Buwizz 3.0 Pro Current Limit?

[Silicon]

Hi all, 

Im using the buwizz 3.0 pro with buwizz motors for a Technic MOC. I noticed that the claimed power output is 48w per PF port with max continuous power of 4A. 

However, in the buwizz app it defaults to 2A per port with a warning of exceeding this could overload the battery. The max current you can also set the battery to is only 3.5A.

Am i missing something?

P=IV so assuming 11V ish with 2A i get 22w per motor not 48W?

Id like to be able to utilise the full 48W continuously.

Thanks in advance!

[Zerobricks]

In such case I recommend drawing power from both ports (2A each) in order not to literally melt them.

[Silicon]

Tech specs from BuWizz is 4A PER channel, not combined. 
 

trying to use the full 96w continuous power I should be able to generate from two PF ports being used. 

[Zerobricks]

The battery has a 7A lsafety imit, so the theoretical max constant power you can get is 84 Watts. I would not recommend pulling more than 2A constantly from the PF ports, as they might melt due to the contact resistance, PU ports are better for such cases due to the larger contact surface.

[Silicon]

That’s useful information but then I don’t understand why BuWizz advertises 96w and continuous 4A per port then when this is completely incorrect. You can only generate half the power they are claimed to provide.

 

 

Edited May 13, 2024 by Silicon

[legomen]

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.

[Aurorasaurus]

1 hour ago, legomen said:

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.

Ive pushed my buwizz 3.0s incredibly hard, even running them connected to battery banks to avoid current shut downs. Never had any issues with melting things or fires, the unit has built in protections. Also, I really doubt you'd ever get 4a from a buwizz unit at 12v as it cuts out well before then.

[legomen]

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. 

[gyenesvi]

5 hours ago, legomen said:

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.

I think that is exactly why Buwizz 3.0 units are shutting down if you push them hard, which is quite easy to achieve using 2 Buwizz motors and moderately high gearing ratio (not enough down-gearing).

2 hours ago, legomen said:

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. 

For brushless motors, I assume you must be using a brushless ESC as well, and probably an RC receiver? Then why would you need a Buwizz in your system? With a proper RC battery, it should be fine, that's what I use.

[legomen]

2 hours ago, gyenesvi said:

I think that is exactly why Buwizz 3.0 units are shutting down if you push them hard, which is quite easy to achieve using 2 Buwizz motors and moderately high gearing ratio (not enough down-gearing).

For brushless motors, I assume you must be using a brushless ESC as well, and probably an RC receiver? Then why would you need a Buwizz in your system? With a proper RC battery, it should be fine, that's what I use.

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:)

[gyenesvi]

4 hours ago, legomen said:

I have developed my own brushless motor with integrated ESC. It has a standard PF connector.

That sounds interesting, can you share more details about it? What kind of brushless motor? Did you design the ESC, or is it something off the shelf? I saw such brushless motors with integrated ESC do exist on the market, is it one of those maybe?

I suppose it works with standard PF control signals?

4 hours ago, legomen said:

Yes, one could use RC ESC and battery, but that somehow seems wrong in the Lego world:)

Well, you are already using custom made motor and ESC, so..

By the way, you'll also need precise steering for the speeds that such a motor provides, and that will also be a challenge with a Buwizz unit and Lego servos..

[legomen]

7 hours ago, gyenesvi said:

That sounds interesting, can you share more details about it? What kind of brushless motor? Did you design the ESC, or is it something off the shelf? I saw such brushless motors with integrated ESC do exist on the market, is it one of those maybe?

I suppose it works with standard PF control signals?

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:)

7 hours ago, gyenesvi said:

Well, you are already using custom made motor and ESC, so..

By the way, you'll also need precise steering for the speeds that such a motor provides, and that will also be a challenge with a Buwizz unit and Lego servos..

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?

 

[gyenesvi]

2 hours ago, legomen said:

I have designed and built the ESC myself.

2 hours ago, legomen said:

I have decided to design a new battery controller to be used with my motors.

That is pretty impressive, cool that you have the skill to do that, I could really use such knowledge myself. I only got to the point of building my lego compatible brushless electronics from off-the shelf components and 3d printed casings. But the experience is already a huge leap from basic lego electronics:

https://www.eurobricks.com/forum/forums/topic/209870-wip-small-scale-defender-with-brushless-motor-pure-lego-alternative/

2 hours ago, legomen said:

The model on the previous picture has 4100KV motor built in.

