PP-8444A/U Universal Portable Charger (UPC)
NSN 6130-01-443-0970

©Brooke Clarke, N6GCE



P-8444 Battery Charger


Description

This is a field portable battery charger made by Bren-Tronics.  It can be powered by either 100 to 250 VAC 50/60 Hz @ < 2 amps (or from 24 VDC @ < 8 amps using a special cable that's not attached to the charger.  An adapter is needed for each battery type to be charged.  The UPC charges the NiMH and NiCAD batteries fully in two hours.

Batteries Supported

Model
 Chemistry
BB-390A
 Ni-MH
BB-388
 Ni-MH
BB-516A
 Ni-Cad
BB-503A
 Ni-Cad
BB-2847
 Li-Ion
The BB-2590 is NOT supported.  See the newest SPC PP-8498 for that, or other military battery chargers.

Versions

Model
 NSN
 Description
PP-8444
 6130-01-427-9604
5940-01-467-1176
 90 - 125 VAC
PP-8444A
 6130-01-443-0970
 100 - 250 VAC

Operation

After installing one or two BB-390 batteries and turning on either the AC or DC input the charger will check the battery temperature by measuring the resistance between battery pin 6 and the two "tabs" on top of the BB-390, if the battery is not hot and the voltage of each side is 10 or more the charger applies 4 amps to one side of the battry and every now and then (you can hear the relays clicking) alternately charges the a and b sides.  If the temperature gets up to 55 deg C (+/- 5) the charging current drops back to a 100 ma trickle charge.  If less than 10 Volts then there'a pause and voltage check to be sure pack voltage is increasing (if it's not then there's probably a bad cell and the battery should not be charged).

I think the thermistors in the BB-390 are rated at 10 k Ohms at 25 deg C.  This is a very common type.

Note that the BB-390 is a Ni-MH chemistry that gets very hot at the end of charge and the PP-8444 uses this heating as an end of charge indicator.  But to get full charge into a Ni-MH cell a topping off or trickle type charge is needed.

It's not clear how the Green LED is activated to say the battery is fully charged.

The PP-8444 with the BB-390 adapter will NOT charge a BB-590 or my 5590BA since neither of these has the two electrical top contacts.

This charger did not work when a BB-390 was installed, so I got another one (18 May 2005).  When a BB-390 is installed the green trickle lamp comes on after awhile.  If the battery is removed the green lamp stays lit.

If the 5590BA or a BB-590 is installed it will be charged.  But if the BB-5590 has a terminal voltage of about 6 volts on each battery (about 12 Volts total) the yellow lamps keep flashing and the charger does not try to charge it.  I'm using a lab power supply set for 30 volts and 100 ma to bring the state of charge in the BB-590 up to about 27 volts total and will try it again.  Now after about 4 blinks the yellow light stays lit and it's charging.  I hope it does not explode like the last one.

Battery Adapters

. 
    Fig 1 Top            Fig 2 Bottom
An adapter is used to connect the batteries to be charged to the PP-8444A/U.  There are different adapters for different rechargeable batteries.  The adapter has a Cinch Jones 18 pin plug that mates with the charger and has receptacles on top to hold two batteries.
 
 
Battery
mil p/n
NSN
mfg p/n
Battery Side A
Battery Side B
Battery Center
BB-388/U
AP-388
(J-6357/P)
 5940-01-427-8601
BTA-70288


BB-390A/U
AP-390
(J-6358/P)
 5940-01-427-9110
BTA-70290
1,3- & 4+
2- & 5+
thermistor
BB-503A/U
AP-503
(J-6355/P)
 5940-01-427-9247
BTA-70394


BB-516A/U
AP-516
(J-6356/P)
 5940-01-427-9183
BTA-70395


BB-2847/U
AP-2847
(J-6354/P)
 5940-01-427-9278
BTA-70396


?

BTA-70342


SINCGARS?

BTA-70412


Home Made Battery Adapter

A Cinch Jones P-318-CCT 18 contact plug is needed to mate with the socket on the PP-8444A/U charger.
In Fig 1 Top - the upper battery is "A" and the lower battery is "B".
In Fig 2 Bottom -  the upper right connector pin is #1, the bottom right pin is #3, the upper left pin is #16 and the bottom left pin is #18.

