Originally Posted by flohio117
...But every motor and prop combo has its sweet spot where basically it's giving you the best combo and flight times. It's just hard to find sometimes.
That's probably the best statement. I just takes testing, recording, experimenting to find what motor/prop, battery combination gives the performance and flying time you're satisfied with. I'm using an Eagletree data logger to record my volts and amps in flight so I see exactly what the system is doing in operation.
In theory, 4S is more efficient than 3S. We actually fly more by power (Watts) than amps. Simple math is IxE=P (amps x voltate=power). Let's say you need 300W to fly how you like. WIth a 12v system you divide P/E=A (300W/12V=25A). Now take that to a 4S system @ 16v...300W/16=18.75A...a 6.25A reduction which equals longer flying time. Now consider larger, heavier batteries will require more power to lift the extra weight and you could end up with no significant gain or flying time.
I posted some of my 4S, 750kv, 9x5x3 time/power data earlier in this thread....without FPV gear installed. Now that I've added extra weight I will need to test again with different props to see which gives the performance and flight time I'd like. My goal is to achieve ~12 minutes full FPV flight time with the idea of flying only ~10 minutes with a few minutes of reserve. More testing to do to get an idea what my system is able to provide.