Is that an inrunner or an outrunner motor?

2 hours ago, legomen said:

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.

I'm not sure I understand what you are arguing against here. Is it the mixing of the two types of electronics, or is it using brushless in lego altogether? Since you are doing the second one anyway, I am bit confused.

Anyways, to achieve the single goal of having a better L motor in a lego compatible way, there's another, maybe easier path. The (brushed) motor inside the old lego buggy motor (or the Buwizz motor) is the same size as the one inside the L motor, but more powerful, so you can swap that inside the L motor housing (you can buy some 3d party buggy motor clones, or some buwizz motors  for acquiring the motor itself). That gives you about 2,5x - 3x more power according to my measurements, and you can connect two of those to a Buwizz 3; plenty of power with good speed / torque ratio for lego.

I have a few MOCs that use such modified L motors (though I didn't make the motors myself). Those MOCs use brushed RC ESC for control, but that is not strictly necessary, I used it to be able to use proper servos and a pistol grip transmitter.

https://www.eurobricks.com/forum/forums/topic/200233-moc-toyota-hilux-truggy-rc-18-scale-with-custom-electronics/

https://www.eurobricks.com/forum/forums/topic/211649-moc-rock-crawler-jesse-haines-moon-buggy-with-rc-electronics/

2 hours ago, legomen said:

Maybe a new thread to discuss this new world?

There is already a thread for brushless motors in lego, so you could re-post this motor design there, I'm sure folks would be pretty interested.

https://www.eurobricks.com/forum/forums/topic/194125-brushless-motors-in-the-lego-world-general-topic/

[legomen]

16 minutes ago, gyenesvi said:

Is that an inrunner or an outrunner motor?

Thanks. That is the inrunner.

20 minutes ago, gyenesvi said:

I'm not sure I understand what you are arguing against here. Is it the mixing of the two types of electronics, or is it using brushless in lego altogether? Since you are doing the second one anyway, I am bit confused.

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.

[gyenesvi]

15 minutes ago, legomen said:

I am not arguing anything:) I am only stating my opinion regarding the use of RC stuff in Lego world.

Okay, by arguing I just meant what your view is on the matter :)

20 minutes ago, legomen said:

What I wanted to say is that making the Lego Motor with brushless motor inside is addition to already established motor lineup

That makes sense.

15 minutes ago, legomen said:

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.

17 minutes ago, legomen said:

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.

Yes, I totally agree, that is exactly the reason why I also started looking into brushless systems, and the same way, I aimed for the smallest one I could easily get. I am more interested in precise control than very high speeds that can damage lego parts. Although, with better steering, higher speeds also become more enjoyable :)

20 minutes ago, legomen said:

Imagine, what can be done with brushless motor inside Buggy motor.

Unfortunately, I really don't like the form factor of the buggy motor, I find it hard to integrate into smaller or even medium MOCs in a way to preserve space for other stuff like suspension.

Even the form factor of the L motor could be improved if the motor inside would allow, like the one you have there. Those half stud bumps on the sides of the L motor are really annoying, they are always in the way for something (like a driveshaft running next to the motor). A motor with a 3x3 cross section (like an M motor) would be achievable and would have significant advantage for smaller builds.

23 minutes ago, legomen said:

With PU steering things could be much more precise.

Unfortunately, that's not my experience with basic bluetooth control, even using an Xbox controller. I think the method of measuring position / moving the motor is just too slow. I only felt it after having tried lego compatible GeekServos, they are night and day in terms of precision. Actually, just using a Buwizz and an Xbox controller, the old PF servos felt a little more precise than PU ones for me.

Or do you mean they could be made more precise using some other control mechanism, like a custom circuit?

[legomen]

2 minutes ago, gyenesvi said:

Even the form factor of the L motor could be improved if the motor inside would allow, like the one you have there. Those half stud bumps on the sides of the L motor are really annoying, they are always in the way for something (like a driveshaft running next to the motor). A motor with a 3x3 cross section (like an M motor) would be achievable and would have significant advantage for smaller builds.

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.

 

4 minutes ago, gyenesvi said:

Unfortunately, that's not my experience with basic bluetooth control, even using an Xbox controller. I think the method of measuring position / moving the motor is just too slow. I only felt it after having tried lego compatible GeekServos, they are night and day in terms of precision. Actually, just using a Buwizz and an Xbox controller, the old PF servos felt a little more precise than PU ones for me.

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:)