68BA Battery Adapter for PRC-68 Family Radios

Brooke Clarke, N6GCE 2000 - 2007
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Ver 6c

Ver 6c on
                    radio
Radio shown for illustration,
not included with adapter

Corners Marked
                for PSR-2
Two lower corners marked for PSR-2

Description

The 68BA Battery Adapter will power all the radios in the PRC-68 family: PRC-68, PRC-68A, PRC-68B, PRC-126, PRC-128, PRC-136, and other equipment like the Magnavox Stealthcomm, the PSR-2 Chemical Alarm, the BER tester F91100.and the M23  Mortar Ballistic Computer.  The 68BA directly replaces the BA-1588/U, BA-5588/U, BB-588/U, BB-388/U and with the use of your battery box will replace the BB-715/U, 548103-804, 6140-01-241-2295.  Note that the talk time is a strong function of the type and number of batteries you use. The M23 Mortar Ballistic Computer will run for about 10 hours using 10 each Alkaline AA cells.
68BA SetThis adapter comes with a printed circuit board that has snaps to hold either:
2 each 9 Volt batteries
4 each 9 Volt batteries
1 each battery holder that has 10 each AA batteries
1 battery holder for 2 ea. AA batteries with a gimmick to electrically insert them in series with the 10 AA batt.
4 screws to mount the PCB to a PRC-68 family radio
4 foam packing strips to fill up the space in the battery box
A small modification of the printed circuit board needs to be done by the user to fit the PSR-2 battery compartment.  The latest version has the radius lines marked for easy filing of the corners needed.

Batteries not included.

2016 Instruction Sheet.pdf - note the 2AA battery holder is no longer included (I never used it).

2000 Instruction Sheet.pdf

Features

Can use 9 volt or AA batteries

The batteries can be primary or rechargeable.
 
10 each AA
12 each AA
2 each 9 Volt
2 each 9 Volt
4 each 9 Volt
10 AA
12 AA
2 x 9V
                    Left
2 x 9V
                    Right
4 x 9V

Safety Insulating Sleeve on Negative Terminal

There is an insulating sleeve around the negative terminal to prevent connecting two batteries in a way that would cause a short.  This insulator also prevents touching the radio with reverse polarity.

Capacity

The amp hour capacity of the adapter depends on the type of batteries used.  Some examples might be:
 
#
Chemistry
Battery
Model
Volts
Amp hours
Watt hours
2 * 9V
Alkaline
Rayovac
A1604
18
0.6
10.8
2 * 9V
NiMH
Eveready
NH22
15.7
0.175
2.8
4 * 9V
Alkaline
Rayovac
A1604
18
1.2
21.6
4 * 9V
LiMnO2
Energizer
L522
18
2.4
43.2
10 * 1.5V
NiMH
Maha
2700
13.6
2.7
36.37
10 * 1.5V
Alkaline
Rayovac
815
15.8
2.2
34.8
10 * 1.5V
LiFeS2
Energizer
L91
RS 23-663
15.0
2.9
43.5

Using 12 instead of 10 AA batteries will not change the Amp hours, but it does increase the talk time because the cutoff voltage is increased.  For a comparison to the military batteries see my PRC-68 Family Batteries page.

17 Aug 2003 - the above table is based on the manufacturer's data sheets.  The capacity (amp hours or watt hours) increases if the current drawn is lower that that used by the manufacturer when they tested the battery.  I tested 8 each Powerex AA cells marked 1.7 Amp Hours using a simulated PRC-126 i.e. receive mode with no audio for 9 minutes at 40 ma and transmit mode for 1 minute at 350 ma.  This cycle was repeated until the battery voltage went below 10 Volts (low battery tone voltage).  The 10 cells (typo on the screen shot says 8 cells) put out 7.9 AH, they lasted for 22.4 hours.

19 Aug 2003 - Tested 10 each EverActive AA cells, 24 each blister packed at Wal Mart for $7.  Date code: DEC 2009. UPC: 81131 74129.  These lasted for about 24 hours using the same load as above and a 10 Volt cutoff voltage.  The screen shot shows 10.6 AH, but this is for a cutoff voltage of 8 Volts.  Using a linear interpolation gives about 8.4 AH to 10 Volts, so these low cost AA cells don't have much more than the 1.7 AH advertised capacity of the above Powerx AA cells.  Note that the voltage difference between the Rx condition and the Tx condition increases substantially the battery runs down.  When the battery reached 8 Volts the internal resistance of the pack was just over 10 Ohms.  After the test stopped and the battery had time to recover the terminal voltage climbed back to 12.3 Volts (1.23 Volts per cell) for dead cells.

Maximum Safe Battery Voltage

I have not done a test by burning out a radio so this is my best guess.

Some of the manuals show a 17 Volt Zener diode protecting the radio when external power is applied.  But a Zener does have some internal resistance so does not really provide a solid 17 Volts, so a little above 17 Volts may be safe.

Also, it depends on the batteries you use and how many.  NiCads and NMH batteries have a lower voltage than Alkalines.
you can safely use 12 NiCad or NMH batteries, but 12 Akalines may be too much.  Alkalines are about 1.5 * 12 = 18 Volts just a little too high.

Ordering

Related Products

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Squad Radio Battery Snap

The Squad Radio Battery Snap is also for sale as a seperate product. This can be used either to power a squad radio through the battery terminals or as a snap to charge Squad Radio Batteries.

Related Information

Back to Brooke's Products for Sale, Batteries, PRC-68 Family battery Portrait, Squad Radio DC Power Sources, PRC-68 Family of Squad Radios, Military Information, Pwesonal Home page

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created 21 August 2001.