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:
Nowadays, they’re a bit less peppy:
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 fit 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:
That cracked faceplate isn’t the nicest thing to confront, but it’ll suffice until I get more motivation:
I’ve misplaced my stack of Round Tuits again…
The Smell of Molten Projects in the Morning 
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.
Here’s everything I know about it:
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!
A7002 sounds like a Goldmine part number. In any case, thanks for the info and pic!
And it is! Sold out, of course, which sometimes happens in a matter of days with Truly Good Stuff.