This is going to be a fairly short write up as this is still in testing phases.
My first build has yet to come to life, as I’m waiting for parts to arrive. I luckily live about 30min from the US West distribution center for Hobby King. I was able to go pickup basically all of my electronics. I took a risk ordering some components I wasn’t sure were going to work together properly for ESK8. In the mean time, I decided to get soldering and test a bit.
I’ve seen the idea kicked around about using boat ESCs in ESK8 setups. It seems as though a few guys on YouTube have had some success. They’re a cheap solution for 6S capability, most have proper inputs for throttle, brake, and reverse, therefor ready to be used with a car TX/RX. Now, 6S is pretty meh, and for a few bucks more you can get a 6S car ESC such as the FVT, that’s been proven to be a budget ESC solution for ESK8 usage.
Most of us want more than 6S. Only and handful of options are out there to safely and reliably power ESK8’s with 8, 10, and 12S battery setups. VESC is known to be the “BEST” solution out there, but unfortunately has gained a somewhat bad reputation of frying due to user error. It’s a fantastic system built from the ground up with ESK8 in mind, however in not necessarily a plug-in-play solution. Not only this, but it comes with a pretty hefty price tag as well. Other companies such as Torque Boards, Alien Power Systems, etc… Have developed up to 12S capable car style ESCs. However, again come with a nice price tag.
I personally wanted to truly build a budget board, with at least 8S capability, and the safety and reliability of at least a car ESC. With a heavy background in competitive surface RC, short course, buggy, truck, you name it, I decided I could probably make a plane/heli ESC fit the bill. They’re spec’d well. VERY well. A HV (5S-12S) air ESC will run you in the range of $80-120.
I went with this, Turnigy K-Force 120a OPTO ESC: http://www.hobbyking.com/hobbyking/store/__38782__TURNIGY_K_Force_120A_HV_OPTO_V2_5_12S_Brushless_ESC.html?strSearch=k-force
Notice how similar this ESC looks to Torque Boards 12S ESC. The description in fact is almost identical. I suspect they share the same OEM, however TB has reflashed the ESC possibly? I digress.
I got the ESC all wired up, a BEC was needed as the ESC does not have one. First test, turn everything on, motor starts spinning up to what seems to be half throttle. This was the problem I was expecting. The ESCs end-points out of the box for planes and helis, are drastically far off from a surface TX. Not only this, but these ESC’s also do not have input for braking from the transmitter. It does offer a programable “brake” which is basically a drag brake, ranging from soft, normal, to hard.
A surface radio’s “bottom throttle point” is in the middle where the trigger rests, “top throttle point” is fully depressed toward the grip, and “brake/reverse point” is forward with the trigger. With no brake reverse endpoint to be set in the ESC, I had to crack into the radio housing to change the throw of the trigger assembly.
I already repositioned the spring prior to this photo, it was originally connected vertically behind the trigger just in front of that phillips head screw. Above the keyed shaft the trigger slides onto is a retaining bumper. This piece allows the trigger to sit neutral in the middle, and have resistance when the trigger is moved backwards or forwards. Removing this bumper allowed the trigger free range of movement. A reposition of the spring, and we now have a linear throttle throw from top to bottom.
Power on the ESC and rescale the throttle top and bottom endpoints, and boom. We have a perfectly functioning high voltage ESC, aside from a proper trigger actuated brake. I will be doing testing to see how the drag break performs, or somehow find a way to potentially reflash the firmware and add a brake/reverse input.
Overall, success. 12S capability for $120, no complicated programming setup or risk for toasting the board like a VESC. THIS IS NOT A VESC ALTERNATIVE. It still does not have the features VESC offers especially for ESK8, but hey its cheap and simple.