In this post, I will be reviewing the Firefly 30A ESC  made by VGoodRC. This is a very interesting ESC as it has a 32-bit processor, dedicated gate drivers and hardware PWM output to the FETs. More information on these ESCs is available at this RCGroups thread. I would like to thank VGoodRC for developing these ESCs and offering samples and RCHyper for procuring samples for me. I got these ESCs free of charge but I will do my best to keep this review unbiased.

Technical Specs

The Firefly ARM ESC comes in the following variants:

  • Firefly 10A opto (Size: 11*20mm), 2-4S
  • Firefly 18A opto (Size: 12*22mm), 2-4S.
  • Firefly 30A opto (Size: 14*27mm), 2-4S (Weight: 8g)
  • Firefly 30A opto (Size: 21*35mm), 2-6S

I opted for the 30A 2-4S version as 30A is what I am currently running on my bigger quad (Reptile 500). Honestly, with 2212 980kv motors, even 18A would have been enough. However, even one of these 30A ESCs would be much lighter than the ESCs I am running now and since weight is not so critical I’d like to leave a wider margin. I chose the 2-4S version as I am working on a custom 500 size frame and these ESCs are narrow enough to fit in the 16mm CF tubes I am planning to use for the arms.

First Impressions

My first impression of these ESCs was very good! They come in the typical anti-static bags along with a decently clear instruction manual. I also got a programming card, something I’ve never needed to use before. One thing that struck me immediately is the size; compared to the massive 30A SimonK ESCs I am using now, these are absolutely tiny! In fact, they are comparable in size with the Little Bee 20A! They weigh only 8g each which is quite impressive! Another thing that stands out is the quality of the wires on these ESCs- even the signal leads are nice silicone.

Firefly 30A 2-4S (top) Little Bee 20A (bottom)

Firefly 30A 2-4S (top)
Little Bee 20A (bottom)

IMG_20160311_163332IMG_20160311_163159

Flight Test

I installed this quad on a Reptile 500 frame running SunnySky X22122 980kv motors and an APM 2.8 FC. I used to find it quite boring to fly (more so after I built my ZMR) as it wasn’t very responsive and felt liked it lacked power. I also had some oscillations on fast yaws that I was not able to tune out. However, just by swapping in the Firefly ESC I noticed the following improvements:

  • The quad is feels much more smooth and responsive. Loiter/ Position Hold seems more solid and auto-landing is definitely smoother.
  • I can do some fast yaw spins without any noticeable wobble. I still need to tune this a bit as I have some overshoot but it is a very noticeable improvement.
  • Flight time – I usually get around 11-12 minutes flight time, a good chunk of which I would spend hovering in Position Hold. Now I get 13 minutes of relatively hard flying, while using about 3500 mAh of a 4000 mAh pack. I did notice that my motors are heating up more probably due to the strong braking on these ESCs (they stop a 10-inch prop dead as soon as I disarm).

Verdict

This ESC has its fair share of pros and cons. The pros include:

  • Excellent performance and small form factor.
  • Oneshot42 support + planned Multishot support (in future firmware updates)
  • Reasonable price.
  • As simple to set up as SimonK ESCs (for most users) but with a much more powerful processor (maybe even overkill) and features like dedicated gate drivers, hardware PWM etc. You can just calibrate them and fly. The only reason I used the programming card was to change the direction of a couple of motors (because I was too lazy to desolder and I wanted to see how user-friendly the programming card is).

There are a few cons as well:

  • Some users are reporting major sync issues. VGoodRC is apparently working on a firmware update to fix this.
  • You can’t use a stock Arduino nano/FTDI/CP2102 to flash – you either need the USB linker or a DIY circuit with the CH340.
  • The programming card is a bit inconvenient and there is no passthrough feature for flashing/ changing settings. Could be a deal breaker for those who direct solder their ESC signal leads onto the FC.

Overall this ESC seems like an excellent option for larger multirotors, such as those used for aerial photography due to the extremely smooth throttle response. It would also be good on smaller quads for those using pins on their FC or those who don’t want to fiddle around too much with programming.