Which brings us to the topic of high voltage systems.... Why do we need Series Wire multiple 3S, 4S, 5S and 6S packs together to make these absurdly high voltages?

Simple explanation... POWER.

Remember that P = I x V.

Now, look at I (current in amps), and consider the commonly available Lipoly Battery pack. Notice as you browse all the Lipo manufacturer websites that the largest ones are 8000 mAH. Also note that these fatty packs cost more than several tanks of gas in a big SUV.

The large capacity cells get really expensive. Not only that, but they get really HEAVY too. So, if you look you'll find it's cheaper to buy a pair of 5S packs and wire them in series than it is to buy a special purpose (low volume) 10S pack. Do the math...

Now consider the POWER part of the equation. Assume you have a 20C 8000mAH pack. At 3S the POWER potential is:

11.1V x 8.0AH x 20C = 1776 Watts.

Now, think about the Wattage needed to fly a big 40% wieghing in at maybe 42 lbs. We need at least 10 W/oz (160 W/lb) to fly 3D, and better 12+ W/oz (~200 W/lb) for nice performance. So, how much power do we need?

P = 200 W/lb x 42 lbs = **8400 Watts!**

So, you can see that going big on the battery capacity becomes a limit, and to increase the POWER you have to increase the VOLTAGE, instead of the Current.

That means you MUST Series wire batteries to get enough juice for high-power applications.

Also note... look at the Outrunner Motors for big applications. They have really low kV ratings. They are designed for High Voltage systems, because they know that nobody is gonna make a 3S1P 40,000 mAH pack, LOL.

Also, consider the Amperage you would need to manage if you were to use 3S or 4S at over 8,000 Watts, remember I = P / V:

8,400W / 11.1V = 757 Amps on 3S Pack

8,400W / 14.8V = 568 Amps on 4S Pack

Amperage equates to weight, in wire gauge and in component size. Motors and ESC would have to be monsterous to manage current this big. Not practical for a light build on any aircraft.

So, you can see that super-high output systems must run on high voltage to manage all the key factors: Weight, Cost, Efficiency and Power.