FC1002 Frequency Counter Battery Pack

The main reason for taking the FC1002 frequency counter apart was to replace the failed quad-AA NiCd battery pack. Rather than buy new cells with tabs, I recycled some low-discharge “ready to use” NiMH cells from the heap. Back in 2009, they looked like this:

Tenergy RTU Pack A Tests - Aug 2009

Tenergy RTU Pack A Tests – Aug 2009

Nowadays, they’re a bit less peppy:

Tenergy RTU - 2014-01 - loose cells

Tenergy RTU – 2014-01 – loose cells

The red blooper shows that you can’t trust a smart fast charger to get the right answer; it concluded that pair was fully charged. After the discharge test and an overnight C/10 charge, they regained as much enthusiasm as they’ll ever have.

They have slightly less capacity than in 2009 and also a somewhat lower terminal voltage. That shouldn’t matter here, as the frequency meter has a power supply to take care of that problem.

Although I’ve sometimes been able to (quickly!) solder directly to ordinary AA cells, a trial run on a defunct RTU cell showed that wasn’t going to work on whatever variety of steel they used, no matter how much I scuffed it and despite using aggressive flux that normally blends silver solder onto stainless steel.

Fortunately, the top half of a four cell case fitĀ exactly in the space available, so I used woven copper fabric tape inside the case to interconnect the cells, then lashed everything together with the obligatory Kapton tape:

FC1002 Frequency Counter - battery pack

FC1002 Frequency Counter – battery pack

That cracked faceplate isn’t the nicest thing to confront, but it’ll suffice until I get more motivation:

FC1002 Frequency Counter - repaired

FC1002 Frequency Counter – repaired

I’ve misplaced my stack of Round Tuits again…

  1. #1 by madbodger on 2014-01-14 - 08:53

    Woven copper fabric tape? What’s that? I’m familiar with foil tape, Z-tape, and conductive fabric, but adhesive conductive fabric? That sounds USEFUL.

    • #2 by Ed on 2014-01-14 - 09:26

      Here’s everything I know about it:
      Copper mesh tape
      It’s an inch wide, rolled on an ordinary 3 inch core, and was (obviously) surplus. Some rummaging around suggests that 3M Copper-Coated PET Cloth Fabric Tape X-7001 might be close; the surplus part number was A7002.

      Ordinary copper foil tape would work, but I figured the fabric would be flexier and have more contact points… and I must use the stuff every now and again!

      • #3 by madbodger on 2014-01-15 - 10:32

        A7002 sounds like a Goldmine part number. In any case, thanks for the info and pic!

        • #4 by Ed on 2014-01-15 - 12:33

          A7002 sounds like a Goldmine part number

          And it is! Sold out, of course, which sometimes happens in a matter of days with Truly Good Stuff.