You can find most of this info w/ google and a little common sense.
I purchased a dewalt 36volt pack, made out of 10 a123 cells for like $80 and used 6 of them to make my pack.
You can find them on ebay for around that price. Anything under $100 shipped is normally a decent price. If you are looking for a
2s2p pack for 4wd buggy then you could just split the cost w/ a friend.
Be sure to do your research on these cells before you take apart the pack. There are sites on breaking them down. The two pieces of information you will need though are to leave the tabs that come w/ the cells on them, just cut them if you want to take them apart or leave them togather instead of using battery bars, because you can't solder directly to the cells so you solder to the tabs & do not twist the tab, twisting it can cause the cells to dead short. Do not cover the little blimish w/ solder, that is how the cells vent.
How to build a saddle pack:
required
*4cells,3 long pieces of wire, two battery bars, plug,shrink rap
All soldering will be done on the tabs & will not be over the small blemish in the middle of the cells.
1.take two cells and solder the + to the - using a battery bar(this will be side 1, repeat w/ the other two cells.(side 2)(the more you wire + to - the greater your voltage)
2. take a piece of wire that reaches across the chasis and connect the wire to the + of (side 2) to the + of (side1).
3. repeat this process for the neg.
4. repeat this process again, you can use a lighter piece of wire for this(balancing plug), with the side the battery bars on on. Run it from battery bar to battery bar.
5. Now remove the rubber off the + wire in the middle for your plug. and solder the plug to it there.
6. repeat step 5 for the neg.
(don't let the + and - wires touch, these are just like any other +&- wires on a 6cell stick.)
Now take the 3rd wire and stick a FEMALE PLUG ON IT(you want to make sure that the wires are not going to dead short when they touch since you have an extra wire. Often times I zip tie the two plugs away from each other on the car.
7. shrink wrap the cells if you want too.
For building 3p2s pack(perfect for 2wd truck or buggy), you will have to lower the sides of the battery trey just use a cheap solding iron and melt the sides down, much easier then dremeling them down. You can see what i'm talking about at
thedunemaster.com (more of those expensive packs)
1. zip tie 3 cells togather w/ the + ends all facing the same way.
2. strip down a nice thick wire and use it as a battery bar to connect the 3 cells + side.
3. repeat for the - side.
4. repeat steps 1,2,&3 w/ the other 3 cells.
5. take a wire and solder the + side of pack 1 to the -side of pack two.(short wire) and another longer wire from any of the cells in the middle(balancing plug).
then bend the wire connecting the sides so that the cells make a straight line.
6. run a wire from the free sides to your plug.
7. Now shrink rap it.