The Betaflight BLHeli_32 35A ESC is a cutting-edge ESC offering just about every feature that’s available today. Thanks to FPVModel, we have a set for review.

Features

It’s obvious that a vast feature set was a design goal here:

  • 32-bit processor with BLHeli_32 firmware
  • 2–6S Lipo input
  • 35A (burst at 45+)
  • Supports almost all known ESC protocols, notably DSHOT1200
  • 32kHz input data rate/update speed (with DSHOT1200)
  • 48kHz motor output frequency (2048 steps)
  • Filtering capacitors
  • Automatic timing
  • Self-protection features, including voltage and current limiting
  • ESC Telemetry: Voltage, current, temperature, and RPM
  • DSHOT commands (Anti-turtle mode, using motor as buzzer, etc.)
  • Customizable LED

Included in each package is the ESC itself and a selection of 10cm wires: a red and a black 16AWG, three black 20AWG, and a red 26AWG. We’d prefer a red/black pair of 16AWG (battery/ground), a pair of white/black 20AWG (ESC signal/ground), and an alternate color 26AWG (telemetry).

Electronics

A large bus bar delivers current across the board. Don’t let this (or anything else) short to your carbon frame.

The ESCs did not appear to have any problems with component placement or soldering. The commitment to speed and performance is visible right on the board with prominent features like large capacitors, a protection diode, and a bus bar. These ESCs don’t offer a BEC, but many modern components such as flight controllers, cameras, and VTx accept full battery voltage now and provide regulated power. The board is offered bare—the user must solder all of the connecting wires and add any heat shrink or other protection. You definitely need to add protection of some sort, because placing this directly on a carbon frame might short out some of the components. Other ESCs sometimes have a large heat sink. The Betaflight ESC doesn’t appear to need one, but that also means it isn’t offering protection to the components underneath.

The Betaflight ESC is not small. At 34×16×7mm and 6g, That’s considerably larger and heavier than many “performance” ESCs generally weighing less than four. Taller components are clustered on one side of the board, making for a product that doesn’t sit flat. The onboard LED on the top side is very bright. I expected it to be used for status, but I’ve only noticed it blink very briefly at power up or power down. Otherwise, it stays off unless you’ve configured it to be on. If you decide to use opaque heat shrink to protect the ESC, you’ll cover up the LED.

Installation

The telemetry pad is only about the size of the letters on a US penny and requires advanced soldering skill. I’m fairly experienced at soldering, and I still botched this one.

The size may be an issue on smaller frames. On the Hyperlite FLOSS 2, the ESC is very difficult to fit on the arm. I ended up offsetting it back somewhat. This isn’t a particularly solid mounting and might prove to have issues over the long term.

The board offers top and bottom pads for power, signal, and motor connections. Solder pads for power are large and generous, pads for the motors are acceptable, and pads for the signal are somewhat small. The pads sometimes run around the outside edge of the FC. This last feature complicated the soldering for me; as I was adding solder to the pad on one board, it flowed around to the underside instead of building up where I wanted it. Signal pads are a little difficult to solder to. By making the power pads so massive and solder-friendly, the signal pads suffered—as a result, the ESC isn’t really any easier than many others to get hooked up. Motor pads are sized just about right, but seem to be really tight to other components on the board. I was a little concerned that I might accidentally heat and move a board component, but I didn’t actually have an issue here.

The telemetry pad is extremely small, awkwardly placed, and very close to other components. If you’re not skilled with soldering, you probably shouldn’t attempt to connect to it yourself. I don’t understand the design decision here, especially as a feature that is a main selling point. You really want a small-gauge wire for this—the extra black 20AWG is a bit too large for the job. If you do solder for telemetry, protect this part of the board with some glue afterward. The pads here come off the board under very little stress.

To take full advantage of the ESC’s features, you really need to be running Betaflight 3.2 or greater on your flight controller. Get started with Betaflight using our configuration guide.

Configuration

The board is widely populated with components, some very close to motor outputs—but somehow there’s enough room for a Betaflight logo.

Simply getting the ESCs into the air is simple. Connect the power and signal wires, then make a trip into Betaflight. Most likely you’ll only purchase these ESCs for their high-end capability, so hit the Configuration tab and select DSHOT1200 or whatever the highest DSHOT value is that your flight controller supports. DSHOT will handle calibration and you’re ready to take off.

If you want to get deeper into its configuration, you’ll need to download the latest version of BLHeli Suite. Using a flight controller and Betaflight version that supports ESC passthrough, you can configure them while connected to the quad and don’t need any special connection equipment. As of this writing, the BLHeli Configurator chrome app will not work, but we expect that to change soon.

