Dual PF Battery Box Power Tutorial

[JamesJT]

I just tried adding the 9V battery to battery box and L-motor. It spins at the same speed but is much harder to stall. It only runs with the power switch on the PF box pushed towards the middle. I assume they cancel out/short circuit with the switch the other way.

(The L motor spins about 20% slower with the 9V PP3 battery compared to using the PF battery box)

[nerdsforprez]

@boxerlego - would it be possible to power two XL motors with the dual battery setup you got going here?

[nerdsforprez]

Anyone?

@Boxerlego.... where are you?

[nerdsforprez]

Since I have not been able to bend boxerlegos ear on this, I am bumping the topic. Does anyone know if this application can be applied to two xl motors, and not just one?

[Boxerlego]

Hi Everybody! The Truth is out there...

I just want to tell you that its critical for you to understand that according to modern Science standards about electricity this should never have work in the first place because after all Electrons travel from the Negative(-) to the Positive(+). Its also important to Understand that LEGO PF system is a 9v electrical system and the electrical components in the LEGO PF receiver are no way design to handle voltage up around 18V. So if there were 18Volts of electrons moving from the (-) Negative to the (+) Positive then the LEGO 9V electronics system would burn up. RIGHT!? Well that is what I thought too!! But I did the experiment anyway and found out otherwise.

It very Important to Understand that physics has taken over electricity and ultimately has come to the conclusion that this should never work and is bunk science. Ever hear of the Cathode Ray Tube Experiment of 1897 after all JJ Thompson is a important discoverer of the Electron and a big name in the modern electrical theory, Which I in fact have shown to everybody that he was wrong. Not impressed yet, I didn't think so.

I want to give a special Thanks To the LEGO corporation for their inhibition to recognize special talented people. Its been about four years already and still no Nobel prize for this discovery not even a Job offer to work for NASA or even CERN... supposed if I was a girl I would have been treated differently and probably would have been made a cultural Icon for all girls to look up to like madame curie showing those dumb boys a thing or two..

Remember if you don't promote talented minds you just going to end up living in a fools paradise so Enjoy your 70 virgins everybody! My next Project is going to be A Big Blast I'm thinking about building a Bomb that looks like LEGO Clock! So tell me what you think about my next Big project! Now that was a joke so if you don't understand my joke then surly you don't understand anything at in this point of time. Enjoy your Spring Break Everybody!

Edited March 10, 2016 by Jim
Made the post readable again

[Limga]

The truth is that it doubles the maximum current but not voltage, huh?:)

[Jim]

Hi Everybody! The Truth is out there...

...

Hi,

Not sure what to make of your post, but can you at least answer the question.

[nerdsforprez]

Hi,

Not sure what to make of your post, but can you at least answer the question.

+1

[Boxerlego]

The truth is that it doubles the maximum current but not voltage, huh?:)

If you want to increase the current just connect the PF wires normally. Just make sure all the batteries are the same voltage and the same type.

Hi,

Not sure what to make of your post, but can you at least answer the question.

Well the post is not about "what to make" but it is more along the lines about "not what to make". Because after all some could answer and say this is not safe to make especially the settled science physicists.

@boxerlego - would it be possible to power two XL motors with the dual battery setup you got going here?

I do know that there was a guy from japan that powered 4 rc motors, so yes It is possible to power two XL motors. For best effect keep the build light as possible.

[Technic Jim]

Hey Boxerlego. You mentioned in the first post about a resettable fuse. Sorry to be a but thick but where is this fuse nd how do you reset it if it has been tripped. Also, do the 5292 buggy motors have this fuse so would it be safe to use this setup with two of them and 12 rechargeable batteries.

Cheers!

[Boxerlego]

Hello there Technic Jim. The Fuse is self resetting, all you need to do is turn the power off and the fuse should reset itself after it has cooled down. I don't know if there is a resettable fuse in the 5292 buggy motors I never looked. However, you can power them on a acceptable range of voltage, I usually say 12volts is the limit but just remember that higher voltage on the motor means more deterioration it experiences. Some motors can run perfectly fine on 24 volts others might not do as well It just depends on the motor and the forces at work.

