RE: Spektrum DX-7
Richard, sorry to hear about what happened. One simple test for peace of mind is to charge your pack to the level you believe your battery was at, install an inline amp/volt meter and with some load on the servos check your voltage in real time. A vmeter is worth the 35 bucks and will tell you a LOT about whats happening with your system. I did this and found that even with a 6v JR pack (high impedance) I was getting some pretty low voltage readings while just stalling 2 of my 5 digitals.
So, I went with nobs high-output 6v packs with 22 guage leads and a heavy duty 4 pole EMS switches with 22 guage wire. The interesting part is that this stuff cost less than the JR stock components I was running. Funny how that workedout. Now, I can easily service 8 amps to my rx and that's more than my 5 DS 821's can pull when completely stalled.