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When building a robot there are a wide range of ESCs on the market. The primary vendors in this article are The Robot Marketplace, (robotmarketplace.com) FingerTech Robotics, (fingertechrobotics.com) Equals Zero Designs, (e0designs.com) and BotBitz. (botbitz.com)
The ESCs presented here are being discussed from the perspective of their practicality in robots weighing 30lbs or less.
Name: BotBitz 10A ESC
Specs:
Voltage- 3V – 12V
Current- 10A peak
Dimensions- 0.91 x 0.71 x 0.32 inches
Weight- 9g
Cost- $15.00 AUD
Comments- BotBitz approaches the ESC market from an unusual angle. Their motor controllers are actually reprogrammed Chinese brushless ESCs. The reprogramming is used to convert them to dual direction brushed motor controllers. Recycling these ready-made, mass produced motor controllers and reprogramming them puts BotBitz on the bottom of the price range while still having a solid, reliable esc. With a 10A rating, the BotBitz 10A ESC is well suited for 1 and 3lb fighting robots. If you’re looking for advanced features you’ll have to look elsewhere for now, but if you want a bare bones ESC in a compact, easy to use package the BotBitz 10A esc is a strong contender.
Name: BotBitz 85A ESC
Specs:
Voltage- 6V – 24V
Current- 85A (1 minute)
Dimensions- 2.58 x 1.34 x 0.69 inches
Weight- 80g
Cost- $75.00 AUD
Comments- This is the larger of the BotBitz reprogrammed ESCs. With an absolute 200A maximum and testing proving that it can handle 85A for a full minute without melting or catching fire the BotBitz 10A esc is a strong contender in the 12 and 30lb classes if you’re looking for a bare bones controller.
Name: Holmes Hobbies BR-XL
Specs:
Voltage- 6V – 25V (2-6s lipo)
Current- 80A continuous
Dimensions- 1.97 x 1.54 x 0.83 inches
Weight- 45.6g
Cost-$99.99
Features- BEC, regenerative brake, active hold brake, castle link programmable
Comments- The BR-XL is the least robotics specific ESC presented. These controllers were originally made for high powered RC rock crawlers. The features that were needed for high powered rock crawlers happened to closely match the needs of 12-30lb fighting robots and over the last few years these have seen widespread use. Unlike many RC car ESCs the BR-XL actually appears to live up to the published specs and has been used in the drive system on 30lb fighting robots with high powered drive systems. These ESCs are durable, compact, and easy to use. For a 12-30lb robot these ESCs are certainly worth putting on the short list of options. Holmes Hobbies has also recently released a BR Mini rated for 30A continuous and 80A peak with otherwise similar functionality and specs at a price of $69.99. They look promising but I have not yet seen them in use in a robotic combat application.
Name: Equals Zero Designs Ragebridge
Specs:
Voltage- 12V – 36V, 50V absolute limit
Current- 30A continuous, 90A peak with limiting
Dimensions- 4.5 x 2.0 x 0.5”
Weight- 99g
Cost- $185.00
Features- Adjustable current limiting, channel mixing, flip control, regenerative braking, BEC
Comments- The Ragebridge is one of the newer ESCs on the market and it has quickly gained popularity. The biggest feature on the Ragebridge is the adjustable current limit. This feature allows you to tweak the performance of the ESC to balance pure power vs. reliability. This also reduces stress on motors and batteries, as when they’re limited you’re never pulling the sometimes massive peak current loads while still getting the vast majority of the usable power band of the motor. Whether it’s due to the way the regenerative braking code is written or just an aspect of how throttle ramping is handled, the Ragebridge also has an extremely smooth throttle response. For the 12 and 30lb class the Ragebridge is a fantastic motor controller option and should be considered in most applications.
Name: Sabertooth 25 Dual Motor Controller
Specs:
Voltage- 6V – 30V
Current- 25A continuous, 50A peak
Dimensions- 2.6 x 3.2 x 0.8 inches
Weight- 96g
Cost- $130.99
Features- Regenerative braking, current and overtemp protection, lipo protection mode
Comments- The Sabertooth 25 is a versatile controller with many options for inputs and dip switches that allow a range of parameters to be quickly and easily changed. While versatile, the Sabertooth 25 is fragile and a common recommendation is to coat it in a thick silicone adhesive (shoe goo and goop are common options) and to shock mount it to reduce the risk of shock induced failure. If you don’t expect high shock loads in your application and you need the versatility the Sabertooth offers it’s worth considering.
