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4,4kW 24V electric go-kart for kids.

wekar 22860 29
This content has been translated » The original version can be found here
  • The idea came from the fact that the 5-year-old daughter is willing to drive all kinds of vehicles. He packs on a motorcycle, he wants to drive the car, he stays in the tractor with his grandparents, etc.
    So I decided to build something for her that would allow to develop certain habits of the driver and provide a dose of adrenaline and child's fun. The idea fell on a go-kart. However, the noise or the risk of being scalded by an internal combustion engine, the lack of my control over the stopping of such a vehicle in an emergency, prompted me to switch to an electric drive. Remote (radio) disconnection of such a drive seems to be easier. It is also possible to regulate the speed or acceleration.
    There are no special assumptions about power or speed.
    While searching OLX, I found a go-kart close to my place of residence. Unfortunately, it turned out that it was in parts and the fact that I bought it was the biggest mistake during the whole construction. Few things fit, I got a pile of parts from the seller, probably of various designs, heavily damaged and often thrown away.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    The frame was already powder coated black, which was not quite ok. I had a lot of welding modifications to do, so I will have to re-paint it anyway.
    The first move was the cutting of the internal combustion engine, seat and steering wheel supports. I wanted the seat and the steering wheel to be centrally located in relation to the frame, and not, as in the exhaust fumes - moved away from the vehicle axis. The drive was to be installed centrally behind the driver's seat.
    Also trivial things like painstaking cleaning of elements, then painting them orange, because that's what my daughter chose :-) or printing some of the items took a long time.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    I will use two 2.2kW series-shunt motors for the drive. They have one huge drawback, their S2 performance characteristics are 1.2Min at S3 = 4%. Previously, they worked in battery-powered palletizing trucks, driving hydraulic lifting pumps.
    So it will be necessary to add forced cooling. During the tests, it turned out that the motors heat up the most around the commutator. So that's what I'm going to focus on and cut openings in the cover, additionally forcing the airflow with the fan.

    4,4kW 24V electric go-kart for kids.

    I placed the motors opposite to each other, which involved a slight modification of one of them so that it rotated in the opposite direction. Both, being identical, have CW speed ex works. In my case, the change was to change the polarity of the stator windings.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    After a surprise modification, it turned out that the engine consumes twice the current at idle speed compared to the second engine. Suspicion fell on the brushes that were not torn in this direction. And probably in fact, this was the reason, because after treating the brushes with sandpaper wound on the commutator and then several minutes of work at idle speed, the current decreased significantly, but it is still greater than its twin brother. At maximum speed, the engine without modifications consumes about 16A. Engine after modifications about 22A. Perhaps still a cracked housing, and at the same time the bearing housing is affected. It is already welded, but the tests are not done today.

    4,4kW 24V electric go-kart for kids.

    The motors will be mechanically coupled to each other. A gear rack will be installed on the clutch.
    The engine mounting block made as a monolith. In addition, a great place to screw the PWM controller housing. The engine block will be bolted to the rails of angles with the possibility of sliding for tensioning the chain.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    Driver only purchased on e-bay. According to the manufacturer 200A, we'll see.
    The aluminum housing is also to serve as a heat sink. Unfortunately, the controller's adjustment potentiometers are located on the same side as the originally installed piece of aluminum, the heat sink. It would be much better to screw the driver to the housing with a heat sink, but well. I am going to choose an aluminum beam in such a size that after screwing the cover it can still be screwed to the heat sink. Trouble opening, but a compromise must be found.
    The above-mentioned potentiometers can be used to set the maximum current, the battery charging current in the case of regeneration mode and the acceleration ramp.
    The controller can work in regeneration mode. I don't know what it will look like while driving, if the motors will be a "good" brake and some of this energy can be returned to the battery, but I intend to use this function.

    A very provisional test of the driver on one engine.


    Link


    Batteries. Many similar DIY designs I have seen have cells in use, e.g. lithium-ion.
    For me, these will be ordinary, heavy, two 12V 50Ah gel traction batteries. One weighs 20 kg according to the manufacturer, a massacre. I hope, however, that it is enough to have fun and you can "go crazy" these several dozen minutes to an hour.

    4,4kW 24V electric go-kart for kids.

    Successful try-on of the power unit.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    A floor made of waterproof plywood must suffice for now. Its edge in the photos is exposed after cutting, but when the go-kart is disassembled for painting, the plywood will be painted as well. There will be batteries on the shelves on the sides of the go-kart.
    Accelerator pedal mounted on a printed bracket, of course the right color.
    As I am writing this, the brake pedal and its mounting are also printed.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    The vehicle is at the stage as shown in the photos. Roughly quite a lot to complete.
    Electrical system, brake, engine clutch, engine cooling, maybe lighting. To weld in the roll bar behind the driver, in the case of a flip. Most likely something ala seat belts too. Of course, remote radio shutdown of the drive. From time to time, I am going to post photos of the progress of work, as long as I have to finish it.