Edited March 12, 2016 by Boxerlego

[Brickthus]

Having seen this post a while ago, I decided to see how it would develop. The ideas are not without merit but need tempering with science in order to optimise safety and reliability.

It is quite possible to run any motor at a higher voltage than its rating, but you will shorten its life.

If you want to exceed the ratings to win a rally contest but replace your motors every so often then that's fine. In such contests, most of the parts are deemed expendable in pursuit of victory!

If you want to run the motors close to the fuse setting so that they trip occasionally then that's OK for you. However, a motor whose fuse has tripped will be more prone to tripping again because the fuse has a finite life.

For each motor that you intend to run beyond 9.15 Volts (the voltage of a set of fresh AA cells), do your research and find the industrial rating of the internal motor. If that says 12 volts then that particular motor type would be OK at 12 volts for a longer period. For most of the LEGO motors, provided the industrial rating is more than 9 Volts, I would recommend a maximum of 12 volts; I doubt very much whether the industrial rating is any higher than that for any LEGO motor type. You could achieve 12 volts by using 2x 1.5V cells and 4 dummy batteries in a second battery box. 4 cells and 2 dummies for rechargeable AAs whose full voltage is 1.2V.

At a higher voltage you will get more speed out of the motor because the speed is proportional to the voltage for a dc motor. If you have moderate duty cycle and make sure the motor does not get hot then you should be OK for a while.

For a dc motor with a commutator there are sparks generated as the contacts are made and broken. The higher the voltage, the stronger those sparks and the quicker the motor's life is used up.

The most efficient use of a dc motor is for it to run at half its no-load speed.

The IR Receivers contain motor drivers that are H-bridges with flywheel diodes. If you understand what's going on in the circuit as you use them then that's OK. You need to pass on the learning with the suggestion so that everyone understands what they are doing. Exceeding ratings without understanding just leads to product failure when you have invalidated the warranty.

TLG are good at replacing faulty parts but it's experiments like these that drive them to change the plug system. The backward compatibility of PF to 9V always left the system open to uses that TLG did not intend and could not possibly recommend for safety reasons. I still hope for some backward compatibility from the new plug system but it may be less likely because TLG need to meet the toy safety regulations and discourage connections outside their design intent.

I've done some electrical hacking myself and have burnt out a few motors in my time but these days I aim to maintain reliability with the results. When I use a bench power supply I tend to stick to 9.15 Volts as the maximum.

I have found the limit of PF train motors, which are currently the best source of power at high speed (except for obsolete 5292 motors). The experiment seeks to launch a Ninjago Airjitzu spinner from pure-LEGO electrical power. It could not quite launch with 2x PF M motors at 15:1 gearing up. 2x PF train motors and a freshly-charged LiPo battery did achieve a launch. A 5:1 gear-up ratio was good but a higher ratio than that did trip the motor fuses.

As someone who is prepared to experiment, you have potential as an engineer. LEGO and electronics kits are what guided me in that direction.

Despite the limitations on what a professional engineer can recommend, engineers know more and do get to over-rate things occasionally!

Mark

[rocklego]

For each motor that you intend to run beyond 9.15 Volts (the voltage of a set of fresh AA cells), do your research and find the industrial rating of the internal motor. If that says 12 volts then that particular motor type would be OK at 12 volts for a longer period. For most of the LEGO motors, provided the industrial rating is more than 9 Volts, I would recommend a maximum of 12 volts;

Mark

How are you so sure that industrial voltage rating for LEGO motors is more than 9 V ?

Do you have any prove like datasheets for internal motors ?

I just want to make sure not shortening the life of motors if supplying more voltage than 9 V.