Name: Robot Power Scorpion XL
Specs:
Voltage- 4.8V – 28V
Current- 12.5A continuous, 45A peak
Dimensions- 2.7 x 1.6 x 0.5 inches
Weight- 28g
Cost- $104.99
Features- Current and overtemp limiting, dual channel, flip control, channel mixing
Comments- The Scorpion XL is the smallest dual channel esc intended for 12lb robots. With the low continuous current rating this controller is best suited to weaponed robots with mid to low powered drive systems if it is being used in the 12lb class. The small size also means it is possible to put it into something as small as a 1lb robot, however trying to use it in anything below the 3lb class is excessive, and in the case of a 3lb bot it would be best suited to a rammer or wedge with a very demanding drive system. The small size and light weight makes it a good candidate for 12lb robots that are tight on both space and weight.
Name: Robot Power Scorpion XXL
Specs:
Voltage- 6.0V – 28V
Current- 20A continuous, 45A peak
Dimensions- 3.27 x 2.27 x 0.5 inches
Weight- 52g
Cost- $159.99
Features- Current and overtemp limiting, dual channel, flip control, channel mixing
Comments- The Scorpion XXL is the larger cousin of the Scorpion XL. With the increased weight, size, and current limit this controller would pair well with many 12lb drive systems and may be capable of running lower powered or weapon focused 30lb drive systems. The small size and light weight make it easy to fit into 12 and 30lb robots that are tight on space and weight.
Name: FingerTech Robotics TinyESC
Specs:
Voltage- 6.5V – 36V
Current- 2A continuous, 3A peak
Dimensions- 0.53 x 0.90 x 0.19 inches
Weight- 4.5g
Cost- $33.99
Features- Undervoltage protection, overcurrent/temp protection, BEC.
Comments- The FingerTech TinyESC is in effect the default controller for the 150g and 1lb classes. Its small size, light weight, and wide voltage range make it a great option for most robots in those classes. The TinyESC has also seen use in the 3lb class, though it hasn’t gained the same grip on the 3lb class as it has in the 150g and 1lb classes. The TinyESC has been tested and is proven to work with some of the common drive motors used in 3lb robots, though it is suggested that you solder the included 0.01uF capacitor between the motor leads when using TinyESCs in a 3lb bot. These ESCs are tiny, highly reliable, and offer smooth control. If you’re building an insect class robot these should be on the short list of ESC options.
Name: Vex ESC (modified)
Specs:
Voltage- 8.5V official, 14.8V reported
Current- 3A official
Dimensions – 0.6 x 1.1 x 0.21 inches without case
Cost- $9.99
Features- Modifiable
Comments- The Vex ESC is an odd case, in that you have to modify the controller to get the most out of it. When properly modified the Vex ESC is a highly capable ESC for the 1-3lb classes. The modified Vex ESCs have been gaining in popularity and recently have become available pre-modified through TitanTechIndustries.com for $19.99. If you’re looking for a cheap, compact, no frills ESC for the 1-3lb class the modified Vex ESC is a solid option.
Special Notes- Modification documentation is available at http://thevariableconstant.blogspot.com/...
Name: Robot Power Wasp
Specs:
Voltage- 6.5V - 28V
Current- 10A continuous, 30A peak
Dimensions- 0.65 x 1.85 x 0.44 inches
Weight- 9.0g
Cost- $69.99
Features- Full current limiting and over temp limiting, limit switch inputs, BEC if used at or below 18v.
Comments- The Wasp is a compact single channel ESC from the same company that makes the Scorption XL and XXL. The Wasp is best suited for use in 3-12lb robots, though due to its small size caution must be used when attempting to use it in a 12lb robot as many common 12lb drive solutions can stall well in excess of the 30A limit. While you may not fry the controller the overtemp protection may result in the robot stopping in the middle of a match if you spend too much time near the current limit.