How to Modify & Upgrade a Power Wheels Battery?

There are three main reasons why you might be looking to upgrade your Power Wheels battery:

  • The stock brand batteries are dead and upgrading the voltage is the better option.
  • Both you and your child are tired of the long charging times.
  • Your kid wants the ride to have a bit more speed.

You might be facing all these situations, and if so, we’re going to kill two birds with one stone by leveling up the standard Power Wheels battery. Just be aware that your warranty will be void the minute you cut off the battery connector—but it’s a risk worth taking.


Types of Batteries

There are two types of batteries you can use to upgrade the original Power Wheels battery. One is a sealed lead-acid battery and the other is a lithium battery.

Both have distinct features you should be familiar with.

Sealed Lead-Acid Batteries

The Sealed Lead Acid (SLA) batteries have a high discharge rate, but not as much as the lithium-ion battery. In some situations, this can be a disadvantage, but in this case, it’s advantageous as it means the battery won’t deliver excess power.

It’ll also take a lot more time to fully charge when plugged into the charger. It’s about 50% heavier than lithium so you’ll have to deal with the bulkiness.

Lithium-ion Batteries

Although these batteries have way more power than the SLA batteries, you can solve that by installing a 30-ampere fuse. This will help break the circuit if the flow of current is too much.

Lithium batteries charge four times faster than SLA batteries – a major upgrade if charging your Power Wheels is the main issue. They are also much better at handling high temperatures.

Overall, both batteries have pros and cons that you should evaluate before making a purchase.

How Safe is a Power Wheels Battery Upgrade?

Following the instructions is important as missing a step or two can cause trouble in the system. If you’re not used to handling anything involving circuits, go at a slow pace as things can go wrong if you work at an unfamiliar speed.

Here are some of the things you should do to avoid messing up the setup.

1. Install a Fuse

It doesn’t matter if you’re using a lithium-ion battery or a less powerful sealed lead-acid one, if you’re upgrading a 12-volt Power Wheels to an 18-volt car, the increased voltage will almost always be too much for the ride-on to handle. 

This might cause it to overheat (or even catch fire in some extreme cases).

Luckily, most SLA batteries come with an inbuilt fuse that will help protect the motor (always check as you can never be too sure). You can also add an external 30- or 40-ampere fuse to the lithium-ion battery.

2. Install an Electronic Speed Controller (ESC) Kit

Upgrading the original battery increases speed. This might be a bit dangerous if your children do not have the required motor skills to drive the Power Wheel at an increased speed.

Also, an 18-volt Power Wheel is more powerful than a 12-volt car so it might take some time for them to adjust.

If this is the case, installing a motor speed controller will ensure that you can manually control the voltage transmitted into the motor. You can fix it between your new battery and the motor.

3. Keep an Eye on the Polarity

You’ll need to modify some of the factory wiring during this process, so you have to make sure that your vehicle connections are right. 

An example of this is how you should connect the bigger battery’s positive wire to the smaller battery’s negative wire (and not positive to positive or negative terminal to negative).

4. Make Strong Connections

Avoid having any loose wires in your system as this might affect the functioning of the whole car. If you have any loose connections after the process, solder the joints to avoid future troubles.

5. Secure the New Battery

Whether your kid is driving the Power Wheel or you’re working on it, it might topple over. If it does, the battery should be in such a position that it doesn’t fall out of the hood.

Upgrading Your Power Wheels Battery

Most Power Wheels are 12-volt ride-on cars, so it’s likely that you’re looking to upgrade this particular model. That said, you can also convert a 6-volt Power Wheel into a 12-volt car.

You can make the Power Wheels faster by either creating a battery pack with two 6-volt batteries or by buying a whole new 12-volt replacement battery. The latter, in this case, will be the best option.

This tutorial will specifically focus on upgrading 12-volt cars into 18-volt Power Wheels. To do this, you can either add a 6-volt battery to the 12-volt Power Wheels battery or switch out the 12-volt cell for a new 18-volt battery.

Be aware that increasing the speed might burn out your gears and motors so you should think about replacing them sometime down the line.

