Wow...that stock GT pack is using either Sub A's or Sub C's (can't tell size by the picture)! I always heard it had AAAs in it. No wonder it's heavy! The picture confirms it does have a charging circuit behind the plug. That's why I have to charge mine via the battery terminal leads on the pack using my own charger. I'd put some boot grease (dialectric...sp?) on the battery terminals of the AAAs before putting them into the holders. Since the cells aren't being soldered together they can build up carbon between them and the holder's contacts, causing a short. We do this in RC with our transmitters 'cuz a power loss while flying wouldn't be fun.
That's a great job, but I'd also try a 2000 to 2500ma nimh AA as 8 should work OK so long as the capacity is high enough. They should hold their voltage better with a high capacity. Remember, even though nicads or nimhs are listed at 1.2 volts per cell a fully charged pack will often read much higher than that, at around 14 volts or so. A lower capacity cell will also sag in voltage much faster than a higher one, so you might find that 10 800ma AAAs has less run time than 8 AA 2000 (or higher) cells.
A good source for rechargable would be Hobby City or BatterySpace.com. Battery Space will even solder custom packs together for you if you want and add a connector if need be. If you are set on using 10 AA batteries I'd get the highest capacity you can find from one of these sites. Walmart sells 2500ma Energizer AAs if you don't want to order somewhere.
Better yet, as Kared and I have been talking in PMs, lipos are so much lighter. The rule of thumb is normaly half the weight and double the capacity compared to nimhs or nicads. He's (I think) going to use a 1450ma 3 cell from hobby City that should fit inside the battery door on his older Sovereign. I'm guessing he might save as much as 5 or 6 or more ounces over the stock rechargable pack, as the 2200ma 3 cell lipo I plan to use is going to save me over 3 ounces. These are packs I have on hand for RC planes otherwise I would use a smaller pack. I'd suggest a pack smaller, around the 1450ma, as it'll offer very long run times and shave a good bit more weight. I plan to just velcro mine to the top of the GT box (if the box is on the shaft) and use two mini alligator clips to hitch to the battery terminals on the bottom of the box. No need for the battery holder and that'll save a little more weight. The most important thing is to never short a lipo's leads together. Never overcharge them, and never drain lower than 9V. A 1450ma pack should give about 29 hours of run time, so to be safe I'd recharge very two hunts or so.
I'm going to throw together a tutorial on this soon. Maybe today, with a good cheap charger, cheap lipo options, etc. An $8 lipo and a $10 to $35 charger will get you less weight with more capacity, faster charge times, and so on. Again, don't mess with these things unless you know what you are doing.
