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I have two buggy motors, 5292 like this:

buggy motor

I see powering each separately and using two IR receivers soon triggers the receivers' protections and the motors are stopped.

My aim is not speed, I see battery options powering with 7.2-7.5V instead of others powering with 9V, obviously the latter ones performs faster, but I try to have a safely working setup, without burning components.

Lego IR receiver

What is the best way to power up them? Is there a way to avoid using Android apps and bluetooth, or EV3 stuff, by using an IR setup at all? Is it possible to avoid SBicks and BuWizz? If not, are these reliable? I see people talking about LiPo instability. Is it that fire-hazardous?

Having in mind that Lego has overheat protections that often stop the motors on load, first question would be: is there a setup with Lego's LiPo battery to avoid the known hiccups behavior, without bypassing the protections?

Lego LiPo battery

And I have a side question: how to control a buggy motor using its box 54734, that come together in the 8287 set, with an IR Receiver? Mine simply does not power up the IR. I've tried all Lego Power Functions extension cables, the IR receiver doesn't lit.

54734 Lego battery box

Update

I have a RC power unit now:

6272c01

A thing that nobody tells ~ and I've searched a lot ~ is that steering goes 45°, unlike the servo motor that goes for 90°.

Servo motor

Building big means heavy (I try the agrof's class 1 buggy), so I've used multiplication twice in order to achieve the same 90° with the RC unit. This powered down the steering so it could not work when not running. A crackling sound is heard from it too, when tried. The multiplication is like this:

20T12T20T12T

agrof's steering is pretty complicated to change in order to use a 20T instead of 12T due to the steering wishbones and link positioning, as the 20T is bigger in diameter. Also, don't know if it is enough.

wishbone link

Now, similar to Michael Verschaeve's idea, the 45° steering could be used to action a switch in order to steer using a servo motor, but seems pretty weird to me.

8869

  • 1
    Can you show some links to what others have tried and tested? – Aziraphale Feb 15 '18 at 20:20
  • 1
    Here: 1. Philo's video; 2. Philo's full article; 3. Sariel's. – mike Feb 15 '18 at 21:23
  • In my experience, the hickups occur in about 30 seconds, all parts are new (I've unsealed them myself...). Each motor has its own receiver. – mike Feb 15 '18 at 21:25
  • Perhaps get a hold of the RC units that came with the buggy? Afterall, those were designed for it ... – Michael Verschaeve Feb 16 '18 at 9:57
  • The buggy motor comes in a set , 8287, having no remote or receiver. – mike Feb 16 '18 at 10:25
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The Lipo, thermal protections kicks in when consuming about 1A, while the buggy motor will consume 1.3 A when loaded but not stalled. So for two buggy motors, best would be 3 lipo's in parallel but perhaps you can get away with 2. The V1 receiver, only 850 mA before the protection kicks in, so not enough to power 1 buggy motor, let alone 2. The V2 receiver, 1.5 A before the protection kicks in, enough to power 1 buggy motor...

What might be a solution is having the V1 receiver control a medium motor or servo which mechanically switches a 8869 control switch which in turn switches the buggys on and off...

As for the old battery box, I think the reason you don't get it to power a V1 receiver is because power functions have two pairs of wires, a control pair and a pair that gives a constant voltage.

M,L and XL motors only use the control pairs of wires.

A servo uses the voltage pair to keep its position and the control pair to determine the position.

A receiver uses the input voltage pair to power itself, ignores the input control pair, forwards the voltage pair to the output voltage pairs and places control voltage on the output control pairs as it's instructed by the remote.

When using PF to 9V conversion cables, I think only the control pairs get connected, never the voltage pairs so the receivers cannot be powered by 9V battery boxes or cables...

  • Good information, but I've read that using V2 receiver and a 8881 battery box will trigger the box protection, so it will stop the buggy attached eventually (presuming one box per motor is set, for testing reasons). The original buggy receiver would be better? What would be the drawbacks? – mike Feb 19 '18 at 14:55
  • The buggy receiver drawbacks, shape and size might be a bit inconvenient. Main drawback will be the availability, they are hard to find in good condition and hence costly... – Michael Verschaeve Feb 19 '18 at 16:03
  • Actually I have one. But the true drawback is the steering. It goes 45 degrees only, compared to the servo motor which goes 90 degrees. Multiplication twice gains the degrees, but loses to much power and works when running only. My actual design makes things really complicated to change (see argof's class 1 buggy for reference), as a bigger tooth gear being problematic. – mike Mar 11 '18 at 17:57
  • I think it would be better if you start a new question regarding the steering with buggies. Now this thread is getting a bit convoluted in my opinion – Michael Verschaeve Mar 12 '18 at 8:42
  • I think that too, still, when powering with the RC version, the steering comes built in, so people should know what they get, that being not optional. – mike Mar 12 '18 at 18:11

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