What is the best way to connect the batteries together? Solder or spot weld?
Soldering to cells may destroy the nylon seal. They should always be welded together. You can buy cells with solder tabs already welded on and then interconnect them with small pieces of #22 wire (stranded). It is better to buy the packs already assembled and then just add your own connector. They are available through Tower [Hobbies] in this way. There is also an ad for FMA direct in R/C Report (August 96) where they are sell receiver packs for $11.95 and transmitter packs for $24.95 including the connector of your choice.