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How do I reduce the speed of a 12v childrens car

kellys_eye

Jun 25, 2010
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If the accelerator pedal is operated by a pivoting lever action you can move the pivot point to limit travel - means drilling a new hole in the lever arm.

Nice car though. Lucky kid!

Redneck solution would be to fix a block of wood behind the accelerator pedal.....
 

73's de Edd

Aug 21, 2015
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Sir surreyman . . . . .

BOY ! . . . . . .that little thing is as neat as they come.

If I am guessing correctly on some of the the partially hidden wiring runs.

If you tried one less cell out of circuit . . . likely it is as the illustration below now shows.
With you pulling the connection at C and pulling it back to E area and then disconnecting the connection currently at E and place on the former C connector . . . as the bottom illustration shows.

PLUS . . .my . . . . interconnect wiring links was positively confirmed with your last new photo.

As far as torque, and the wire gauge seen being used , this thing must really be geared down from drive motor to wheel drive.
My recommendation agrees with another's, 1000%, and that would be the mechanical implementation of the physical limitation of the downward travel limit of the accelerator pedal.




PHOTO MARK-UP . . . . .

v17CMJC.jpg


73's de Edd
.....
 
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Bluejets

Oct 5, 2014
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I think he removed link B-C and refitted cable A to C which would be correct.

Perhaps the controller just does not like low voltage.

Wondering what is the extra cable from terminal "F"...??

Hidden wiring does not help.
 

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surreyman

Sep 18, 2018
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I think he removed link B-C and refitted cable A to C which would be correct.

Perhaps the controller just does not like low voltage.

Wondering what is the extra cable from terminal "F"...??

Hidden wiring does not help.
B currently joins with C so i disconnected both ends. I then moved A to C - My logic was i had removed cell 1 from the chain. The jeep did not work- there are actually 4 cells as the final one is located in the rear. i have been told that i can put another varable resistor after the current one thats on the end of the throttle pedal (its a black plastic thing where the two halfs slide in and out of each other when the pedal is pressed)
 

Bluejets

Oct 5, 2014
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I think it's about time you supplied a bit of a sketch of the layout and what is wired to what and how.
 

73's de Edd

Aug 21, 2015
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Wondering what is the extra cable from terminal "F"...??
Front headlights + other lights . . and possibly it has a horn.
 

dave9

Mar 5, 2017
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Won't the throttle be going to a potentiometer or some other variant of a variable resistor? If so I would measure its resistance at the various pedal positions and use a switch to switch an added resistor in and out of the circuit to limit the sensed throttle position.

You hide the switch so the kids don't know about it, then just flip it back when someone else is driving.
 

Alec_t

Jul 7, 2015
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i can put another varable resistor after the current one thats on the end of the throttle pedal (its a black plastic thing where the two halfs slide in and out of each other when the pedal is pressed)
Can you provide a clear picture of this variable resistor thing with the 'two halfs', and its connections?
 

surreyman

Sep 18, 2018
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the above pic is the variable resistor. one end is connected to the end of the throttle and the other to the chassis . the two halfs slide in and out of each other. The manufacturers of the car in vietnam dont know much about the electrics. they just buy a package from a company called www.cq-motor.com . they arent interested in talking as they produce high volumes for electric town cars.
 

Minder

Apr 24, 2015
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So is there any way you can mechanically restrict the stroke of the control actuator/accelerator rod?
M.
 

Alec_t

Jul 7, 2015
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Hard to imagine that being a variable resistor, yet alone one able to handle 30A or more. What are its dimensions (roughly)? How far does it slide?
It doesn't seem to have any way of connecting to that 3-way plug/socket alongside.
 

Tha fios agaibh

Aug 11, 2014
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Hard to imagine that being a variable resistor, yet alone one able to handle 30A or more.
I agree. Like I said the hotweels type cars dont have a variable resistor, just switches.