Note that the PP-8444()/U can charge two batteries that Bren-tronics calls Battery A and Battery B.  The BB-390/U battery is really two separate batteries with side a and side b.  Keep this use of A and B in mind when reading the table below where I have used lower case letters for the sides and upper case for the batteries.
 
I/O Pin #
Pin Function**
I/O Pin #*
Battery term
1
 B1 control
relay coil
on = a side batt
#4 2k1 1.1v
#13 2k1 1.1v
#15 1k1 .75v
#16 2k1 1.1v
  
2
 B thermistor
nc
  
3
 B charge Com +
nc
A4 & A5
4
 B2 control
relay coil
on = b side batt
#13 2k1 1.1v
#15 1k1 .77v
#16 2k2 1.1v
1k9 to
A6 & B6
5
 B Charge to
battery
nc
  
6
 Relay +24 VDC
#9 4k6 1.9v
#12 9k3 2.5v
A6 & B6
4k6 -1.9v
7
 nc
nc
  
8
 nc
nc
  
9
 R2 (full voltage)
#12 4k6 1.9v
A6 & B6
10
 nc
nc
  
11
 nc
nc
  
12
 thermistor
DC pwr
nc
4k6 -1.9v to
A6 &B6
13
 A2 control
relay coil
on = a side batt
#15 1k0 .74v
#16 2k2 1.1v
  
14
 A charge current
to battery
nc
  
15
 R1 pack voltage
#16 1k1 .50v
  
16
 A1 control
relay coil
on = b side batt
nc
  
17
 A thermistor
nc
  
18
 A charge Com +
nc
B4 & B5

* Ohm meter test of BTA-70290
* *Based on documents by Trevor Barron.  My pin numbers are based on those that are part of a Cinch Jones plug.  My #1 is his #18, my 3 is his 6, my 16 is his 13 and my 18 is his 1.  With my pin numbers you can see that the functions are grouped in a logical way.  Neither the commercial manual for the BTC-UN108 nor TM 11-6130-489-13&P has any more info.  The only diagram in either manual is a block diagram where the interconnecting wires are not labeled by function, only numbered.

DC Power Cord

The socket for the 24 VDC power cord is a standard IEC line cord socket.  Note that the AC line cord is permanently attached so this is the only socket for supplying 24 VDC only.
 
 
Source
Bren-tronics p/n
mil p/n
NSN
NATO Slave Plug
Hummer
BTA-70413
J-6362/U
5940-01-427-9395
Clips
BTA-70431-1
    
NATO Plug
BTA-70431-2
    

J-6362J-6362 NATO DC Power Cord

Marked: Cable Assembly
24V DC Operation
J-6362/V
NSN  5940-01-427-9395
p/n BTA-70413
DAAB07-01-D-A504
Has a 32 A fuse as part of the salve plug connector (small gray circle in photo).  The slave plug has a single male pin that's about 5/8" OD and the contact fingers have an ID of about 1 5/8".

Manuals

TM 11-6130-489-13&P, Battery Charger PP-8444/U, 1 September 1997
Operation and Service Manual, Universal Portable Battery Charger BTC-UN108 (Commercial version of the PP-8884/U)
Both are available from Bren-Tronics who makes the charger and has very good customer support.

On page 2-8 of the Technical Manual there is a graph showing that after 3 months 80% of the capacity of a NiCad or NMH battery has been lost due to self discharge, but for a Li-Ion battery it takes a year for the same 80% loss of capacity.

DOA

The following troubleshooting was done 22 Nov. 2002 without any documentation on the charger just by observation and some Ohm meter and diode tests (Fluke 87 DMM) plus desoldering  a few components to separate component problems.
Note: I got the manual after completing the troubleshooting but, according to the TM trouble shooting guide I should replace the power supply brick.  The manual seems to be wrong.
When the AC power switch is turned on the LEDs flash, but the fan  and Red POWER ON light do not come on.
Removing the 4 screws on the bottom of the case allows removal of the charger from it's case.
It smells like something has overheated.
Removing 8 black screws around the edge of the panel allows the panel to be folded forward 180 degrees.
The main components of the PP-8444A/U are: When the AC is turned on the 24 VDC goes to zero.  If the red wires going to both Charger PCBs are removed then the fan turns and the POWER ON light comes on indicating a problem with both charging boards.

The Charger PCBs have three connections to the rest of the PP-8444A/U:


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page created 13 June 2002.