20/10 Switching Power Supplies with Charger

12/24 VDC Selectable Output

The SPS-20 supervised power supply with battery charger is two high powered, fully isolated, independent power supplies enclosed in one small self contained aluminum package.  Each power supply, outputs 1 and 2, are a nominal 12 VDC at 10As with 12v lead acid battery charger.  These outputs can be used as separate isolated 12 VDC power supplies, or they can be connected in parallel or series to provide 12 VDC, 24 VDC or both 12 VDC and 24 VDC at the same time.  When outputs 1 & 2 are connected in parallel, the output is 13.75 VDC at 20As.  When outputs 1 & 2 are connected in series, the output is 27.5 VDC at 10As.  Because each output is independently regulated, you may draw additional current from the 12V output 1, while using the 24 VDC output at the same time.  The 12v current used has to be subtracted from the 10Amps available on the 24 VDC.  Figures 1 - 4 illustrate each of these four hookups for the SPS-20.

Partial List of Ordering Examples

Part Number Description
PS-1414 (EL) Enclosure - 14" x 14" x 4.75 Power Supply Enclosure
SPS-20EL SPS-20 Power Supply Charger Module Mounted in a PS-1414 (EL) Enclosure
SPS-20ELD4 SPS-20EL with 1 PDM-4-400 with 4, 4A 3AGC fused outputs
SPS-20ELC4 SPS-20EL with 1 PDM-4C-400 with 4, 3.08A PTC Circuit Breaker Outputs
SPS-20ELD8 SPS-20EL with 1 PDM-8-100-400 with 8 4A 3AGC fused outputs
SPS-20ELD16 SPS-20EL with 2 PDM-8-100-200 with 16 2A 3AGC fused outputs
SPS-20ELC16 SPS-20EL with 2 PDM-8C-150-185 with 16 1.5A PTC CIrcuit Breaker Outputs - These output are Class II power limited
-1FT Adding -1FT to a part number adds 1 PDD-FT Fire Trigger transfer to finished part
-1PCI Adding - 1PCI to part number adds 1 PDD-8PCI distribution board with trigger to finished part
-1ACI Adding - 1ACI to part number adds 1 PDD-8ACI Access control interface


  • The SPS-20 has two 12 VDC at 10A (8A Rating) Outputs that can be connected in Parallel or Series to provide 12 VDC, 24 VDC, or 12 VDC & 24 VDC.
  • Outputs 1 and 2 are fully isolated, Independent Power Supplies.
  • Efficient Off-Line Switching Power Supply
  • Self Contained, No External Transformer required
  • 120/240 VAC Operation
  • Extraordinary Brown Out Capability
  • Precise Battery Regulation for Lead Acid Battery(s)
  • LED’s Indicate AC and DC Outputs 1 & 2
  • Relay Contacts Indicates AC Power Status
  • Battery Online, No Drop or Switch Over with AC Power Fail
  • Auto Resetting circuit breaker for Battery(s) Over Current Protection with Reverse battery protection
  • Electronic Power Limited and Short Circuit Protection on each output
  • Each output has Thermal shut down with auto restart


  • AC Input: L, N, G - 3P Terminal block
    • Safety Cover, snap or hinge is provided
    • L= Line, N= Neutral, and G = Ground
    • The G terminal must be connected to Earth Ground.
    • Optional 3 wire line cord P/N:      HA-LC3SZIP
    • AC input/Hz/Watts default      85-133 VAC/47-63Hz/350w
    • Caution: Never apply 240 VAC when SPS-20 is set for 120 VAC this will void warranty and damage unit.
    • AC input/Hz/Watts (set 240)      134-250 VAC/47-63Hz/350w
    • The AC input default is 120 VAC.  You can cut the PCB trace marked “CUT 240” on the bottom of the PCB under the input inductor above and toward the inside of the AC input terminal block.
  • AC LED Indicator (Next to AC Input Terminal Strip)
    • The AC indicator is a bi-color green and red led.  This led off with AC at the terminals would indicate a blown fuse link.  A blown AC fuse link would indicate catastrophic failure and must me returned to the factory for repair.
    • AC Status Output Relay: 3P Terminal block
    • AC fail “C” contacts      2A/120 VAC
    • Three position AC fail terminal block marked “NO, C, NC” are shown in the Normal, energized, AC ON condition.
  • DC OUTPUTS: 4P Terminal block (2 per output)
    • Output-1 & 2      Nominal 12 VDC at 10A each
    • Output-1 & 2 continuous rating 130F     13.75 VDC at 9A each
    • Output 1 & 2 Maximum power           13.65 VDC at 15A each
    • 1A for each output is reserved for battery charging
    • Load regulation no load to max       .25%Typ
    • AC Line regulation 85-136 VAC/170-260 VAC       .03%Typ
    • Each Output ripple & noise at full load       300 mv pp
    • Current Overload Short Circuit Protection        Yes
    • Thermal runaway Protection      Yes
    • Current Overload and Thermal shutdown will auto-restart without removing load.
    • Ambient operating temperature range      -30oF to +130oF
    • Storage Temperature        -60oF to 190oF
    • Switching Frequency        66KHz
  • DC LED Indicators (Adjacent to each output pair)
    • Red
  • Battery Standby
    • Two 12” battery cable assemblies that plug from
    • SPS-20 to battery are provided. Red (+) 12 VDC,
    • Black (–)Neg.
    • Optional 36” battery cable (1) P/N:      WA-36IBAT
    • Battery(s), any type of lead acid      12v 4AH-100AH
    • Battery(s) recharge1 & 2       13.75 VDC at 2A max
    • Battery(s) 1 & 2 PTC self resetting Circuit Breaker      9A
    • Battery)s) 1 & 2 Reverse hookup protection      Yes 
    • In standby mode each battery is limited to 9As of continuous current.  When both outputs are connected in parallel, and standby current will be greater than 9As, you must use 2 batteries connecting one to battery 1 and one to battery 2.  Paralleling (2) battery cables to (1) battery will not double the current.  
    • Review application note 3, Battery Standby table to calculate battery size.
    • To estimate the recharge time in hours for depleted battery(s), multiply the AH rating times 1.2. (AH x 1.2).  As an example, 2 12v 10AH batteries would take about 12 hours to re-charge.
  • Physical
    • SPS-20 Module Dimensions      7.75”L x 4.17”W x 3.23”H 
    • Height includes 7/16” standoffs
    • Mounting Holes Center to Center      6.45”W x 3.41”H
    • SPS-20 module only Weight      2.4lbs
    • SPS-20EL (in Large enclosure)      14” x 14” x 4.75”
    • SPS-20EL Weight with enclosure      11.4lbs
  • Safety
    • %% SPS-20 is UL R/C                               UL603, UL294
    • SPS-20 meets requirements of      UL1950 3rd & EN60950

Do not make series or parallel connections at the batteries, before circuit breaker protection, just at the output as shown above.  Paralleling jumpers in Fig 2 must be 16" of 18 awg wires to add a little resistance so both outputs can share the load.

Specifications are subject to change without notice