There are two ways that DC power can be supplied to a Squad Radio, either from a special battery that utilizes a male and female snap connector or by means of the AUDIO connector. I recently learned that the Alarm Chemical Agent Automatic AN/PSR-2 uses the same battery. Are there other items that use the same battery? Contact me
PRC-68 Family Battery Portrait - Side by Side images of Top, Front, Bottom all to the same scale.
It's a good idea to remove the battery when not using the radio because it's very easy for the "OFF VOL" control to get turned on and there is no light to tell you this is the case, only the LCD.
Note: there is an insulating sleeve around one of the terminals on both the radio and battery. That way in you attempt to install the battery with the terminals reversed there will be no electrical connection.
Primary - Non Rechargeable
The BA-1588/U Battery, Mercury (probably no longer available). These have a low discharge rate = long shelf life.
Has the PRC-68 frequency chart printed on the side.
Photo with battery case sawed in half.
Secondary - Rechargeable
The BB-588/U Battery, NiCad is a stand alone battery that needs to be used with a battery housing.
There is a screw in on the top, maybe to allow the battery to vent when charging and to be closed during operation?
The battery construction and material is very similar to the BA-5588.
The words on the Front say: BB-588/U, NiCad Sealed, 13.2 V 0.55 AH @ 0.65 A, USN 6140-01-091-1536, DAA 807-90-C C018, Delta Concepts, Farmingdale NY.,,, Charge at a constant current 130 mA for 6 hours. Battery temp should be between 40 F (5 C) and 100 F (38 C) during charge. Enter date of charge on label on top of battery with pencil.
BB-715/U - Terminals (no temperature sensor test point) - overall height 5 1/4" whereas the -2295 is under 4" high.
15.5 BEGIN V.
13.4 WORKING V.
12.0 DISCHARGE V.
NICAD BATT SEALED
MFR.T.D.I. 55150 Thomas & Betts bought T.D.I
(Date Code) 0385
Part No 548103-804 is the battery used on the PRC-128. It is in it's own housing that has recharging sockets on the bottom so that when it is installed in the OF-185 the battery will be charging.
Battery, NiCad 15 Volts 0.80 AH at 0.16 A, NSN 6140-01-241-2295, FO4606-88-D-0019, Saft America, Inc., use only with battery chargers: part no. 706841-801 or part no. 565604-801. Contains 14? each AA size NiCad cells. The male terminal (on bottom in image) is the Positive and the female terminal with the fingers is the negative. The test point is a positive temperature coefficient resistor that is in effect an internal thermometer.
The normal charge rate would be 0.8 A / 20 = 40 mA (Mike Murphy recommends 30 mA & 18 V on a power supply).
17 Volts at full charge.
BB-388 Nickel Metal Hydride
This is the newest in the series with modern chemistry that does not have the memory problem that NiCads have.
See the PRC-68 Family Battery Portrait page for more information on this battery. It has a State Of Charge (SOC) indicator.
Battery BoxThe Battery Box has two spring loaded clasps that hold the box to the radio module housing. The springs should be lubricated with the same Silicon Grease that is used for all the rubber o-rings and gaskets. This makes the latching process go much smoother than with an old rusted catch mechanism.
Maha - MH-C777PLUSThis is a modern microcontroller based commercial Charger/Conditioner that measures Amp Hours as current * time for both charge and discharge. It is rated for up to 14.4 Volt batteries (using 1.2 V/cell * 12 cells). It is powered from a 24 VDC in line power supply or can be powered from an external 24 VDC source. A car cigar adapter cord isincluded, but when this is used the C777 can only charge batteries up to 7.2 Volts (good for RC cars). It includes a temperature probe with a magnet that does stick to the plastic outer wrap of a BB-388.
The LCD display shows the terminal voltage, time in minutes that the charge or discharge has been going and the mA house put in or taken out. Remember that when charging the mA Hours will not be the battery capacity because it will depend on how much charge the battery started with. When discharging the capacity of the battery is measured.
I received a BB-388 that was totally dead and the C777 just beeped and showed error 1 (reverse polarity) in both positions of the polarity switch. I used a power supply to trickle charge the BB-388 at 40 mA for an hour or two and it's terminal voltage came up from 0.6 to about 2.0.
The C777 applies what they call a surface charge for 3 minutes to raise the battery voltage so that it can determine the number of cells. (there is a switch for Nickel or Lithium chemistry). After 3 minutes the terminal voltage was still too low, so back to the 30 mA trickle charge. after s few cycles of trickle - 3 minute surface (fast) charge the terminal voltage was in the 14 Volt area and so I let the charger put in a charge. After a number of hours it showed 2.2 AH had been put in.
After letting the battery cool down, I discharged it and got 1.6 AH capacity. After charging overnight the gas gauge showed 3 out of 5 bars. I am now giving it another discharge in the hope that then next charge will bring the gas gauge to full. (24 June 2001).
After 331 minutes (5 hr, 31 min) the BB-388 was discharged to 8.9 Volts (must be the Maha defination for Nikel chemistry).
The battery provided 1.896 AH of capacity. This was from a 3 bar fuel guage starting point.
Next recharge and see how many bars on the battery.
After 166 minutes the charger stopped with a terminal voltage of 13.9 Volts and it put in 1.921 AH, BUTonly 1 bar on gas guage? . . . now try discharge. and a 40 mA trickle charge for 3 days . . . 27 June 2001 - 3 bars showing on gas guage.
Note that Maha makes a NiMH AA cell rated for 1.7 AH. 10 of these will provide more than twice the capacity of the now current NiCad battery packs being sold as surplus.
At home I am using a B & K Precision model 1786 power supply set for 18.0 Volts and 0.04 Amps. When fully charged the voltage reads 17.x volts.
For traveling I built a Simple battery Charger for NiCad BB-588 or equivalent.
PP-7601/U Charger, BatteryeBay Photo - 6 station suitcase type unit. NSN 4G 6130-01-080-657, made by Fourdee 07661,
CAGE 07661 is now listed as: Systems and Electronics Inc (SEI), 2001 E Lake Mary blvd
Sanford, FL 32773-7140
PP-8444A/U Portable Charger - PP-8444/U (eBay) - Power Sources Newsletter - Fifth Edition April 1999 -
706841-801 & -802
There is a reverse polarity protection diode in series with AUDIO J5-E as well as a diode in series with the battery positive terminal on the PRC-68B and newer Squad Radios. The common cathodes of these go to the ON-OFF switch so that whichever has the higher voltage will power the radio. The PRC-68 and PRC-68A accept external power when the PWR switch is in the OFF position. There does not appear to be a provision to charge the battery since primary as well as rechargeable batteries may be used. AUDIO J5-A is the ground connection.
Note: The external DC power supply should be in the 11
to 16 VDC range. The Audio/Power
Test Adapter has a 16 V Zeener diode and 0.6 A fuse to
protect the radio from over voltage.
If the external DC power supply gets as low as about 10 V the battery warning beep will start on the PRC-68A and newer Squad Radios.
Page Created 15 April 2001.