PRC-25 & PRC-77 Battery Adapter  2577BA

©Brooke Clarke, N6GCE 2002


Prod Ver 6.2
one Batt
Prod Ver 6.2
Foam removed from batt box
Prod Ver 6.2
3 5/16 x 9 1/2"
Prod Ver 6.2
2 3/8" x 9 1/2"
2577BA - 2 3/8" hi
BA-4386 - 2" hi

History

This page shows where the current 257477BA came from.  The version shown here required removing the rubber strips from the battery compartment in the PRC-25 or PRC-77 and could not be used in any of the PRC-74 battery boxes.  It is no longer being made.

Proof of Concept for Battery Adapter This is the very first Proof of Concept adapter made by hot melt gluing dead "D" cell batteries between plastic sheets.  On the right is a clear plastic where the socket would be mounted.  The batteries were dead back in 2001 and today (May 2007) one of them is leaking.  This adapter got notched during the development of the 257477BA.

Background

There are a number of PRC-25 and PRC-77 radios that don't have a reasonably priced source of power.  New batteries are difficult to buy and expensive.  The "Fresh" still in the plastic wrapper BA-4386/PRC-25 batteries being offered on eBay are way out of date and typically are DOA.  The BA-5598/U has been banned in two issues of PS magazine for use on the PRC-25, probably because it does not have any limitation of the filament current like is in the new batteries and in the BA-4386/PRC-25.  Without some current limitation a cold filament will draw an enormous amount of current thereby decreasing the tube life or even burning out the filament.

This adapter has a filament current limitation which is mandatory.

Holds 10 each "D" cells in series with a tap up two cells for the filament supply.

2577BA requires removing the foam strips in the bottom of the CY-2562/PRC-25 battery box because the adapter is 2 3/8" high whereas the BA-4386/U is 2" high.  If you don't want to remove the foam strips use my 257477BA battery adapter.

2577BA User Comment

"I put the prc25 on a workbench in our radio shop after the test, and found that with the battery adaptor and fresh alkaline energizer batteries, I was putting out 3.5 watts and the receive sensitivity was about .45 uV ..

Not bad performance .. I think I had checked the radio in the past with a magnesium battery and got about 1.8 watts out, so the higher voltage of 10 1.5 volt cells being 15 volts probably raised the performance of the radio a little.." Trish WA6UBE moderator of the Army Radios mailing list

2577BA Instruction Sheet

Battery Options

The 2577BA shipps with no batteries, it's up to the user to select and install the batteries.  Do not mix battery types!  All 10 cells should be of the same model number and date code.
 
Manufacturer
Chemistry
Model
Amp Hours
Weight/each
Total Adapter wt
Eveready
Duracell
Rayovac
Radio Shack
Alkaline
A95
MN1300
813
23-870, 23-880
18
5 oz
3.56 lb
Ray-O-vac Renewal
rechg Alkaline
713
7
4.4 oz
3.25 lb
Radio Shack
NiCad
23-123
2.0
oz
lb
Radio Shack
NMH
23-519
4.5
4oz
3.0 lb
King Cell
NMH
?
7.5
?
?
Saft
(for reference)
LiSO2
BA-5598/U
Taboo on PRC-25
2 * 7.5 = 15 AH
23.2 oz
2.90 lb 

The Alkaline offers the highest AH capacity and the lowest single use cost.  The rechargeable battery offers a lower amortized cost because of the reuse but at the expense of lower AH capacity and possibly more weight and higher up front cost.  The LiSO2  has very good AH capacity and is lighter than all the others, and that's why the military uses a lot of them, BUT should not be used on the PRC-25.