    2018-04-11

    After a long break, it's time for a few words what you managed to do.
    Following the advice of Euzebiusz23091998, I made a steel brake. So far, it is only a cable with a pump attached, waiting for the clamp, and a limit switch to disconnect the contactor during braking and in the future, to turn on the regeneration and maybe the STOP light.

    4,4kW 24V electric go-kart for kids.

    In the meantime, engine cooling was added. I attached a 24V fan, which is doing quite well through a few holes in the cover. During the tests, driving around 15 minutes, the engines were only warm.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    We also managed to install the electrical installation and make a switch panel for the driver.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    I also installed a remote control module. The main contactor can now be switched off with the remote control in the event of "w".

    PROBLEMS!
    During the tests, it turns out that there is a lot of room for improvement.
    The kart does not "pull" as I would expect. I'm disappointed.
    The controller becomes very hot. The resistance to turning, resulting from the lack of a differential and a lot of weight on the rear axle, means that this stroller is barely pushed when the front wheels are turned. Thus, the controller and the motors have something to do. When driving slowly, this negative effect only gets worse. When driving straight ahead, the go-kart runs very lightly.
    After consulting the forum on electric cars, I'm going to convert the drive. The axle will be cut in half, the motors will be decoupled and each motor will be individually
    drive one rear wheel of the go-kart. This is to give the effect of a limited slip differential.
    A large heat sink will also be installed for the driver. Even though the manufacturer says 200A for his work, I am beginning to have some doubts.
    Additionally, a seat to lift, at least 20mm. Now, on unevenness, often the "chair" strokes the street.
    Accelerator pedal. As I purchased a hall effect pedal, another problem arose. On an ordinary potentiometer, during tests, the controller stopped the engine at the extreme position of the resistor. The motor current was dropping to zero. Unfortunately, this is not the case with Hall. Despite the extreme position, the controller supplies voltage to the motors and they start spinning. It turns out that the hall gives some voltage in its minimum position, so the controller reacts to it. Unfortunately, the controller itself does not have any regulation for this parameter. I don't know what to do, whether to add a switch that detects the beginning of the pedal's movements and only then gives the control voltage, or to buy a potentiometer pedal. For now, the brake pedal disconnects the main contactor, so you can stop the go-kart, but just release it for the wheelchair to slowly roll.

    Despite the fact that it is not perfect, the young one likes it.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids.

    Cool! Ranking DIY
    Can you write similar article? Send message to me and you will get SD card 64GB.
    About Author
    wekar
    Level 14  
    Offline 
    wekar wrote 152 posts with rating 37, helped 2 times. Been with us since 2004 year.
  • #2
    bubu1769
    Level 40  
    4.4 kW for a child, nice :D
    The project is very interesting, I am curious how it looked ready. As for the batteries, I think that at the very beginning to learn how to use the vehicle, their weight and not too large capacity will be an advantage.
  • #3
    Euzebiusz23091998
    Level 15  
    I have doubts about the printed parts of the brake. I would not dare to ride something like that, let alone give it to a child. The brake, however, is quite an important element of such a go-kart, if the gas comes off, at most it will not move, and the brake? Headband + belts is also a bit of a difficult topic. If a child is strapped in straps and overturns the kart by some miracle (low mass point + relatively wide track), what about his hands? How will they get underneath somewhere? In professional toys of this type, but with larger dimensions and power (where such arches and straps are), the driver has his hands tied on special cables to the steering wheel, which in the case of W do not block the possibility of twisting the hands, but this is a bit offtop on this topic. Are these green and orange discs on the axis also printed? Will it withstand eternal vibrations or will it lose its axis in a moment? 4.4kW for a five-year-old is, in my opinion, much too much. I hope you limit this power reliably. I used to ride mopeds with similar power (weight probably also) and 70 km / h was not a feat, I cannot imagine a child driving at such speed.

    But overall the design has a very nice potential, haven't you thought about BLDC motors instead of yours? They are quite easy to buy in a variety of sizes and prices. I would like to tour something like that myself :D
  • #4
    E8600
    Level 39  
    Such high-torque power of electric motors is, in my opinion, less safe than an internal combustion engine.

    As for the age of the child, in countries where motocross is popular, much younger children ride with their parents.

