Battery Chargers and DC UPS Solutions

Powerbox PB256 Series DC-UPS and Battery Charger

The Powerbox PB256 Series is a 138W DC-UPS and battery charger for critical DC loads in electronic security, access control, telecommunications and water utility installations. A single chassis-mount unit powers the load and charges a sealed lead acid battery, then switches the load to battery without interruption when mains power fails. Two mod...

Two models cover 12V and 24V battery systems. The PB256-1210CML delivers 13.8Vdc at 10A total (8A load, 2A battery by default) and the PB256-2405CML delivers 27.6Vdc at 5A total (4A load, 1A battery). Separate current-limited load and battery terminals mean a heavy load cannot starve the battery of charge, and a flat battery cannot pull current away from connected equipment.

Battery low voltage disconnect prevents deep discharge during extended outages, which is the most common cause of early lead acid battery failure. DC OK and Battery Low alarms are provided as LED indicators and voltage-free changeover relay contacts, ready to wire into security panels, BMS or SCADA monitoring. Natural convection cooling means there is no fan to fail. Order options include conformal coating (-CC) for humid or condensing environments, a temperature probe (-T) and custom charge current (-XX).

The Powerbox PB256 is AS/NZS safety compliant and RCM certified for Australian and New Zealand installations, with local engineering support for selection and integration. For higher power or alternative configurations, compare the full DC-UPS solutions range or browse industrial battery chargers.

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Features

Battery Backup System: ensuring continuous power supply to DC loads during mains powered interruptions.
DC-UPS functionality with seperate current limited battery and load terminals. This ensures both loads and battery are protected.
Trusted in Security Applications: Proven reliability as the backbone for electronic security across Australia, powering critical access control systems and associated security equipment.
Available in 13.8Vdc or 27.6Vdc outputs, suitable for 12V and 24V battery systems, respectively.
Comprehensive Alarms: including DC-OK and Battery Low alarms with LED indicators and voltage-free changeover relay contacts for system monitoring.
Protective Features: Incorporates battery low voltage disconnect, battery overload protection, and optional conformal coating for operation in moist environments.

Specifications

INPUT
Input Voltage	190-.264Vac, or 190-.400Vdc
Frequency	45 to 65 Hz
Input Current	3A maximum
Inrush current	15A on cold start
Line Regulation	0.2% typical

ALARMS AND BATTERY FUNCTIONS
Converter ON/OK alarm	Indicated by voltage-free changeover relay contacts & green LED: ON=OK
Battery low alarm	< 11.3Vdc: 12V Battery < 22.6Vdc: 24V Battery Indicated by voltage-free changeover relay contacts & green LED: ON=OK.
Low voltage disconnect	10.8V (Typical for 12Vdc battery) 21.6V (Typical for 24Vdc battery)
Battery over-load protection	Electronic circuit breaker auto-reset
Battery to load voltage drop	0.2 V (27.6V output)

OUTPUT
Output Voltage	13.8Vdc, 27.6Vdc
Output Power	138W, See power derating curve
Output Current	13.8Vdc: 10A 27.6Vdc: 5A See Selection Table
Load regulation	2% typical
Ripple & Noise	25 mVp-p (13.8Vdc output) 45mVp-p (27.6Vdc output)
Efficiency	> 80%

OPTIONAL FEATURES¹
Battery Charge Limit	Option BCL: Specify battery charge current based on battery size.
Heatsink	Option H: Supplementary heatsink
Conformal Coating	Option CC: Tropic protection for moist areas

PROTECTION
Current limit type (Load circuit)	Constant current > LVD volts Foldback & hiccup < LVD volts
Short circuit protection	Indefinite, auto-resetting
Over-voltage protection	15.5 to 19.5 V latching (13.8Vdc output) 31.5 to 39 V latching (27.6Vdc output)
Reverse polarity protection	Internal fuse
Isolation	Input to Output: 2.1Kvdc 1 min Output to Ground: 2.1Kvdc 1 min Output to Ground: 700Vdc 1 min

STANDARDS AND APPROVALS
C-Tick	AS/NZS CISPR11 Group 1 Class A.
Safety	Complies with AS/NZS 60950, Class 1
EMC	Emissions comply with AS/NZS CISPR11, Group 1, Class B. Complies with ACA EMC Scheme, C-Tick

ENVIRONMENTAL
Operating temperature	0 to 50°C ambient For derating, see curve in technical illustrations
Humidity	5 to 90% relative humidity (non-condensing)
Over-temperature protection	Automatic & auto-resetting
Cooling requirement	Natural convection
Shock/Impact	50G 11mS once each along x, y and z axis

