Battery Chargers
Powerbox PB251A-RM SERIES DC-UPS / Battery Charger - 19" Rack Mount
The Powerbox PB251A-RM Series DC-UPS and Battery Charger is a robust 19" rack-mountable power solution, delivering 220-330W of reliable DC power and intelligent battery management. Designed for critical applications, it is ideal for telecommunications, industrial systems, and backup power solutions.
Read More
Features
- Trusted in Critical Applications: Widely deployed in radio communications, nurse call systems, and security/access control infrastructure, the PB251A-RM provides dependable backup DC power for mission-critical systems where continuity is essential.
- True Off-Line DC-UPS Functionality: Seamlessly delivers power to connected loads from the AC mains during normal operation and automatically switches to battery backup during outages—ensuring uninterrupted operation without dips or reset events.
- Compact Rack Mount Design: Housed in a 2RU 19" rack-mount enclosure, with models delivering up to 330W of output power at 13.8Vdc or 27.6Vdc, this unit fits easily into communication racks, control rooms, and centralised power cabinets.
- Comprehensive Battery Management: Includes built-in battery low-voltage disconnect (LVD), constant float voltage, current limiting, and auto-resetting circuit protection. A digital display and alarm relays provide real-time system status and fault indication.
- Various Options Available: Including SNMP V1 network interface for remote monitoring, analogue meters, temperature compensation, and factory-set battery charge current limits tailored to battery specifications.
- Designed and Manufactured in Australia: Proudly engineered and built by Powerbox in Australia, the PB251A-RM reflects decades of local expertise and compliance with Australian standards for safety, EMC, and industrial performance.
Specifications
Selection Table
Technical Illustrations
Downloads
| INPUT | |
|---|---|
| Input Voltage: | 190...264Vac, or 225...400Vdc |
| Frequency | 45 to 65 Hz |
| Input Current: | 1.4A maximum |
| Inrush current: | 10A maximum |
| Line regulation: | 0.2%typical |
| ALARMS & BATTERY FUNCTIONS | |
|---|---|
| DC Ok alarm | Green LED : ON=OK voltage free change over relay contacts (32V,1A) Alarms on loss of AC mains power or failure of off-line AC/DC converter / battery charger |
| Charger voltage OK alarm | Green LED : ON=OK voltage free change over relay contacts (32V,1A) Alarms on battery low voltage, failure of battery fuse or battery disconnected. Alarm cancelled when fuse or battery replaced, or AC input restored |
| Battery low voltage disconnect(LVD) | Low voltage disconnect 10.5V for 12V battery, 21V for 24V battery, adjustable 1.6 to 2.0V / cell all models |
| Charger over-load protection | Auto-resetting electronic circuit breaker |
| Reverse polarity protection | Internal battery fuse |
| Battery to load voltage drop | 0.2 to 0.35V typical model dependant |
| OUTPUT | |
|---|---|
| Output Voltage | 13.8Vdc, 27.6Vdc |
| Output Power | 275W - 330W |
| Output Current | 13.8Vdc: 20A 27.6Vdc: 12A |
| Load regulation | 0.5% typical |
| Ripple & noise | 100 MHz bandwidth 28mVp-p (13.8Vdc output) 55mVp-p (27.6Vdc output) |
| Efficiency | > 80% |
| OPTIONAL FEATURES² | |
|---|---|
| Battery Charge Current | Factory set to any value within adjustment the range. For the PB251A-12RML, battery charging current limit can be set from 2A to 20.5A . For the PB251A-24RML battery charging current limit can be set from 1A to 12.5A . Battery charging current option can be specified when ordering e.g. PB251A-12RML-10 for 10A setting. |
| Network enabled | Option N: Internal network card in conjunction with PB251A becomes a network enabled device combining the benefits of SNMP V1, XML and embedded webpage. |
| Analogue meters | Option M: Load voltage, load current, battery charge and discharge. |
| Temperature compensation | Option T: 2.5m cable probe Option T5: 5m cable probe Float voltage set to 2.3V/cell at 25°C with compensation of 3.3mv/°C cell |
| Battery Capacity Test | Contact Powerbox for further information |
| ENVIRONMENT | |
|---|---|
| Operating temperature | 0 to 70°C ambient Derating from 40°C at 2.5%/°C |
| Humidity | 5 to 90% relative humidity (non-condensing) |
| Over-temperature protection | Automatic & auto-resetting |
| Cooling requirement | Natural convection |
| MECHANICAL | |
|---|---|
| Input connector | IEC60320 inlet,10A Class 1 2 meter IEC mains cord with Australian plug is supplied with each unit |
| Output and battery connector | PB251A-RML: M4 screw terminals |
| Alarm terminal | PB251A-RML: M3.5 screw terminals |
| Enclosure | 19" Rack Mount, 2RU height, 232mm Mounting slots suitable for M6 hardware |
| Weight | 5.5kg |
| STANDARDS | |
|---|---|
| C-Tick | AS/NZS CISPR11 Group 1 Class A. |
| Safety | Complies with AS/NZS 60950, class 1, NSW Office of Fair Trading Approval N20602 |
| EMC | Emissions comply with AS/NZS CISPR11, Group 1, Class B. Complies with ACA EMC Scheme, Safety & EMC Regulatory Compliance Marked |
| MODEL NUMBER | OUTPUT VOLTAGE | LOAD CURRENT |
BATTERY CURRENT LIMIT (BCL)¹ |
TOTAL CURRENT | OUTPUT POWER | MECHANICAL |
|---|---|---|---|---|---|---|
| PB251A-12RML | 13.8V | 16A | 4A | 20A | 275W | 19" Rack Mount |
| PB251A-24RML | 27.6V | 10A | 2A | 12A | 330W | 19" Rack Mount |
Notes:
¹ Other BCL option, Battery Charging Limits, available on request. (factory set)
² Example models number, PB251A-12RML-M-10, Includes analogue meters and 10A battery charge current.
