Introduction: Power Wheels Mods - Master Kill Switch and Charging

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The Problem:

Santa brought a Power Wheels Jeep to my kids this Christmas. I was quite surprised that there was NOT a master ON/OFF switch on the thing. And of course, Christmas morning, the first thing my daughter did was hop in and try to run of her brother.

To charge the car, the manufacturer also wants you to unscrew 2 screws on the hood, unhook the battery from the motors, hookup the charger, leave it charging for 18+ hours, and reverse the process to put it all back together. This proves to be a giant pain.

The Solution:

Add a Master Kill Switch.

Improve the charging process.

Luckily, the factory connectors are just 4-pin trailer connectors (aka 4-wire trailer connector). So these mods can be added in without cutting or modifying any of the existing wires. The only non-reversible modifications are the 2 holes that need to be drilled.

Parts:

Tools:

  • Screwdriver - Phillips (to open the hood)
  • Wire cutters
  • Wire strippers (these are optional, cutters can be carefully used, or a good pocket knife)
  • Crimper/Pliers
  • Multimeter
  • Trickle Charger (I have a Schumacher Battery Companion similar to this LINK)

Step 1: Master Kill Switch

This is needed for a couple of reasons. It allows you to easily disconnect the battery from the motor. This is a great safety feature, especially for motorized toys and children. This also prevents the motors from being run while the charger is on.

Process:

You will only be using two wires of the 4-wire trailer plug. On my car, the RED/+ of the battery matched the bottom GREEN wire and the BLACK/- matched the WHITE wire of the trailer extension harness. The middle wires (BROWN and YELLOW) are not used and can be cut out.

I am using a rocker switch with an LED. The switch has 3 inputs in the back for EARTH, LOAD, & SUPPLY. If you are just using a basic rocker switch, you may only have 2 inputs for LOAD & SUPPLY. I am switching the POSITIVE side GREEN wire.

Step i:

  • Make 3 pigtails for the switch. I made each of them ~18" so that the hood could be opened and closed without a problem.
  • Cut 2 sections of RED wire and 1 section of BLACK wire.
  • Strip the ends
  • Crimp a FEMALE BLADE CONNECTOR to one end of each wire. (leave the other end bare because it will be wire nutted end).

Step ii:

  • Cut the GREEN and WHITE wires, of the trailer extension, in the middle
  • Strip all the ends.

Step iii(alternate):

(SKIP TO THE NEXT STEP IF ADDING THE TRICKLE CHARGER)

  • Combine the 2 WHITE wires and 1 BLACK wire and wire nut them together.
  • Combine 1 RED wire and 1 GREEN wire and wire nut them together
  • Combine the last RED and GREEN wires and wire nut them together.
  • Wire the switch
    • BLACK wire to Earth
    • RED wire from BATTERY to Supply
    • RED wire from MOTOR to Load

Step 2: Trickle Charger Pigtail

This is a nice feature/upgrade. In the stock configuration, you have to unscrew two screws and disconnect the battery to charge it. With a pigtail added, you can plug in a trickle charger without needing to go through that process. Also, a trickle charger is HIGHLY recommended over the use of the stock charger. If left on too long, the stock charger will burn up your battery. A trickle charger will completely charge the battery and automatically decrease to a low power charger to maintain the battery's full charge without overcharging it.

If you are buying a new trickle charger, it should come with a pigtail.

If you are using the extension mentioned in the parts list, you will need to double check which end to cut off. I used my multimeter to determine which pole of trickle charger was 12V+ and Ground-.

Step iii:

  • Cut and strip the ends of the 2-pin plug (trickle charger plug)
  • Combine the 2 WHITE wires from the trailer plug, the 1 WHITE wire from the 2-pin plug, and the 1 BLACK wire from the LED SWITCH and wire nut them together.
    • Run the BLACK pigtail to the EARTH of the SWITCH
  • On the BATTERY SIDE
    • Combine 1 of the RED wires to the switch, the RED wire from the 2-pin and the GREEN wire from the BATTERY side of the trailer plug and wire nut them together
    • Run this RED pigtail to the SUPPLY of the SWITCH
  • On the MOTOR SIDE
    • Combine the last RED wire and the GREEN wire from the MOTOR side of the trailer plug and wire nut them together.
    • Run this RED pigtail to the LOAD of the SWITCH

Step 3: Test, Drill, Mount....Profit

Test:

You should have all of the wiring finished. You have essentially made a wiring harness. Plug your new harness into the car and test that everything functions.

  • Start with the switch OFF and test for the correct polarity on the trickle charger plug. The RED should by 12V+ and the WHITE should be ground. (If it's backwards, your multimeter will probably read -12V)
    • If you get no voltage, you have the trickle charger running through the switch. you need to move the RED wire of the trickle charger to the other GREEN wire.
  • Turn the switch ON. The LED should light up.
  • Try pushing the throttle pedal with the switch ON and OFF. The wheels should turn or not turn appropriately


Drill:

  • Drill a hole for the SWITCH.
    • **BE CAREFUL OF THE INSTRUCTIONS ON THE PACKAGE**
    • My package said to drill a 1" hole. That would be entirely too big.
    • I used a 7/16" drill bit and had to just slightly enlarge the hole for the switch. (1/2" would work, but would be a little loose)
    • I put the switch on the middle of the hood, to look like a hood latch/emblem. I also considered running it to the dash, or even the back of the car.
  • Drill a hole for the Trickle Charger
    • I think I used a 3/4" or 1" paddle bit. The whole size is not as big of a concern for this, it just needs to be big enough for the plug to fit through.

Mount:

  • Unhook the wires from the SWITCH
  • Mount the SWITCH in the new hole
  • Hook the wires back to the SWITCH
    • RETEST the switch
  • Drop the trickle charger plug through the hole, so that it can be accessed from outside the car.

Finish:

You should be done. Use some zip ties or tape to clean up the wiring and close the hood.

Crack open a cold one and admire your work.

Remember to leave the SWITCH in the OFF position when you have the trickle charger plugged in.