MECHANICAL
Input Connector	AC Mains 10A Class 1 IEC60320 power inlet
Load and Battery Connector	4 way pluggable screw terminal block. Suitable for up to 1.5mm² wire
Alarms Connector	6 way pluggable screw terminal block Suitable for up to 1.5mm² wire
Case size	230 L x 93 W x 46 H (mm)
Weight	850g
Security Cabinet	Option W: WMBB-C-S Wall Mount Box Black with battery Cables and tamper Switch View WMBB-C-S Security Cabinet

Selection Table

MODEL NUMBER	OUTPUT VOLTAGE	LOAD CURRENT	BATTERY CURRENT²	TOTAL CURRENT³	TOTAL OUTPUT POWER
PB256-1210CML	13.8Vdc	8A	2A	10A	138W
PB256-2405CML	27.6Vdc	4A	1A	5A	138W

¹ Example Ordering Code: PB256-1210CML-CC-H4, includes conformal coating, additional heatsink and 4A battery charge current limit

² Other optional BCL, Battery Charging current Limits available on request, factory set.

³ Total output current = sum of load and battery charging current.

Technical Drawings

Technical drawing of a power supply unit with dimensions.

PB256-CML derating curves showing power versus temperature, with and without a heatsink.

Downloads

PB256-Series_DC_UPS_Battery_Charger.pdf

PB256-Operation_Manual_x4.pdf

Warranty & Returns

Warranty periods vary by product. Please refer to the Powerbox Warranty Policy for the applicable coverage period against manufacturing defects from date of purchase. For returns and RMA requests, please visit our RMA support page or contact our support team directly.

FAQs

What is the difference between the 13.8V and 27.6V models?

The 13.8Vdc model (PB256-1210CML) delivers up to 8A to the load and 2A to the battery, making it suitable for 12V battery systems. The 27.6Vdc model (PB256-2405CML) delivers up to 4A to the load and 1A to the battery, designed for 24V battery systems. Both deliver the same 138W total power — select the model that matches your battery and load voltage requirements.

How does the independent current limiting protect my system?

The PB256 uses separate current-limited terminals for the load and battery circuits. This means your connected equipment and your battery are each protected independently — a high-demand load cannot starve the battery of charge, and the battery cannot draw current away from the load. This design prevents both equipment damage and premature battery failure.

What is the Low Voltage Disconnect (LVD) and why does it matter?

The LVD automatically disconnects the battery from the load when the battery voltage drops below a safe threshold during a mains outage. This prevents deep discharge, which is the most common cause of premature lead-acid battery failure. Protecting the battery with LVD significantly extends its service life and reduces replacement costs.

What alarm outputs does the PB256 provide for system monitoring?

The PB256 includes relay alarm outputs for DC Output OK, Battery Fault, and Battery Low conditions, plus corresponding LED indicators on the unit. These alarms can be wired into building management systems, SCADA, or security monitoring platforms to provide real-time fault notification without requiring manual inspection of the unit.

What battery types and sizes are compatible with the PB256?

The PB256 is compatible with standard sealed lead-acid (SLA), AGM, and gel batteries. The battery current is limited to 2A (12V models) or 1A (24V models), so it is best suited to batteries from around 7Ah up to 100Ah. For custom battery charging current requirements, the -XX suffix option allows non-standard charge current configuration — contact Powerbox to discuss your specific battery size.

Is the PB256 suitable for harsh or outdoor environments?

The standard PB256 is designed for indoor chassis mounting. For installations in environments with high humidity, condensation, or exposure to airborne contaminants — such as industrial sites, water treatment facilities, or coastal locations — the optional conformal coating variant (-CC suffix) provides additional protection to the PCB and components. A temperature probe option (-T suffix) is also available for thermal monitoring in high-temperature environments.

What certifications does the PB256 hold for Australian and New Zealand installations?

The PB256 Series meets AS/NZS 60950 safety standards and holds C-Tick EMC certification, making it fully compliant for use in Australian and New Zealand installations. It is suitable for use in regulated industries including electronic security, access control, telecommunications infrastructure, and water utilities.

How do I select the right model number for my application?

Start with your required output voltage — 13.8Vdc for 12V systems or 27.6Vdc for 24V systems. Then confirm your load current requirement does not exceed 8A (12V) or 4A (24V). Add the -CC suffix if conformal coating is needed, -T if a temperature probe is required, or -XX for a custom battery charge current. If you are unsure which configuration suits your application, contact our team at sales@powerbox.com.au for guidance.

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