TWListees, I'd like to share with you an account of my latest small, do-it-yourself project. My handheld VHF radio is a discontinued model, but when its 7.2-volt, 800-mAh, nickel-cadmium, rechargeable battery pack reached the end of its useful life, I checked the manufacturer's website and found that a replacement battery pack was still available at a list price of $99. On the other hand, a current-model handheld VHF radio from the same manufacturer, with a 1300-mAh, nickel-metal-hydride battery pack, was available elsewhere at a discounted price of $160. The current model also accepts alkaline AA batteries, which is a very useful feature. I was sorely tempted by the current model, but decided to explore the possibility of replacing the dead cells in my present battery pack. Disregarding the "Caution: Do not open ... " label, I opened the plastic case by inserting the tip of a wood chisel in the seam between the front and back halves of the case and tapping the end of the chisel handle with a mallet. I did this on the top of the case, so that the mark left by the chisel would not be visible when the battery pack was reattached to the radio. With the top seam opened about 1/8", I was able to pull the two halves of the case apart with my hands. Inside, I found a two-by-three array of six AA cells, held together by clear plastic tape, connected in series by spot-welded metal strips, with two spot-welded solder tabs hard-wired to a small circuit board. At this point, I had confirmation that the wood chisel had penetrated the case in the plane containing the long axis of symmetry of the cell array. Hence, there was little chance that the metal tip would have caused a short circuit, but if I had a suitable non-conductive tool, I would have used it. At a local Radio Shack store, I found 3.6-volt, nickel-cadmium, rechargeable battery packs for cordless telephones. These consisted of a one-by-three array of three AA cells, held together by white plastic shrink wrap, connected in series by spot-welded metal strips. One type, with a capacity of 600 mAh, only had spot-welded solder tabs. Another type, with a capacity of 700 mAh, had spot-welded solder tabs hard-wired to a small polarized plug. Apparently some cordless telephones have hard-wired battery packs, and others, like the two I have at home, use a plug and socket connection. Neither type matched the 800-mAh capacity of the original AA cells in my VHF radio, but I decided to press on regardless. For $10.49 each, I purchased two of the 700-mAh, pre-wired battery packs, to be connected in series for the required 7.2 volts. I cut the two wires of the original battery array at the spot-welded solder tabs, leaving almost all of the red (positive) wire and the black (negative) wire attached to the circuit board. On one new array, I cut the red wire at the plug and the black wire about 3/4" shorter. On the other new array, I cut the black wire at the plug and the red wire shorter. I stripped the insulation from the ends of the six wires and joined them in three twisted, soldered and taped splices: short red wire to short black wire, long red wire to long red wire and long black wire to long black wire. With two new three-cell arrays in place of the original six-cell array, I reassembled the plastic case with a little Duco cement. As I did so, I wondered why the radio manufacturer hadn't provided for easy cell replacement, similar to my cordless telephones. If I have any problems with the rebuilt battery pack, I'll let you know. Can anyone familiar with nickel-cadmium battery technology explain the difference between AA cells with 600-, 700- and 800-mAh capacities? Same size outside, but different sizes inside? Mostly lurking since 1 July 1997, Joe Joseph J. Blass Oak Ridge and Chattanooga, Tennessee