When I was building my 250 class quadcopter I wanted to make that cheap. So, I've bought cheap ESC: Turnigy Multistar V2 10A ESC for S2-3 with 2A LBEC. And yes, they are cheap: slightly less than 8EUR per piece. With preloaded BLHeli software. Cool, isn't it? Well, not so cool after all, but first things first.
Preloaded BLHeli software (version 13.1 in the ones I've ordered in late June 2015) simplifies a lot. No need experiment to upload BLHeli and 1-wire interface is available from the start. Also update to BLHeli 14 was pretty simple without any glitches. Unfortunately, there is a reason those ESC are so cheap...
After 2 months of using them in my 250 quadcopter I can state the following:
- They are cheap all right,
- None of them burned yet so it's a good sign,
- Preinstalled BLHeli and easy to upgrade
- 10A is not much for a quadcopter needs, slightly higher max current would be welcomed . But this is my fault, not those ESC,
- they do not support Damping Light, so no active breaking on those ESC (booo),
- OneShot125 on those ESC behaves strange when throttle is below lower limit. They screech. Fortunately nothing bad happens in flight,
- 2A LBEC regulator is in fact double LM7805. And it heat a lot.
Final conclusion: reliable and cheap but I would not decide to buy them again. For only a few euro more you can have much better ESC.