Squad Radio DC Power

Brooke Clarke 2001 - 2015


Batteries
Chargers  Maha,
External Power
Links
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.

Batteries

CAUTION

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

Secondary - Rechargeable

Battery Box

The 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.

Chargers

Maha - MH-C777PLUS

This 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.

Power Supply

Home Made

PP-7601/U Charger, Battery

eBay 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

706841-801 & -802

External Power

Links

Back to Brooke's Military Audio, PRC68.com, Squad RadioMilitary Information, Home page

Page Created 15 April 2001.