Note: A number of companies offer "D" cells that are in fact "C" cells with an outer wrapper. For example the Radio Shack 23-124 "C" NiCad cell and the 23-123 "D" cell both have 2 AH capacity and both are priced at $ 6.99 for two.  In the case of the 23-520 3AH "C" @ $14.99 for two vs. the 23-519 4.5AH "D" @ $14.99 for two, the "D" cell is the better buy.  Just be alert to what AH rating you are getting for the dollar.
Note: It's very difficult to test any LiSO2 battery.  If you are using the BA-5598/U in a PRC-77 on an intermittent basis you will have no way to know if the battery will suddenly quit.  With older batteries like the BA-4386/U you could test with the PSM-13 and have a pretty good idea of how much charge was left in the battery, but you need a TS-4403 to check LiSO2 batteries and these are very hard to get (even for the U.S. military).

Testing

While trying different battery chemistries I found that neither the TS-183 nor PSM-13 do a reasonable job.  The TS-183 uses a 298 Ohm load (about 50 mA) and the PSM-13/U-410 uses 5 Ohms ( 3 Amps) as the load.  One is too little and the other is way too much.
To get a fair comparison between different battery chemistries the load should be close to the actual radio load, somewhere around 1.1 Amps would be good.  Since 1 Amp at 15 Volts is 15 Watts a practical  and low cost way to make a load is to use a couple of 10 Ohm high power resistors like the Radio Shack 271-132 load resistors.  Here is what the data looks like:
 
 
E95
Alkaline
 
Rayovac
Rechargable
 
RS
NMH
 
BA-4386
old Mag
Load
V
 
V
 
V
 
V
Open
15.8
 
15.7
 
13.9
 
17.0
20 Ohms
 
 
 
 
 
 
 
1 A
13.4
 
12.8
 
13.5
 
12.3
16 Ohms
13.4
 
13.7
 
14.0
 
12.0
2 A
11.3
 
10.8
 
13.0
 
10.2
3 A
9.3
 
8.8
 
12.6
 
7.3

The BA-4386 terminal voltage is a strong function of what the prior load has been.  If first connected to a 1 Amp load the chemistry does not fully activate and the voltage is lower than when the battery has seen a heavy load, like the PSM-13/U-410 provides.  But most radio users do not condition their BA-4386 batteries so this is not a fair way to test.  This effect is why the BA-4386 data does not seem consistent.

Where BA-4386 is used

These equipments may or may not accept this adapter because the 2577BA was designed to fit into the CY-2562/PRC-25 battery box of a PRC-25 and/or PRC-77 and is traller than the BA-4386.
 
Model
Description
Function
GRA-114
Sound Ranging Radio Data Link
?
KY-38
Voice security device, Nestor, Man portable w/PRC-25
No
KY-65
Secure Voice Device w/GRC-206, PRC-104
?
PPS-15
PPS-15A
Radar Set
?
?
PRC-25
VHF low band tranceiver
2577BA OK
PRC-74 in the CY-6314
wing nuts & moving plate
HF tranceiver
No only the
257477BA is OK
note 1
PRC-74 in the CY-6314A
hinged seperator
HF tranceiver
No
PRC-77
VHF low band tranceiver
2577BA OK
PRC-1077
VHF low band tranceiver
?
PRC-1088
VHF low band tranceiver
?
PRC-1099
HF tranceiver
?
PRD-10
VHF Manpack Radio DF
?
PRD-11
VHF Mini-Fix Radio DF
?
PSN-6 Loran C & D 
receiver that mates with the PRC-25 or PRC-77
2577BA OK
URR-69
?
?
USA-32 
?
?
USQ-42
VHF high band outdoor intrusion receiver
?
USQ-46 & TS-2963/USQ-46
VHF high band receiver & Transmitter (TS-2963)
?
URC-110
Radio Set Line of Sight or SATCOM
?

note 1 - The CY-6314 battery box has a notation:
"One battery operation: plug into J2 and secure with retainer"
"Two battery operation: mount back to back, and plug into J2 and J3 and secure."

Ordering

Version 6.2 has been shipping since 24 July 2002
Version 6.5 is now called the 257477BA.


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, Home page

This is the  time this page has been accessed since since 14 Feb 2001.