"Poor man's" DIY Buwizz (rc airplane liPo + Sbrick)

[Marxpek]

Here is something i created to test if it is worth it for me to buy a buwizz.

 

The s-brick has a brick built case around it, to replicate the Buwizz design.

The battery is a 7.4v LiPo ) i had this in the attic from my abandoned rc plane hobby.

THIS THING IS DANGEROUS! sorry for the caps but really do not do this unless you are sure what you are doing, shorting or puncturing batteries like these can start a fire instantly, this one can deliver 34 amps, wich is insane (about 10 buggy motors) and never needed in Lego just in rc plane motors.

Nothing was modified, not even the battery, the battery wires are just wedged between a regular plate and a 2x8 lead plate, taped to the LiPo.

So this basically replicates a buwizz on slow settings, i do not dare to hook up a 11,1v 3 cell LiPo to the sbrick, the sbrick can handle the 11 volts but the LiPo fully charged will deliver something like 12,6v not worth the risk to me.

This battery obviously has more amps then what the buwizz battery can deliver but the sbrick here is the weakest link, the buwizz will allow for more amps used and more importantly it will give that beloved 11 volt, which my creation lacks. 

My conclusion is: i want a buwizz..

[Permo]

I hooked up a Graupner 11.1V 2000mAh Lipo battery to two Lego V2 IR receivers.

This setup gives a whopping 70 Watts ready to push those motors.

 

 

[mocbuild101]

There are a few advantages to using this kind of setup...

• Can use multiple SBricks on one battery.
• Can have multiple LiPo batteries to switch over.
• Battery can be placed separately to SBricks.

I am wondering what your "creation" that needs 11v is though...

[Permo]

Probably something fast

The advantage of a LiPo battery is current, it will never go "meh" under load.

The advantage of 11.1V (nominal) is higher RPM at the motors.

But DIY solutions are not for the fainth harted, you really need to KNOW what you are doing, as with LiPo cells things can get very dangerous when mishandling them.

Here's how I did mine;

I connected the Lego connectors to the XC60 LiPo connector using the outer wires only !... for safety !

Connecting the outer wires only means that no Lego motors and lights will run directly from the battery, there always needs to be an IR receiver in between, now the IR receiver has a current limiter inside (V2 has a limit of 3.5A with the Texas Instruments PWM chip) wich will protect your motorwindings from burning under severe load. Using two V2 receivers >> 2 x 3.5A x 11.1V = 77.7 Watts (nomimal)... that's a lot of power.

I'll purchase a 7.4V LiPo cell soon wich will result in a more 'normal' situation with the advantage of lot's of current.

I also ordered a little Voltmeter from China wich will be soldered to this contraption for the reason that you don't want to decharge your LiPo cells too much as they won't be able to charge anymore, so you always need to check your voltage and when the pack hits below 10V (3S 11.1V pack) means it's time to charge the battery.

Also never store fully charged LiPo cells, always store them at nominal level or slightly above that, I'd say 11.5V max so they won't catch fire on a hot summersday, as this is a chemical fire you won't be able to stop it once it goes haywire !

So if you don't KNOW this stuff allready stick with the BuWizz as it has electronics inside that protect the battery from over / under charge.

In general; DON'T BE STUPID !

 

[sirslayer]

@Permo

this might be a silly question, so youre saying your able to feed the IR receiver with 11.1 volts and youre not worried that the receiver could over heat?? is there a heat sink inside the IR receiver ?? I thought 10.4 volts is the max voltage to feed the IR receiver??   

[Permo]

I just boldly did it.... feeding it with a fully charged 12.6 Volts.

And it works fine... when I hook up 4 L motors to one IR receiver the current limiter kicks in, but splitting the load into two V2 receivers each feeding two L motors and one has the steering servo on the 2nd channel, no problems there.

Performance is stunning, oh my... I'll race any BuWizz and all you're going to see is my big bright taillights lol

Nothing runs hot or craps out.

Here's a video to see it in action; https://bricksafe.com/files/Permo/de-driftkikker/Video.mp4

I did not use a V1 receiver, it has a different make chip (850mW only)  and will shurely crap out, but on the V2's .... awesome !

Edited March 12, 2018 by Permo
Volts added

[sirslayer]

youre right i have found this link

http://www.plug.pt/forum/index.php?topic=5268.0

 

by the way, thats a nice looking model your sporting 

I wonder if the Lepin Rc receiver have any or at all some type of voltage input limitations?  

Edited March 12, 2018 by sirslayer
compliment

[Permo]

3 Fluke's and a scope,... that guy is a pro

I only have one Fluke and a scope.

I can't read spanish but here's the source I used to get some insights in Lego electronics; http://www.philohome.com/pfrec/pfrec.htm

[sirslayer]

Have you seen this video??  

 

[Permo]

Hahahaha.... that's crazy !!!

Too much modding for me... I figured the powersource is never Lego as it is either Duracell or Varta or Panasonic or BuWizz or whatever and I don't want to spend lots of money on batteries so I went for my LiPo solution wich only involves cutting some extension cables and some soldering.

I used the other ends of the cut in half extensioncable on a laser unit (ripped from a laserpointerpen) and a DIY LED string.