| INPUT | |
|---|---|
| Input Voltage: | 190...264Vac, or 225...400Vdc |
| Frequency | 45 to 65 Hz |
| Input Current: | 1.4A maximum |
| Inrush current: | 10A maximum |
| Line regulation: | 0.2%typical |
| ALARMS & BATTERY FUNCTIONS | |
|---|---|
| DC Ok alarm | Green LED : ON=OK voltage free change over relay contacts (32V,1A) Alarms on loss of AC mains power or failure of off-line AC/DC converter / battery charger |
| Charger voltage OK alarm | Green LED : ON=OK voltage free change over relay contacts (32V,1A) Alarms on battery low voltage, failure of battery fuse or battery disconnected. Alarm cancelled when fuse or battery replaced, or AC input restored |
| Battery low voltage disconnect(LVD) | Low voltage disconnect 10.5V for 12V battery, 21V for 24V battery, adjustable 1.6 to 2.0V / cell all models |
| Charger over-load protection | Auto-resetting electronic circuit breaker |
| Reverse polarity protection | Internal battery fuse |
| Battery to load voltage drop | 0.2 to 0.35V typical model dependant |
| OUTPUT | |
|---|---|
| Output Voltage | 13.8Vdc, 27.6Vdc |
| Output Power | 275W - 330W |
| Output Current | 13.8Vdc: 20A 27.6Vdc: 12A |
| Load regulation | 0.5% typical |
| Ripple & noise | 100 MHz bandwidth 28mVp-p (13.8Vdc output) 55mVp-p (27.6Vdc output) |
| Efficiency | > 80% |
| OPTIONAL FEATURES² | |
|---|---|
| Battery Charge Current | Factory set to any value within adjustment the range. For the PB251A-12RML, battery charging current limit can be set from 2A to 20.5A . For the PB251A-24RML battery charging current limit can be set from 1A to 12.5A . Battery charging current option can be specified when ordering e.g. PB251A-12RML-10 for 10A setting. |
| Network enabled | Option N: Internal network card in conjunction with PB251A becomes a network enabled device combining the benefits of SNMP V1, XML and embedded webpage. |
| Analogue meters | Option M: Load voltage, load current, battery charge and discharge. |
| Temperature compensation | Option T: 2.5m cable probe Option T5: 5m cable probe Float voltage set to 2.3V/cell at 25°C with compensation of 3.3mv/°C cell |
| Battery Capacity Test | Contact Powerbox for further information |
| ENVIRONMENT | |
|---|---|
| Operating temperature | 0 to 70°C ambient Derating from 40°C at 2.5%/°C |
| Humidity | 5 to 90% relative humidity (non-condensing) |
| Over-temperature protection | Automatic & auto-resetting |
| Cooling requirement | Natural convection |
| MECHANICAL | |
|---|---|
| Input connector | IEC60320 inlet,10A Class 1 2 meter IEC mains cord with Australian plug is supplied with each unit |
| Output and battery connector | PB251A-RML: M4 screw terminals |
| Alarm terminal | PB251A-RML: M3.5 screw terminals |
| Enclosure | 19" Rack Mount, 2RU height, 232mm Mounting slots suitable for M6 hardware |
| Weight | 5.5kg |
| STANDARDS | |
|---|---|
| C-Tick | AS/NZS CISPR11 Group 1 Class A. |
| Safety | Complies with AS/NZS 60950, class 1, NSW Office of Fair Trading Approval N20602 |
| EMC | Emissions comply with AS/NZS CISPR11, Group 1, Class B. Complies with ACA EMC Scheme, Safety & EMC Regulatory Compliance Marked |
| MODEL NUMBER | OUTPUT VOLTAGE | LOAD CURRENT |
BATTERY CURRENT LIMIT (BCL)¹ |
TOTAL CURRENT | OUTPUT POWER | MECHANICAL |
|---|---|---|---|---|---|---|
| PB251A-12RML | 13.8V | 16A | 4A | 20A | 275W | 19" Rack Mount |
| PB251A-24RML | 27.6V | 10A | 2A | 12A | 330W | 19" Rack Mount |
Notes:
¹ Other BCL option, Battery Charging Limits, available on request. (factory set)
² Example models number, PB251A-12RML-M-10, Includes analogue meters and 10A battery charge current.
Find the Right Model
| Model Number | Input Voltage (Vac) | Output Voltage (Vdc) | Output Current (A) | ||
|---|---|---|---|---|---|
|
PB251A-12RML | 190...264Vac 50/60Hz | 13.8Vdc | 20A (Default = 16A Load / 4A Battery) | |
|
|
PB251A-24RML | 190...264Vac 50/60Hz | 27.6Vdc | 12A (Default = 10A Load / 2A Battery) |
Need help finding the right product model?
