The current packs I have are Spyder 6S 2600 25C in a 6S2P configuration on the E5.
That's a really interesting setup. What made you decide to run smaller packs in parallel versus a single larger 6S pack?
In part, those are the packs I fly on my Protos 500 (6S1P) and Trex 600 (12S1P), so they are packs that I have and 6S2P gives me flexibility to share packs.
I was also curious to see how a 6S2P setup would perform. Since total resistance for a parallel circuit with two packs is 1/(1/R0 + 1/R1), this configuration should result in a very low IR. For example, one of my packs has a measured total IR of 16 milliohms, another 14 milliohms. In parallel, this should yield a total resistance of 7.875 milliohms. The charger measures 4 milliohms total resistance. Another characteristic is that the current draw is split between each pack, so at a 120A peak, the draw on each pack should be 60A.
Given this, I was curious how the heli would actually perform.
My experience so far with this heli and configuration is limited to just a few flights, but my initial impression is that setup responds well and delivers plenty of power. I've attached a graph of the CC data. Packs were a little warmer than the ambient temp of 86F after that flight, the motor windings were around 120F, but the ESC was more like 150F on the heat sink. As you can see from the graph, the peak internal temp of the ESC is likely the limiting thermal factor right now.
I'm considering buying 6S ~5000 packs to run as single packs for comparison, but I'll buy higher C-rated packs.
A pair of the Spyder packs weighs 845g with XT60s, the parallel harness adds another 28g. So, compared to say a Glacier 6S 5300 40C, the 6S2P configuration doesn't have a weight or cost advantage. The same holds true if we were to compare a pair of Glacier 6S 2600 30C to the single 5300 40C pack. The single pack is certainly more convenient to load on the heli and charge. I'm expecting that the single pack will run a little warmer, but I'll also be curious to measure the power delivery and see if I notice a difference in flight.