[MRCA] D Cells in Parallel

[Ray Fantini]

Finding matched cells must be a real challenge with the “Dollar Store” batteries! I have run things like a TBX that draws 330 Ma from one D cell and never had any issues.

Ray F/KA3EKH


From: mrca-bounces at mailman.qth.net [mailto:mrca-bounces at mailman.qth.net] On Behalf Of B. Smith
Sent: Monday, April 23, 2018 1:30 PM
To: mrca at mailman.qth.net
Subject: [MRCA] D Cells in Parallel

     Its military rally season and just a word of warning about using D cells in parallel. Several of us have experienced "D Cell Runaway" when using two D cells wired in  parallel.  Evidently one cell charges the other and the battery chemistry changes resulting in a very low resistance of one battery resulting in high current drain of one of the batteries and then the other one goes South.
      Does this happen every time you use them in parallel?    Ans. No.    It is random. As a possible preventive measure when using cells in parallel always use fresh batteries and from the same package and date code. Also test the batteries under load to make sure that they are equal. Do not mix different brands of D cells. Do not store the batteries in a hot environment prior to use such as the rear of your vehicle.
     But these new  "Alkaline-Manganese Dioxide" batteries have plenty of capacity and a single cell can easily power the typical 1.5 volt filament circuits found in most of our older military radios. So why bother using two batteries in parallel?

       When using the FT-501 holder for the BC-611 - - - I would modify the fixture to  just utilize  1 D cell.

      This runaway phenomenon usually  occurs with the radio  power switch OFF!

WARNING: DO NOT STORE any radios or battery packs with D cells in parallel      -      -     - REMOVE the batteries.
Z

[cid:image001.gif at 01D3DB0C.90538700]




set on or off
BC611 battery adpataer
do not store


duracell
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