[MRCA] Prc-25 battery question

[Glenn Little WB4UIV]

The batteries in the photo are questionable.
The best 18650 cells are 3500 mAh.
If you measure their true capacity, I would be very surprised if the 
capacity was 2200 mAh.
There should be a battery maintenance board in the battery pack that 
limits the charge/discharge rate and shuts down the pack on low Voltage.
With out the BMS there is an increased possibility of fire.

73
Glenn
WB4UIV


On 4/22/2026 11:31 PM, Clare Owens via MRCA wrote:
> I received this battery case with a NOS? PRC-77 from a Japanese ebay 
> seller.  It is for 4 18650 batteries and apparently was made by 3D 
> printing.  Seems to work fine and has the resistance in the 3V line.  
> Only problem is that the '25 and '77 are analog, with no low battery 
> alarm so it is too easy to drain the batts below their 2.5V minimum 
> and thus ruin them.  It is identical in size to the BA-5598.  And I do 
> not want to sell it.
>
> Clare. N2RJB
>
> On Wed, Apr 22, 2026 at 7:50 PM Tim via MRCA <mrca at mailman.qth.net> wrote:
>
>     Hi Dave ..My PRC-25 is powered by 2 “D” Cells in series (with a
>     DIY 1 ohm resistor in series) for the 3 volt 2DF4 TX tube filament
>     and two 6 volt, 4.5 A-H Gel Cells (Power Sonic PS640F-1) in series
>     for the rest of the electronics. It all fits in the stock battery
>     box and I can charge the Gel Cells by connecting pin leads to the
>     Power connector female pins when the Z-1 plug is removed.
>
>     The 1 ohm resistor in the filament line is needed to drop some
>     voltage (from fresh batteries) to the tube filament when it is
>     cold-started. Mine is made from about 8 feet of 30 gauge magnet
>     wire wound on a high value resistor as a form.With my occasional
>     usage the D Cells last "forever".
>
>     Tim
>
>     N6CC
>
>
>
>     On Wed, Apr 22, 2026 at 3:37 PM KD2GIY via MRCA
>     <mrca at mailman.qth.net> wrote:
>
>         On my trip to MD and DE I came across a very good deal on a
>         working prc-25 on the Jeep dock.
>
>         I understand the radio needs 2 different voltages and it would
>         be a pain in the ass to fabricate this.
>
>         My question is, does anyone have for sale a drop in battery
>         insert for this radio or can let me know where I can find one
>         on the internet?
>         I've seen pictures of some that take d batteries.
>
>         I have looked and cannot find anything but used original dead
>         batteries.
>
>         Thank you for your time.
>
>         Best regards
>         Dave
>         KD2GIY
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-- 
-----------------------------------------------------------------------
Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIVwb4uiv at arrl.net     AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA-LM    ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
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