legomen

Thanks. Yeah, this why I am now working also on my own battery, although Buwizz should have enough power to drive it.

And here is the test rig for the first prototype. I have used this rig to test Lego L motor and compare the speed with Brushless L motor. Later is more then twice the speed. The bottleneck here is the battery. Because of the voltage drop, the motor has only 6V to work with. Need to try it with Buwizz at 11V. That will most surely speed things up. I have decided to design a NEW battery system to be used with my brushless motors. It is in the working:)

It is using standard PF PWM signal to define desired RPM (in both directions). 100% duty cycle means highest rpm and 0% is stop. PF has two signals, one for each direction. The ESC is using FOC algorithm in order to maximize efficency at every RPM. From theory of FOC, the most problematic is startup, because the motor is sensorless and FOC can not estimate the proper rotor angle. For that ESC is using different technique to start the motor and once it is started it switches to FOC. Motor assembly with Kyosho XSpeed41. Expensive, but very high quality motor. and fresh ESCs.

It is in prototype stage. I am testing it with two different motors. 3500KV and 4100KV. Motor can draw up to 5A, but this are short spikes. Normally, it draws far less current. I do not think the wires are a problem. Also did not notice connector troubles. Motor with an ESC.

L Motor with brushless motor and integrated ESC. The motor uses existing L Motor housing and PF connector. It can be connected and controlled with existing batteries, like Buwizz or even Lego.

Exactly. M motor is much more forgivable when building, although L motor could be better fixed, due to rear stud holes. I think my ESC could also fit into M motor, but space there is much more limiting. I really do not like those phone apps to control Lego stuff. It is always giving me problems when connecting. I have two SBricks (now you know what I am talking about:)). And is also slow as hell. Haven't try connecting it with Joystick. I would say addtional delay between control and action. This why I am looking to design a battery system where controller will connect directly to a Joystick console, like DualSense or XBox. Regarding the servo action, I was thinking to use brushless motor also for servo, but things are not so easy if you don't have angular position sensor. I could make an ESC board with that, but then the whole housing should be newly designed as well. And from work, I can tell you, mechanics is not cheap:)

Thanks. That is the inrunner. I am not arguing anything:) I am only stating my opinion regarding the use of RC stuff in Lego world. I understand the speed and power from RC world is impressive. I own ARRMA Typhon 3S and I can tell you it can fly, literally:) But Lego Technic needs its own stuff. For example, PU L motor is great addition, because old PF servos (originals) are expensive as hell and fake ones are not steering as they should. With PU steering things could be much more precise. For the propulsion, yes they are faster brushed motors available, but they make annoying sounds and are not as efficient at low speeds. Brushless is quiet, and you can control them efficiently even at low speeds. They have their own quirks, like starting, but with proper control even that is managable. Even sensoreds motors are not out of reach. What I wanted to say is that making the Lego Motor with brushless motor inside is addition to already established motor lineup (from Lego or some others). Imagine, what can be done with brushless motor inside Buggy motor. You could have twice the speed and with proper motor also torque. The limiting factor here is the battery. I know it is easy to put a LiPo from RC in a model, but it is not the point here. When I was designing the motor itself, I have deliberately choose one of the smaller brushless motors out there, first to put it in into existent L motor housing and second not to make it too powerful, because otherwise it will brake (plastic)things easily. What is the fun of that (I can bash away with Typhon 3S easily a few hundred euros:))). For those who want raw power, RC motors and ESCs and 3D printed metallic parts are the way, but not for the purists. Here is also a picture of assembled motor and ESC (without gearbox and casing): BTW, impressive stuff you have there on other threads. Congrats.

The model on the previous picture has 4100KV motor built in. On 9V, the motor is spinning up to 1400RPM (after 1:26 planetary gearbox of course) without load. I have tested it with standard Lego AA battery box, with resetable fuse removed. Compared to ordinary L motor, it has more then twice the speed under load. I have not tested it with Buwizz 3.0, yet. I have decided to design a new battery controller to be used with my motors. This perticualr brushless motor can spike up to 8A when stalled, although I did not see this kind of troubles when testing my motor. But nevertheless, a new battery is needed tu support at least two motors or more. I have designed and built the ESC myself. It is Field Oriented Control ESC, with Lego PF signals controlling the speed of a motor. It has all needed protections integrated (overcurrent, temperature, ...). Yes, I saw some of Chinese ESC with simple trapezodial algorithm, but they are still to big to be used inside L motor and I have took on a challenge to develop my own. It was quite a ride:) The point was to made a better L motor, which is still fully Lego (interface wise) interoperable. I have seen mixing of Lego and RC and honestly I think it is not the right way. RC is on another level of speed and control, but Lego is something different, although some more speed and fun would be appreciated. Although Lego is upgrading its motors, they are still pretty much to slow to drive larger and more complicated MOCs. We have many official Lego models and even MOCs and my kids are always complaining about speed and control. The most enjoyable model for my kids is 42065 with simple IR controller and it is quite fast, but still underpowered. IMHO new control apps on Android or Iphone are not that good. My little one preffer IR transmitter over phone anytime. This why I have took on a challenge to make something better. Maybe a new thread to discuss this new world?

I have developed my own brushless motor with integrated ESC. It has a standard PF connector. Yes, one could use RC ESC and battery, but that somehow seems wrong in the Lego world:)

I come from the RC world, where LiPo cells could swell considerably when pushing them too far. Reading the battery manufacturer specification where around 1A current is maximum gives me little confidence. I am experimenting with brushless motors, where high current spikes could damge the whole thing.

Looking to Buwizz 3.0 battery replacement video, it seem they are using something like HPL502852-5C-3S1P 800mAh battery, which has a specified continuous discharge current rated to 1C. That means only 0.8A. Four amps per channel are far from that specified value. Wondering about safety.

Greyhound can be driven with single Lego battery box (Eneloop Pro batteries installed), but PTC resistor must be shorted, although lacking torque on wheels. We really need better L motors:)

I was also thinking that, but needed to be sure:) Yes, I would like to buy 1 Buwizz as a battery and use additional SBrick to have all 7 ports available. I actually need 6 ports for Greyhound. Would one Buwizz be enough? Originally Greyhound is using two of them, one for two L motors.

Does Buwizz 2.0 provide constant voltage (up to 11V) on voltage supply pins or does it only provide PWMed voltage on C1/C2 only? I own SBricks only, but prior to buying Buwizz to use it also for powering SBrick, I'd like to be sure it is possible. Thanks.

More pictures with Lego battery box placing. I needed to redesign whole back end of a chassis in order to make space for Lego 8881 battery. V8 motor shifted more to the back and M motor connection completely redesigned. Battery box is fixed in place with two pins and relative easily removed from the car. Still looking for new springs:) https://photos.app.goo.gl/tPvpn1i5pYFmEdwq6 PS: Probably PTC resistor would need to be removed from the battery box.

My implementation of Greyhound 4x4. With standard Lego battery box and 2 SBricks.