I suspect it may be two stage (slow/fast) switch that drives a high current relay.
 

kellys_eye

Jun 25, 2010
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Assuming the sliding bits are actually a potentiometer (and the three wires/plug seem to go to prove this) then all you need do is break one of the coloured wires and add an extra resistor.

But WHICH wire to cut? The three wires will connect to the 'top', 'bottom' and 'wiper' of the potentiometer - this can be determined using a test meter (set to resistance) to discover bothe the FULL value of the potentiometer AND prove which is the 'wiper' connection.

If we assume that the GREEN wire (middle) represents the wiper connection then we need to cut either the red or yellow and add an additional resistance that is (say) 50% of the total value of the potentiometer as-a-whole. This will move the throttle position closer towards either the top speed OR the lower speed end of the range depending on which end of the potentiometer (i.e. which wire we cut) is used.

You could do this by experimentation - buy a selection of resistors, say 10k, 47k, 100k, 220k - and try them until you find one that gives the right range or (potentially) purchase another 220k potentiometer and put this in place instead. This will allow you to 'dial' the speed range (maximum) that you want (assuming the 220k value is in the ballpark range required).

There's nothing for it but for you to get a test meter and measure the potentiometer value both to find out the parts you need and find the right wire we need to cut.....

Over to you!
 

surreyman

Sep 18, 2018
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Assuming the sliding bits are actually a potentiometer (and the three wires/plug seem to go to prove this) then all you need do is break one of the coloured wires and add an extra resistor.

But WHICH wire to cut? The three wires will connect to the 'top', 'bottom' and 'wiper' of the potentiometer - this can be determined using a test meter (set to resistance) to discover bothe the FULL value of the potentiometer AND prove which is the 'wiper' connection.

If we assume that the GREEN wire (middle) represents the wiper connection then we need to cut either the red or yellow and add an additional resistance that is (say) 50% of the total value of the potentiometer as-a-whole. This will move the throttle position closer towards either the top speed OR the lower speed end of the range depending on which end of the potentiometer (i.e. which wire we cut) is used.

You could do this by experimentation - buy a selection of resistors, say 10k, 47k, 100k, 220k - and try them until you find one that gives the right range or (potentially) purchase another 220k potentiometer and put this in place instead. This will allow you to 'dial' the speed range (maximum) that you want (assuming the 220k value is in the ballpark range required).

There's nothing for it but for you to get a test meter and measure the potentiometer value both to find out the parts you need and find the right wire we need to cut.....

Over to you!
 

Ylli

Jun 19, 2018
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Do you have an ohmmeter? Connect one lead to one of the wires, and the other lead to a second wire. Record the resistance with the 'accelerator' in both ends of it's extremes. Now do the same with a second pair of leads. And with the third pair. Also note the trend as you move the 'accelerator'.

i.e. pairs
A to B
A to C
B to C
 

surreyman

Sep 18, 2018
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thanks for that - i had much the same answer from another guy but he said go and test all three wires for voltage- he said one should be 5v , one zero and the other would change dependant on how far you pressed the accelerator. i tried with my voltmeter and seemed to get zero readings on all although i am foxes as where to put the earth of the tester as the car isnt earthed through its chassis
 

surreyman

Sep 18, 2018
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thanks for that - i had much the same answer from another guy but he said go and test all three wires for voltage- he said one should be 5v , one zero and the other would change dependant on how far you pressed the accelerator. i tried with my voltmeter and seemed to get zero readings on all although i am foxes as where to put the earth of the tester as the car isnt earthed through its chassis

the pic i have just uploaded is of the control unit for the car
 

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Minder

Apr 24, 2015
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I am guessing it could be a BJT driver with PWM control via a input pot, adding a resister may not do anything but make the degree of acceleration different.
What is the answer on correction to the stroke of the actuator?
M..
 

Ylli

Jun 19, 2018
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thanks for that - i had much the same answer from another guy but he said go and test all three wires for voltage
Do the resistance measurements with the unit unplugged - just like it is shown in your picture.
 
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