A couple of additional observations and considerstions:
When the payload is a battery adding extra power, the 1.
2s/g flight time loss is more than offset by the gain in flight time from extra power. On the P3P and
P4, I added 500g of weight in two external 2800 mAh batteries comprising 5600 additional mAh of power. Stock I was getting 18 minutes at a continuous 30mph. With the externals hooked up under the same flight conditions, I was getting 27 minutes, for a roughly 50% increase in flight time. If the 1.
2s/g loss of flight time is accurate, by adding 500g of weight, I lost 10 minutes of flight time, so the 9 minute gain was from adding battery power capable of delivering 19 minutes more of flight time, which is roughly correct. The stock battery was 4300 mAh on the
P4, and I was adding 5600 mAh. Roughly a 50% increase in flight time by adding 130% of the stock battery power. That was the sweet spot for me, factoring in additional battery weight and highest mAh available per gram of weight in externals.
Using your 100g estimate of dead weight, and the 1.
2s/g loss of flight time from the Phantoms, that would only be a 2 minute loss (120 s) rather than 10 minutes, before the gain in flight time from extra battery power is taken into consideration. I just question whether a power bank can supply the power at a fast enough rate to supplement a drone battery during flight!
