A point not covered so far is that you what a RX pack capable of at least 600MAH. Your telephone batteries are not going to supply that capability even ganging them together fora usable voltage. A NIMH pack of 2300MAH @4.8 Volts is a good, inexpensive Choice. I've bought them for as low as $10 each delivered. 1000 MAH Nicads or greater is needed if you are going to do more than a couple flights a day.

Another point is chargers. IMHO, a good peak detection charger is a must, one that will charge the type battery you have. This is really important for NIMH as an over charge wild toast the pack. Idid that with my first one for my 9C TX. Charged it and flew it for a couple flights. Got home and "topped it off"on the wall wart over night, didn't get to the field the next day so Ileft it on the charger. The next day was a fly day and about three minutes into the first flight the low battery alarm went off on the TX. Luckily Igot the plane down. Checking the pack showed two cells gone, so my 8 cell pack was down to a 6 cell.

With Nicads you can leave them on the trickle charger for a few days without fear of killing them, but you are never sure how full the tank its, so a good peak charger solves that issue quite nicely.

Batteries have cost me a plane and almost a second. Short cuts and salvage batteries are just not worth it. If a battery starts giving a problem, in the recycle bin it goes. Saving a couple bucks on a battery to loose a few hundred wrapped up in a plane just isn't a good trade.

Don