Hi Pgroom_68,
On the day that I had ordered my Big Lama I went to this website (
http://www.helidirect.com/index.php?cPath=38_235_622 ) and ordered 2 extra batteries, 3 extra sets of blades and most of the other spare parts such as a swashplate, blade grips, pushrods, bearings, inner & outer gear sets and battery holder. I would have also ordered another body, but they didn't have any in stock at the time. I figured that it would be better to have these spare parts handy then have to wait for them later.
As far as the batteries go, so far I am happy with the stock batteries, however I have checked several websites looking for a slightly stronger battery with the same dimensions as the stock one, but so far can’t find any. The exact measurement of the battery that comes with the Big Lama is 2 3/4" long, 11/16" high and 15/16" wide. Looking at the battery holder I would guess that the maximum battery height and width that would fit in there would be 3/4" high and 1 1/8" wide. Bear in mind that the battery has to be at least 2 ¾” long to fit across both ends of the battery holder, however it can be longer than that, just not shorter.
Forgot to mention that your wheel modification looks great!