Running Packs in series or parrallel

[starscream]

When it comes down to it, there is no performance advantage between the two configurations in your example. Both examples have a total of 8 4000mAh cells. The only difference is the way you arrange them. Personally I would rather have a 4S1P 4000mAh pack than a 2S2P 8000mAh pack as a I would have more use for a single 4S pack than a 2S pack. For example, I could run a single 4S 4000mAh pack in my Ofna CRT.5 and later run both 4S packs in parrallel in my Revo.

A potential issue could be your charger's capabilities. If your charger can not handle 4S then you will either need a new charger or run the 2S2P configuration.