventing battery over-charge and gassing.



Guardian chargers can be configured (using circuit board links) to give automatic compensation of output voltage with varying temperature, ensuring optimal charging and cell life. Temperature is measured by a circuit board mounted sensor, or RTC option remote sensor complete with 9.5 ft (3m) lead assembly. When temperature compensation is enabled, output voltage decreases as ambient temperature increases at a rate of 1.66mV per °F per cell (3mV per °C per cell) –. see Output Calibration section.



The Guardian provides 3 x NFPA110 compliant alarm relay outputs: battery low volts and battery high volts (both with 120 sec delay) and charge fail. 



Wall or surface-mounting is via slots/holes in the stainless steel case. Connection to the wiring harness is by spring clamp terminals, through access holes in the case side. AC supply input and DC charge output are protected with circuit-board mounted fusing. Please see installation and operation instructions for full details. 

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