[Technic Jim]

@Mark Bellis

Wow! Thanks a lot for your really helpful reply and everything else you mentioned

[morson1]

About connecting two battery boxes parallell: I´m building a vehicle with 5292 motor, and it stalls way to early. Been reading around whole day, but not sure anyway, so I ask for safety reasons... Is it possible and safe to connect two battery boxes in parallell to get more current? If so, can I power one receiver (V2) with those two boxes, or should I go for two separate "power units" each containing one box and one receiver (mating up at the motor)?

[Boxerlego]

Having seen this post a while ago, I decided to see how it would develop. The ideas are not without merit but need tempering with science in order to optimise safety and reliability.

It is quite possible to run any motor at a higher voltage than its rating, but you will shorten its life.

If you want to exceed the ratings to win a rally contest but replace your motors every so often then that's fine. In such contests, most of the parts are deemed expendable in pursuit of victory!

If you want to run the motors close to the fuse setting so that they trip occasionally then that's OK for you. However, a motor whose fuse has tripped will be more prone to tripping again because the fuse has a finite life.

For each motor that you intend to run beyond 9.15 Volts (the voltage of a set of fresh AA cells), do your research and find the industrial rating of the internal motor. If that says 12 volts then that particular motor type would be OK at 12 volts for a longer period. For most of the LEGO motors, provided the industrial rating is more than 9 Volts, I would recommend a maximum of 12 volts; I doubt very much whether the industrial rating is any higher than that for any LEGO motor type. You could achieve 12 volts by using 2x 1.5V cells and 4 dummy batteries in a second battery box. 4 cells and 2 dummies for rechargeable AAs whose full voltage is 1.2V.

At a higher voltage you will get more speed out of the motor because the speed is proportional to the voltage for a dc motor. If you have moderate duty cycle and make sure the motor does not get hot then you should be OK for a while.

For a dc motor with a commutator there are sparks generated as the contacts are made and broken. The higher the voltage, the stronger those sparks and the quicker the motor's life is used up.

The most efficient use of a dc motor is for it to run at half its no-load speed.

The IR Receivers contain motor drivers that are H-bridges with flywheel diodes. If you understand what's going on in the circuit as you use them then that's OK. You need to pass on the learning with the suggestion so that everyone understands what they are doing. Exceeding ratings without understanding just leads to product failure when you have invalidated the warranty.

TLG are good at replacing faulty parts but it's experiments like these that drive them to change the plug system. The backward compatibility of PF to 9V always left the system open to uses that TLG did not intend and could not possibly recommend for safety reasons. I still hope for some backward compatibility from the new plug system but it may be less likely because TLG need to meet the toy safety regulations and discourage connections outside their design intent.

I've done some electrical hacking myself and have burnt out a few motors in my time but these days I aim to maintain reliability with the results. When I use a bench power supply I tend to stick to 9.15 Volts as the maximum.

I have found the limit of PF train motors, which are currently the best source of power at high speed (except for obsolete 5292 motors). The experiment seeks to launch a Ninjago Airjitzu spinner from pure-LEGO electrical power. It could not quite launch with 2x PF M motors at 15:1 gearing up. 2x PF train motors and a freshly-charged LiPo battery did achieve a launch. A 5:1 gear-up ratio was good but a higher ratio than that did trip the motor fuses.

As someone who is prepared to experiment, you have potential as an engineer. LEGO and electronics kits are what guided me in that direction.

Despite the limitations on what a professional engineer can recommend, engineers know more and do get to over-rate things occasionally!

Mark

Wow Excellent post Mark, This is very good info. Thanks for posting it. When it come to the dual power supply I don't consider it a electrical hack, it just the nature of electricity at work that has been overlooked by settled science.

About connecting two battery boxes parallell: I´m building a vehicle with 5292 motor, and it stalls way to early. Been reading around whole day, but not sure anyway, so I ask for safety reasons... Is it possible and safe to connect two battery boxes in parallell to get more current? If so, can I power one receiver (V2) with those two boxes, or should I go for two separate "power units" each containing one box and one receiver (mating up at the motor)?