    Link


    An interesting project, but here I see a toy for my dad rather than my daughter. :)
  • #5
    Andrzej42
    Level 27  
    I gave myself a Chinese 1kw dc engine for the quad bike - and I see that it may be too big. For a child, I would give one with 250 W at the beginning.
  • #6
    wekar
    Level 14  
    Yesterday we did a little driving around the cart. The son was doing fine. My father got in and hit a tree :-)
    I pumped the air to 4bar. The tires are nicely bulged and the resistance of the stiff rear axle is slightly smaller. The go-kart speeds up quite slowly, but when it does ... I get 50 km / h from Calculations. It's too fast for kids, so I'm thinking of some 1: 2 intermediate gear. Acceleration will increase, speed will decrease.

    The first photo shows a remote control for disconnecting the main contactor.

    4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids. 4,4kW 24V electric go-kart for kids. [/ img]

    The added heat sink probably fulfills its function. Seat raised some 25mm.
    cdn.
  • #7
    ^ToM^
    Level 39  
    First of all, as you have noticed yourself, these motors are not a good choice.
    Moreover, for a child, 4 kW is too much power, many times. For such a child the engine power of 200-300 W. I would not entrust a few years old child with a device with a power of several kW to play, even under my supervision.
    For a child, the vehicle must reach several km / h, so that I can react and run if something unpredictable happens. This speed limits the power to just 300 W. Well, unless you intend to install a speed limiter there. But then why push such powerful engines to it? Even if you were to exaggerate, 1000 W would be enough.
    View on power steering motor from passenger cars. It can be, for example, the one I wrote about in the post:
    Link
    It can also be from another 12 V car. They have several hundred W and are adapted to continuous operation and are built solidly, have multiple brushes. Well, a really solid and durable construction, perfect for such an application. You will find similar on the Allegro from several dozen zlotys per piece.
    View on factory adult bikes. Their engines have 200-300 W, the bike can even reach 25 km / h (moreover, it cannot remain a bicycle in the sense of the provisions of the Road Traffic Act).
    The device is nicely solved, but still think about this power or an effective speed limiter, if it is really for a small child.

    Greetings!
  • #8
    tos18
    Level 39  
    What is the gear ratio between the motors and the axle?
    What is the diameter of the wheel (tire)?
  • #9
    wekar
    Level 14  
    I agree with my colleague ToM. The power is high, but I suspect 300W, it would not move this stroller in a turn. The rear axle is too heavy and the resistance is very high. Besides, the sheer weight of the whole thing. I bet it is about 70 kg. For this driver, ... 300W is definitely not enough.
    "Mighty" engines give you acceleration, and that is the greatest fun, acceleration.
    I will add that I build what I have, not what I would like to do.

    To a friend tos18. The gear ratio is 13:32. Wheels 10 ". I understand that there will be confirmation of the theoretical speed of the cart :-)
  • #10
    tos18
    Level 39  
    No - I was just wondering where the enormous power of the engines is since the vehicle is muddy and I was also thinking about changing the gear ratio. I also saw an interestingly solved electric differential. A trivial idea, two motors driving the axle halves were connected in series.

    Have you solved the speed controller problem?
    Two ideas come to mind. The first one is a pedal microswitch that connects the setter output to the controller input, and the second is a resistive voltage divider or a diode connected between the setter output and the controller. The choice depends on how high is the zero voltage (at rest) coming from the set-up device.

    Is this your regulator?
  • #11
    wekar
    Level 14  
    I think so too. You have to definitely change the gear ratio. On the test tours, when the engines had already turned to higher revolutions, the truck was more dynamic.
    I did not worry about the setpoint. A micro switch will probably be the best solution. According to the supplier, the voltage is from 0.8V to 4.2V.
    Yes, I have this regulator, but probably not in the BETA version.
  • #12
    BANANvanDYK
    Level 39  
    Do not write that at this age it is too strong or too dangerous. Karting is a sport for young children. At 4, it starts (on a Chinese lawn mower, admittedly). However, such a toy can only be driven on go-kart tracks, not on sidewalks, parking lots, or wherever there is an opportunity. Unfortunately, sports for the parent with money, because the use of the card, trips to the track and its rental for training generate significant costs. Therefore, a question to the author of the topic. Have you been in contact with the people involved in the topic in your region? Because in my opinion, removing the stiff axle at the rear could be a bad move for this vehicle category. You only have a brake on the rear axle.
  • #13
    tos18
    Level 39  
    wekar wrote:
    Yes, I have this regulator, but probably not in the BETA version.

    If you have documentation, please share.
    Perhaps the muddy texture is due to the ramps in the regulator.
    The range of input voltages is also adjustable, as you can see.
    Perhaps it is just a matter of regulating the regulator (however it sounds).

