SIAC M449 External Power Module

© Brooke Clarke 2006

Input End
Output End
Close Up of Input Connectors
Closeup of Output Connectors
Input End J1 (3p IEC AC) J2 (4p DC)
Output End J3 (10s) J4 (4p) J5 (9p)


M449 Series sold by Mil Power Source.

10" long x 5.5" wide x 2" high.  about 3 pounds.

An email from Chuck says:
I was told Sincgars with laptop for fixed field and base use.  It is also a battery charger with auto
switch over from loss of AC to battery and with AC mains working it charges the battery. Well, that is
what I was told.
This would explain the multiple connectors.  I think 4 amps at about 28 volts would be needed to run a SINCGARS (RT-1439) radio in the internal high power mode (not the external Power Amp mode).  This would make a nice base setup.  There's still some questions about what battery can be charged and how it's connected.

An email from Geoff says:
It powered a series of mil computers, based on PC architectures, V2A1, V2A2, GYK-37, etc. in different models.
The DC pin "ins" are in the mil power datasheet attached. It does imply auto crossover from AC to DC backup.


The ID label says:
SIAC/SAIT Electronic Systems, A Division of Science Applications International Corporation
Contract No. DAAB07-91-0-N250
?  5076

The specifications label says:
Input 100-125VAC/200-250VAC
28 VDC Vehicle Power
Output 32VDC @ 4A
CAUTION: HIGH VOLTAGE-No user serviceable parts inside
SHOCK HAZARD, Power Connector is not waterproof
? ...ring wet conditions ....


On one end the AC and DC input connectors

If both vehicle DC and line AC are connected the AC line is automatically used.  If the line fails auto switch over to DC.
J1 - standard IEC line cord jack like used on most test equipment and computers.
Will accept 90 - 264 VAC @ 47 - 440 Hz

J2 - 4 male pin MS3470W14-4P
A & B  = +28 V
C & D = DC return

On the opposite end the DC Output Connectors

Sales Brochure errors and omissions

The M449 Series sales brochure is not clear in the paragraph headed "Selection Guide".  It mentions three outputs as:
#1 = 32V/3.3A,   #2 = 32V @ 1A and #3 = (Battery Charge) @ 700 ma.  But both connectors J3 and J5 have battery charging contacts.
So if no battery charging can the full 4 amps be drawn from J4?  Can the battery being charged also be connected to J2?

Also how to wire the battery and the thermistors for the battery and for ambient?  What battery to use (Lead Acid, Ni-MH, Ni-Cad and what voltage (24?) and AH capacity?  The connector spec in the data sheet for J4 has a type it should be -3S not -33S.

J3 and J5 have the same purpose, to charge a 20 cell Ni-Cad battery.  Note 20 * 1.2 = 24 volts.  Strange they would use a 24 volt battery in a 32 volt power supply.  

J3 - 10 socket MS3470W12-10S

 A & D = +32 vdc
 B & E = +32 vdc return & battery thermistor -
 C = chassis
 F = +5 to ambient thermistor
 G = Battery Charge +
 H = B thermistor +, ambient thermistor -
 I = Battery Return
 K = n.c.
J4 - 3 socket MS3470W8-3S
May be for driving a printer.
J5 - 9 pin M24308/4-1 (DB-9m)
  1.   nc
  2.  Battery discharge +
  3.  nc
  4.  nc
  5. battery thermistor
  6.  battery charge + (power from charger here)
  7.  ambient thermistor
  8. common thermistor
  9. ground

Battery for J5

NSN 6135-01-361-3886
The positive battery terminal is pin 2 and the negative battery terminal is pin 9.  Inside the battery on the pin 9 leg is a thermostat that opens the circuit at 80 deg C and recloses at 55 deg C.  For protection from either high ambient temperatures or from over charging.

The two 10 k Ohm thermistors have a common connection to pin 8 with the ambient thermistor going to pin 7 and the battery thermistor going to pin 5.

Between the battery positive terminal and pin 6 is a thermostat that opens at 3 deg C and recloses at 5 deg C to prevent charging at when it's too cold.

There may be different amp hour capacity batteries which are identified by the resistor between pins 3 and 4 of J5.  I saw this on a block diagram of the battery.  But M449 J5 shows no connection for the power supply, so maybe the resistor is used with different chargers?

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