Most of the settings are highly technical and, frankly, don’t need messed with at all. Many options carry over from previous versions of BLHeli, so take a look at our BLHeli configuration guide if they’re not familiar to you. You can also dive into the BLHeli_32 manual for in-depth descriptions of each. Most users only need to consider a select few of the options. There are a number of protection settings. The voltage limiter can protect your battery from over-discharge, but if you hit it you’ll just fall out of the sky. The current limiter can protect the motor and ESC, but will limit your top-end throttle and might affect your control authority. These ESCs have temperature protection and low RPM power protect, so they won’t overheat or keep pumping in current if the motor isn’t moving. With each of these features installed, hopefully you can avoid burning them out.

For the LED, you can select each channel (red, green, and blue) to be on or off. Mix these for one of 7 color choices: red, green, blue, yellow, cyan, magenta, or white. You can only illuminate a channel fully, so partial-color options like pink or orange aren’t possible. You can’t change or assign functions to these LEDs from within Betaflight.

Telemetry

Size comparison, left to right: a 20A ESC off the Wizard X220, a Tattu 30A ESC, and the Betaflight ESC.

Once connected, you can have the ESCs feed telemetry data back to the flight controller. This provides voltage, current, temperature and rotational speed for each motor. As far as I could tell, there are only a few very limited ways to see the data. The ‘power’ panel in Betaflight will give you each ESC’s voltage and current reading if you’ve selected the ESCs as the data source. On the OSD, you can print the combined voltage, current, temperature, and RPM data. Blackbox logs don’t record anything except combined voltage and current, if you have your FC set up to use them as the primary source. This means that you can’t see the individual temperature or RPM readings anywhere, and all of this data is useless for analysis after the fact. It’s a pretty substantial disappointment and severely limits the value of having telemetry at all. This is a Betaflight issue, not a problem with the ESC—we hope a future version will unlock the potential that this hardware has.

In addition, the RPM and temperature data weren’t useful to me during flight either. I got some very strange readings, like negative RPM values and temperatures reading 99°C. I can’t fault the hardware on this one either—because of the installation difficulties, I only had three ESCs reporting. Betaflight appears to assume telemetry is always connected and working properly; it didn’t notify me that I wasn’t getting complete data.

The current sensors are set up to report the current that each motor is pulling. Because they are each measuring a smaller current, they can do it more accurately than a single sensor for the whole aircraft. This should give you a better reading, but divorces motor power usage from the rest of the system. The sensors don’t appear to report the ESC itself, as they still report 0.00A even with the LED turned on. The ESCs may not draw much, but ESC telemetry isn’t reporting on the current draw of your other components, either: FC, Camera, VTx, etc. For most people this will be a pretty small amount of power—consuming maybe 1% of your battery during a flight—but it’s worth remembering especially if you use a high-power video transmitter, multiple long LED strips, or other high-draw components. Since it doesn’t output the current draw of the whole quad, the accuracy benefit isn’t fully realized in flight. Recording only the motor’s power draw could still be useful as a data point in a log file, so we hope that will happen in a future Betaflight update.

Flight

I installed the Betaflight ESCs on an F7 board, allowing me to enable the full 32kHz looptime and sampling, but I started at 8kHz. During my first flight on 4S, one of my motors started acting up and made it very difficult to control. That issue passed after the first flight, and I assume the flight controller is at fault. Afterward, the flight was smooth and controlled—I had no complaints. I then wanted to change to 32kHz and see the difference. Before I was able to fly again, the F7 board died along with three of the ESCs.

Durability

I have to put a big question mark here. We couldn’t locate a probable cause for the F7 board’s failure. While we don’t think the ESCs killed the F7, it’s suspect that the three that died were those with the telemetry line connected. For all the protection features this ESC has for current, temperature, and voltage, it seems that this data line—directly connected to the board’s main logic chip—might be a vulnerability. Hopefully, flight controller failures like this one are rare and most won’t need robust protection on the data line. Since our review product died after only a few flights, we obviously can’t speak to the long-term reliability. I would have liked to find out if the protection features make ESC beepers and anti-turtle mode more safe to use, but I didn’t get that opportunity.

Conclusion

In my previous review of the Tattu BLHeli_S ESC, I wondered why that premium product would carry the BLHeli_S software instead of BLHeli_32. After reviewing the Betaflight ESC, I think I may have some answers. The Tattu ESC provides everything you need in a performance racer. They are lighter and considerably smaller than the Betaflight ESC—but almost an even match in flight performance (at least at 8k). The benefits of BLHeli_32 over BLHeli_S appear to be largely academic: telemetry data gives you really specific information about what’s happening with each motor, software provides extra protections from failure, and blazing data rates that might offer an incremental performance advantage—if your flight controller can support them. While there’s nothing wrong with any of that, when you include the extra size/weight, awkward form factor, complicated setup, and inability to access or log the telemetry data—the end result fails to inspire.

Make no mistake, the Betaflight ESC is a well-made product that can provide strong performance. It flies well and the added sensors can be a welcome addition for data heads or to a flight controller that doesn’t already have them. If you’re looking for an ESC with all of these features and can overlook the other challenges, it will be hard to go wrong with this on your quad. Perhaps a future update to Betaflight / Blackbox will allow us to realize its full potential.

 

 

 

 

 

 

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