[mocbuild101]

4 hours ago, Permo said:

Here's how I did mine;

That's the same way I would have done it - splitting the power before it gets to the thin wires of the Lego cables 

[sirslayer]

Philohome website was very helpful and he was running his test motors @ 12 v !!  but dc direct connected, I've designed a simple generator by using 2 medium motors direct coupled to a Large motor which produced 3.5 volts from the pf connector  and only the large motor was power up from the receiver..  ill hook up the 2 x medium motor pf connector to some led lights and they would strobe. i wonder if its possible to use the generated 3.5 volts to a XL motors for a 9 volts plus 3.5 volt over drive?  

 

 

 

[Permo]

I don't think that would work as you would need to connect them in series, and Lego connectors are all paralel connections.

If cheap speed / mega torque is what you are looking for, a Lipo cell is the way to go.

I use this one; https://www.graupner.com/Power-Pack-LiPo-3S-/-2000-mAh-11-1-V-70-C-XT-60/78120.3/

With this charger / balancer; https://www.graupner.com/LiPo-Balancer-Charger-2-3S-for-10-18-V-DC-or-100-240-V-AC-for-XH-balancer-plugs/6454.XH/

And this cable; https://www.graupner.com/Charger-Cable-XT-60-D3-5/S8386/

Be cautious though, this stuff can be dangerous, 140 Amps is a lot of current !, you definitely don't want to short it ! ... I bet I can start my car on this battery fully charged !

 

 

[sirslayer]

Im almost done with my version of the poor man's , just add 1 AA 1.5 volts in series and see what happens 

[Permo]

Yes adding extra batteries should work... give you higher RPM.

[sirslayer]

boy , you just can't add 1.5 v without major surgery so I opted for this , Hosting is the Lego 8870 led lighting cable by splicing to my new 12 volt battery , The led lights will shine to let you know that your opponents will be eating your dust!!!!  

 

[Permo]

How about this ?

https://www.banggood.com/nl/DIY-12V-8-x-AA-Battery-Holder-Case-Box-With-Leads-Switch-p-998860.html?gmcCountry=NL&currency=EUR&createTmp=1&cur_warehouse=CN&utm_source=googleshopping&utm_medium=cpc_elc&utm_content=zouzou&utm_campaign=pla-nl-elc2-pc-nl&gclid=EAIaIQobChMI9t2HtNPn2QIVx53tCh3omQqIEAQYAyABEgJQd_D_BwE

 

[sirslayer]

it is flatter and it would be easy to install but the 12v black and decker battery is almost the same size and weight compared to the lego battery pack ,  just a tad bigger and its cheap!! 

https://www.ebay.com/i/273083889184?chn=ps&fl=a

Edited March 12, 2018 by sirslayer

[sirslayer]

I couldn't resist, The DIY Poor Man's ,Ultimately ghetto battery Mr. Lego  meet your replacement!!  Mr. Series The 12 volt wonder!! !

 

[Permo]

Oh my...

 

[mocbuild101]

That's one very long battery...

[Marxpek]

I see this is turning into a battery conversation and it already started people making unsafe constructions @sirslayer ... just get a battery holder for 8 aa batteries (or a 10 holder and use rechargeables).. even aa's can start a fire when used badly..

It was not my intention to making this a battery thread, there are plenty of them around.

The real buwizz arrived and i have been testing with a car that has a 20:28 (differential) gear reduction using the fast output from a buggy motor, driven by unimog wheels and a servo for steering, a pretty fast and fun setup, that demands a lot of current.  

My conclusion is that my DIY setup is comparable to the normal setting on the buwizz, not the slow like i initally guessed ( my Lipo always was fresh off the charger giving 8.4v) most likely after a while my DIY solution will run a bit slower due to voltage drop, while the buwizz most likely can regulate this better. 

Theoretically the buwizz can handle 3 buggy motors but i have not tried that yet, while the sbrick can only just handle 2 from my experience.

Buwizz was the winner at first glance and it seems to stay that way for now.

Edited March 14, 2018 by Marxpek

[recklessGlitch]

Ahah! If you really want a poor man's lego controll,
or just more possibilities than LEGO or buwizz or Sbrick offer
(for example wifi :P, not to mention bluetooth or autonomous programming)
just really do it yourself
for example, in my Batman Tumbler I use
an ESP-32 for controlling
2 Motors & 1 Servo (power functions)
4 independend lights,
powered by any rechargable 9-24 V battery.
That hardware costs about
30,- € kaching! :D

more technical details on my blog: https://benjaminkiesewetter.de/private/lego-tumbler-rc-motorization/

Edited March 1, 2021 by recklessGlitch

[FriedlS]

9 minutes ago, recklessGlitch said:

Ahah! If you really want a poor man's lego controll, or just more possibilities than LEGO or buwizz or Sbrick offer (for example wifi :P, not to mention bluetooth or autonomous programming)
just really do it yourself:
for example, in my Batman Tumbler I use an ESP-32 for controlling 2 Motors & 1 Servo (power functions) 4 independend lights, powered by any rechargable 9-24 V battery.
That hardware costs about
30,- € kaching! :D

more technical details on my blog: https://benjaminkiesewetter.de/private/lego-tumbler-rc-motorization/

Wow, great work! I guess you have a lot of fun to drive ist :)

But i think it will be better with real rc components for controlling it.

I use this one in my Lego modells:

RC Components by Friedl St, auf Flickr

or something like that with brushless motor:

https://www.youtube.com/embed/v5Ey2yWuErM?feature=oembed

 

[Milan]

@recklessGlitch Let's try to use normal fonts and keep posts easily readable.

@FriedlS Let's not quote the whole block of text and pictures from the previous post.

Thanks.