Ride On Wiring Guide

Upgrading the wiring of a stock ride on kids toy is necessary once you go down the path of modifying motors and increasing the operating voltage. This article will cover basic functions of the most common ride on toys wiring and possible modifications to consider to ensure safe reliable operation for your kids.

Wiring Basics

Most two wheel drive ride on vehicles available today are wired per the wire diagram shown below. and follow the description provided. The ride on vehicles that do not follow this description are those with additional electronics that incorporate software starts like the Power Wheels Barbie Dream Camper.

Battery

There isn’t much to say regarding the battery, you are here so you know what a battery does.

Throttle Plunger

There is a plunger switch (Throttle pedal) that has two contacts (a normally open and a normally closed) when the throttle pedal is released the normally closed contact is in the closed position shorting the motors, shorted brushed motors puts the motors into a brake condition where a short is the hardest braking effort that can be physically applied with just the motors (note that this is not the same as regenerative braking like in an electric car). A common practice is to wire a resistor in series with the Normally Closed (NC) contact to decrease the braking effort to make a smoother transition from power to braking.

When the pedal is pressed, the Normally Open (NO) contact is closed and the NC contact is opened removing the short across the motors and connecting the battery to the motors.

Gear Selector (High / Low / Reverse)

The gear selector is made of two Double Pole Double Throw (DPDT) switches. The gear selectors physically do not allow for the motors to be wired in parallel and be in reverse at the same time.

Forward / Reverse Switch:

Forward and Reverse is selected using the first switch, this is accomplished by changing the polarity of the battery connection to the motors reversing the flow of current through the motors.

High / Low Switch:

Selecting high speed vs low speed changes the motors from being wired in series for low to parallel for high.

High vs. Low (Series vs. Parallel) Explanation

When in low, the motors are wired in series, this means that the entire battery voltage is applied to the first motor then the second motors, any voltage absorbed by the first motor is taken from the total battery voltage so the second motor has less voltage available.

For this example, lets assume a 12V battery is being used. If both motors are equal, this means each motor will only see 6V (12 divided by two motors). Total power is equal to voltage X current (P=VI) or voltage squared divided by resistance (P=V^2/R). We will assume each motor is 1 ohm, this means total power (watts) of both motors when in series will be (12 X 12) / 2 = 72 watts or 36 watts per motor (Please note that the actual power of these toys is significantly larger, even stock)

When the motors are put into high or parallel mode, the total power will be (12 X 12) / 1 = 144 watt per motor or 288 watts total. When you complete the mathematical equations to calculate how much power is required to double your speed, you will get the answer of approximately four times the amount of power is required to double your speed. This equation explains why high is double the speed as low but requires four times the power.

Stock kids ride on toy wiring diagram

Actual Power Values

I have taken the following measurements from my kids toys, note that these values will change dramatically based on many different variables (Voltage, Motors, Battery type, rider and vehicle weights)

This section will only provide details for high mode as low is always going to be lower and not a concern. Also, if you are here I am guessing you are interested improving the speed.

Stock Motors at 12V (Actual voltage ~14V)

Stock motors carrying two young kids (60 pounds total) on level ground in average cars draws about 10A continuously and will surge to 20A when going up an hill or just starting. This is means the stock vehicles are designed to handle about 20A of continuous current and the typical wire gauge (Diameter of the stock wires) and contacts used agree with these measurements.

Aftermarket 550 Motors at 12V (Actual voltage ~14V)

Once upgrading to higher speed 550 motors like the Traxxas Titan 21T motors, the current about doubles with the same 60 pound kids, about 20A on level ground and 40A going up hills and starting. If you remember our calculation from earlier, it takes 4 times the power to double the speed, well, to increase speed by 50% takes about double the power and upgrading to Traxxas 550 Titan 21T motors increases speed from about 5MPH to 8MPH.

This extra current increases heat within the contacts and wires within the vehicle, every car I have upgraded the motors in, shortly had failed plunger switches and the gear selectors began to melt from the excess power the car just wasn’t designed to handle.

Aftermarket 550 Motors at 18V (Actual voltage ~ 20V)

Increasing the voltage from 12V to 18V provides another 50% increase in power, however, since the motors are spinning faster, their impedance is larger so the current stays roughly the same, with the same 60 pounds of child, the current stays at about 20A on flat ground and 40A when going up inclines and starting. Going up to 18V with aftermarket 550 motors, the expected speeds are about 10MPH which requires 4 times the power as a stock vehicle.

Aftermarket 775 Motors at 18V (Actual voltage ~ 20V)

Upgrading to larger motors (like the Traxxas Titan 775 10-Turn motors don’t impact the speed but they offer significant improvements in torque. The average power draw with the same kids is roughly the same as the vehicle is traveling at about 8MPH, however, these motors can draw a lot more power once going up steeper hills and adding more weight to the car. These motors draw about the same 40A that the 550’s did at 18V.

Aftermarket 775 Motors at 24V (Actual voltage ~ 27V)

Once operating 775 motors at 24V, the car will have the same top speed around 10MPH (it will depend on the exact motor but I find most are in that range + / - a couple MPH) as 550’s at 18V, but they will have a lot more torque available

Power Draw Overview

Here are the approximate peak power draws from the batteries based on 60 pound rider weight in a light normal two seater ride on toy. These will increase with rider weight.

Stock motors at 12V = ~280 Watts @20A (140W per motor)

Stock Motors at 18V = ~400 Watts @20A (200W per motor)

Aftermarket 550 motors at 12V = ~560 Watts @ 40A (280W per motor)

Aftermarket 550 motors at 18V = ~800 Watts @40A (400W per motor)

Aftermarket 775 motors at 18V = ~800 Watts @40A (400W per motor)

Aftermarket 775 motors at 24V = ~1080 Watts @40A (540W per motor)

The continuous power and current values when traveling on flat ground tend to be about half of these values.

Recommended Wiring Upgrades

Once you make the decision to upgrade the motors to higher powered ones, you will need to come up with a wiring solution. You will need to install an alternate method of changing direction and going forward, the best solution (other than an H-Bridge speed controller like the DRV230BD) is to use automotive relays, these are typically rated for 30A, the coils will work with 12 - 24V and they are cheap. You can have the normal position (NC contacts) provide power to the wheels in the forward direction and the NO contacts provide power to the wheels for reverse. The gear selector can control the relay coils for forward and reverse. I have done this and just never wired anything for low, the kids don’t use it.

For the throttle plunger, you can have another relay that enables / disables power to the direction relay. You can also create a braking circuit that shorts the motors and disconnects power from the motors when the throttle relay is de-energized. You should get a lot of hours of use before any relay contacts fail, I only used this setup briefly before I began designing my own H-Bridge solution to eliminate any high powered mechanical parts (except the motors) that wear out and decrease reliability.

When installing the relays ensure the wiring from the battery(s) is changed to 10AWG, 12AWG will be fine but if you are going through the effort, put in 10AWG. The stock wiring will drive the relay coils from the gear selector and throttle plunger.

Below is an image of a melted connector to the gear selector of my sons KidsTraxx police car, this car was running on 12V with Traxxas 550 21 Turn motors and no other modifications. Once you start to pull more power you need to upgrade the electronics on these toys.

Melted connector from KidTraxx police car gear selector from running aftermarket Traxxas 550 21 turn motors at 12V.