Adding a 6-Volt Battery to a 12-Volt Battery

Here are the tools you’ll need to carry out this process:

  • the 6-volt battery;
  • an inline 30-amp removable fuse;
  • a fuse holder;
  • a screwdriver;
  • a jumper wire;
  • wire strippers;
  • crimp connectors; and
  • crimping pliers.

Before doing anything, make sure that the batteries have the same run time/discharge rate i.e., battery capacity divided by the number of hours it takes to charge/discharge the battery. 

You can do this by ensuring that the amp-hour ratings of both batteries are the same. 

Take Out the Battery

The first thing you’ll need to do is remove the 12-volt battery from the engine compartment at the front of the car. Take out the battery connector and unscrew the cover shielding the motor.

Completely remove the hood and take out the old battery.

Wire the Two Batteries Together

You need to do this in a series circuit and not a parallel one.

A series combines voltage (6+12) whereby there will only be one path for the current to flow. With a series circuit, you won’t be able to use the same charger if you’re joining two batteries with similar volts (12+12 or 6+6).

As already mentioned in the polarity section, you’ll need to connect the positive terminal of the large battery to the negative terminal of the smaller one. 

You don’t need to do this, but for a more effective connection, take your jumper cable and fit a terminal ring on one end and a female spade terminal to connect the terminals.

Connect the Fuse

This should go onto the positive terminal of the 6-volt battery.

Connect the holder and follow it up with the 30-amp fuse. With your bullet connectors, connect the two open terminals to the vehicle. 

Fit the Battery Pack

Once done, take your battery pack and fit it into your Power Wheel. Make sure it’s the correct size when fitting it into the compartment.

Cut out some of the plastic if the pack is too big to fit in. Watch out for the motor while doing this.

You can also choose to install some heat sinks on the motor for proper heat regulation.

Test It Out

Once done, confirm that the battery is not loose.

If it’s well-placed in the newly cut cavity, take the Power Wheels out for a test drive. Do this at a lower speed first then press on the gear to gradually increase speed.

Replacing the 12-Volt Battery With an 18-Volt Drill Battery

Replacing a 12-volt battery with an 18-volt cell is the most efficient way to modify Power Wheels to a higher battery capacity.

In this case, though, we’ll get our new motor from a Milwaukee drill. You’ll need to use a USB battery adaptor to modify its connection points before starting the process.

Using the USB Adaptor

Although there are several ways for you to hook the battery to the Power Wheels, this is by far the easiest. Pop open the adaptor and locate the battery connection points.

Turn it over and hook two wires onto the connection points. Finish this up by drilling a couple of holes into the plastic for the wires to go through.

How to Modify Power Wheels to an 18-Volt Battery

Here are the materials you’ll need for this process:

  • the 18-volt battery;
  • a fuse holder and a 30-amp fuse;
  • wire cutters;
  • a flathead screwdriver;
  • electrical tape;
  • crimping pliers; and
  • wire stripper.

Connect the Fuse

The first thing you’ll need to do is hook the fuse to the positive side of the wire. Because the Power Wheel connector will most likely not match the new battery, you’ll need to cut it off.

Attach the Battery

After this, attach the plastic to the Power Wheel by drilling a couple more holes into it and screwing it onto the side of the battery cavity. Slide your battery onto it.

Connect the Speed Controller

To hook it to the car, link the motor to the “motor section” and the battery to the “input section.” 

Use your electric tape to stick it onto the compartment.

Test It Out

In the end, this setup is a lot simpler than the previous one. You’ll also have some space inside the battery cavity compared to when you needed to cut out some of the plastic.

When done, take the ride-on car out for a test drive (both with and without extra weight i.e., the kids).


Before modifying your kids’ Power Wheels car, make sure that you’re comfortable with the process. It’s not that hard and with a bit of confidence, you’ll be done in a few hours.

Overall, upgrading the stock batteries is miles better than buying a new ride-on. You’ll also get to sharpen your technical skills while you’re at it.

It’s a win-win for everyone!