Cheap reciever packs for park flyers

[ButtonFly]

Being a college student, and very cheap, I have found a possible alternate source for reciever battery packs, rather than ordering a nicad pack and waiting for it, or paying dealer markup. I wanted a pack of about 150 mAh for a Guillows Thomas Morse I am working on for a peewee .020 engine. I bought a RayoVac Ultra Nickel Metal Hydride nine volt rechargeable battery at WallMart for about . Ripped off the metal case, and made a note of which end was positive. A nine volt is made by stacking seven cells together. I took a knife and broke the pack so I had one pack with four. One cell ends up destroyed in that process as you have to stick the knife in it. So you have one pack with four, and two more useable cells... trim the plastic, and rough up the metal contacts and solder leads onto them, making sure of your polarity. The battery is about seven dollars, and whatever you use for a connector is your choice. I sacrificed a fried servo connector. Hope this works.

[Jim]

I bought one of these batteries yesterday with the intent of (experimentally) using it for a motor pack. I removed the metal wrapper to save weight and planned to solder a JST connector w/wires to the existing "tabs". When I tried to solder it, I couldn't get the solder to stick to the tabs; they're made of stainless or something. How did you solder yours? I thought about removing the tabs and trying to solder directly to the cell's end plates but am a little worried about destroying the cell doing this. Also, I noticed that the clear plastic cells were wrapped in some kind of foil tape. I removed this (to save weight,you know) then I began wondering if maybe that was there to prevent light from damaging the cells or something. Has anyone ever heard anything about NiMH cells being light sensitive? I probably should have left well enough alone and just used a 9V snap connector soldered to the JST wires!
Thanks, Jim

[ButtonFly]

I think the tabs had chrome on them, and it did not want to be soldered to. Rough up the tabs with some 100 grit, removing whatever keeps it from sticking, and the solder should stick fine.