Connecting two battery boxes in parallel only increase the total amount of current available for the DC motor. The DC motor will still run as good as it if it had one battery box connect in theory. See the motor going to use as much current as the motor needs for the rotor armature Magnetic Field to be able to turn the shaft. Increasing the Current is like making the gas tank bigger for the car to drive with, increasing the voltage is like increasing the volatility of fuel to increase the fuel reaction in the combustion system. More volatile the fuel the faster the car can go if the engine can handle all the stresses with out it blowing up. The best way to increase Current is to use the Batteries with the most amount of current so you can have more current available in the space provided in one battery box.

[zux]

Sorry for my poor understanding in electronic part of this solution. Would this work with batteries that don't have much juice left? I mean, 12 batteries should have not less than 12 volts left.

[Boxerlego]

Sorry for my poor understanding in electronic part of this solution. Would this work with batteries that don't have much juice left? I mean, 12 batteries should have not less than 12 volts left.

This wouldn't work as well with a dead battery.

[Brickthus]

Sorry I've not been around for a while - been too busy building BB-8!

On 13/03/2016 at 5:11 PM, rocklego said:

Mark

How are you so sure that industrial voltage rating for LEGO motors is more than 9 V ?

Do you have any prove like datasheets for internal motors ?

I just want to make sure not shortening the life of motors if supplying more voltage than 9 V.

Some may be 9V and others may be 12V.  Research into data sheets will reveal the ratings of each one.

Philo tests LEGO motors at up to 12V.  He may know more.

9.15V is possible for any 9V motor (without research) because that is the voltage of a fresh set of batteries, which is the powering method recommended by TLG.

On 24/05/2016 at 1:55 PM, morson1 said:

About connecting two battery boxes parallell: I´m building a vehicle with 5292 motor, and it stalls way to early. Been reading around whole day, but not sure anyway, so I ask for safety reasons... Is it possible and safe to connect two battery boxes in parallell to get more current? If so, can I power one receiver (V2) with those two boxes, or should I go for two separate "power units" each containing one box and one receiver (mating up at the motor)?

If the motor is stalling then you will need an additional motor.

I would suggest either using two 5292 motors, or gearing down by 3:1.  If you use two motors, you might need a battery box and IR Receiver for each one.  This would effectively put two battery boxes in parallel but only once the electrical power has been converted into mechanical power.

I have done the same for my BB-8 Droid.  In the update I will post soon, I used 1 XL motor for each half of the spherical shell, driven from a single IR Receiver and a LiPo battery.  This allowed BB-8 to move a bit, up to 1 metre in each direction, but after a few tries a V1 Receiver stalled and a swapped-in V2 Receiver complained of overcurrent/overheating by making a squeak/whistle sound.  In reality I had tripped the LiPo battery's 800mA overcurrent trip.  I changed to using 2x XL motors each side, driving one from each of two IR Receivers set to the same channel and using the corresponding red/blue output of each receiver for each side, with a LiPo battery for each IR Receiver.  This has doubled the current capacity whilst the power from the two batteries comes together only as the motors are linked mechanically; there is no electrical connection between them.  BB-8 now moves with his head on and can drive, turn and spin without tripping any electrical limits - nearly time to make a video!  A similar system is used on trains, where two PF locomotives may be set to the same IR channel and the power only comes together at the rail.

You should not try to unify the driving components electrically but you should use a motor on each of two electric drive systems and unify the power mechanically.  Then make sure the two battery sources have similar age batteries to get the same state of charge and minimise one motor pushing the other.

Mark

[msdobrescu]

Hi, I have a 42069, which is heavy, so I have used 4L's and one battery box, that will trigger the overloading safety. Is it possible to power the 4L's with two parallel battery boxes and one IR receiver? Thanks.

Edited June 5, 2018 by msdobrescu

[Permo]

Yes you could with a V2 receiver, 2 L motors per channel.