    I have seen versions of this regulator with RS232 and programming options.
  • #14
    wekar
    Level 14  
    BanaVanDyk.
    No, I have not contacted anyone, because this is not the idea with this stroller. I just want to have fun with the construction, and the kids with the ride. Therefore, this axis will rather be divided, because it will allow less energy consumption, which will translate into play time.
    The brakes will of course have to be redone (they are still not there). Either a second axle for the rear axle or something for the front wheels, we'll see.

    tos18
    The documentation is identical to the one you attached (i.e. I have a beta version though). The controller has an adjustable maximum current and time for the acceleration ramp. Unfortunately, the ramp regulation does not help to improve the dynamics, it continues to muddy. There is also a third potentiometer for setting the battery charging current if you want to use energy while braking.
  • #15
    tos18
    Level 39  
    And current limitation regulation?
    In fact, the advantage of electric motors over internal combustion engines is the possibility of short-term overloading.
    Also pay attention to dipswitch 2 - maybe it will solve your problem with the speed controller.

    I would also put an additional T-shirt or a ring on the black wire between the terminal and the fuse. Wiping the insulation in this section can be very unpleasant.
  • #16
    Strumien swiadomosci swia
    Level 43  
    wekar wrote:
    I placed the motors opposite to each other, which involved a slight modification of one of them so that it rotated in the opposite direction.


    You cannot change the spin direction by yourself, you also have to change the position of the brushes in relation to the stand.

    Are these shunt motors?
  • #17
    tos18
    Level 39  
    I wonder how it would run on one - this unmodified engine?
  • #18
    Strumien swiadomosci swia
    Level 43  
    You know how I would use 2 alternators in 2 3-phase 120A drivers from alliexpress.

    They are definitely much more nimble.
  • #19
    tos18
    Level 39  
    How would you power the rotor (magnetizing winding)?
  • #20
    wekar
    Level 14  
    Yes it has a current limit, I called it maximum in the previous post.

    Series-shunt motors. I did not set the brushes, somewhere before someone advised me to check it, even by hearing. I intend to check it at the next disassembly of the drive.

    It doesn't get any better on one unmodified engine, but it certainly doesn't get 50% worse either. I think so.
  • #21
    E8600
    Level 39  
    In such devices, the driver is the workhorse, which is able to extract more than the rated values of the engine from the engine in a certain part of revolutions.
    For such applications, the best are high-speed brushless motors with a large diameter = high torque.

    I am also not satisfied with this combination of engines. They will not inhibit each other in a certain range of revolutions (I am not sure, let someone competent say that).
  • #22
    BANANvanDYK
    Level 39  
    And you're surprised that sitting too low. The cards have a chassis at a height of several millimeters from the asphalt. You had to use the pedal toy as a base for the modification, they are a bit taller. Once, I was at a friend's place and he was showing me his car. A 24V motor, probably from a scooter, driving one wheel. Two 12V batteries. The engine was powered by contactors, two "gears" + electrodynamic brake. Slow speed, but the kids have fun. You can drive it on the ground. I don't remember, but the conversion didn't cost more than PLN 500.
  • #23
    Strumien swiadomosci swia
    Level 43  
    E8600 wrote:
    They will not inhibit each other within a certain RPM range

    You have to measure the current of each individual.
  • #24
    wekar
    Level 14  
    Motors on the only controller should not "brake". Colleagues from the forum for electric cars give examples of such solutions, for example in transport carts. One controller, two motors driving each "their" wheel.
    We can leave the question of choosing a chassis for conversion. It is a subjective matter. Ah, I'm not going to change the color either :-)
  • #25
    Strumien swiadomosci swia
    Level 43  
    But now you have 2 different engines.
  • #26
    kortyleski
    Level 42  
    Two engines with completely different characteristics, rigidly connected with axles and powered in parallel is the basic error. Here, some of the power goes only to heat. In turn, when you disconnect them, it may turn out that the vehicle turns itself. Return to the original so that they both turn in the right direction.
  • #27
    jalop
    Level 24  
    kortyleski wrote:
    Two engines with completely different characteristics, rigidly connected with axles and powered in parallel is the basic error. Here, some of the power goes only to heat. In turn, when you disconnect them, it may turn out that the vehicle turns itself. Return to the original so that they both turn in the right direction.


    A colleague has already considered this error (:
  • #29
    bubu1769
    Level 40  
    Tricycles are quite unstable in turns, although it is also a matter of whether one wheel is in front or behind.
  • #30
    H3nry
    Level 32  
    Euzebiusz23091998 wrote:
    I have doubts about the printed parts of the brake. I would not dare to ride something like that, let alone give it to a child. The brake, however, is quite an important element of such a go-kart, if the gas comes off, at most it will not move, and the brake?

    I have no doubts after looking at the printed parts - you can see that my colleague has an idea about design. Probably the construction is still developing and I would love to read about the progress ... good luck.