Upgrading Your RC Car Battery: Why, When and How


Upgrading Your RC Car Battery

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When you purchase a radio controlled (RC) car, it will probably come with a basic, no frills battery. The manufacturers of most RC cars are most likely to put a battery with lower performance in their product because they are concerned with the production cost versus profit ratio. Upgrading your RC car’s battery, therefore, is often one of the easiest, cheapest, and most effective ways to increase your car’s performance.

Why, when, and how should you upgrade your RC car battery? Before replacing the battery, check the product’s manual to find information such as what types and voltages of battery your car can handle. Nickel Metal Hydride (NiMH) batteries are most common. Lithium Polymer (LiPo) batteries are lighter and more powerful, but require more care to handle properly. To increase you RC car’s running time, use a battery with a higher milliamp hour (mAh) rating, for more speed use one with more volts (V), and for quicker acceleration (and overall better performance) use a battery with a high C-rating.

Though upgrading your RC car’s battery can be a simple plug and play scenario, there are many different conditions to take into consideration when choosing a new battery. The type of battery, voltage, milliamp hours, C-rating, size, and weight of the battery you want is dependent on the specifications of your RC car, what type of performance you want, and your driving style. It’s also just one way you can upgrade your RC car to get the performance you want.

Types of Batteries

The type of battery that comes pre-installed when you purchase your RC car is designed to be a cheap option that works well enough for casual users. Most often, this will be a Nickel Metal Hydride (NiMH) battery because this type of battery is a good middle ground. It’s durable and offers a good amount of power.

Cheaper cars may come equipped to be run on alkaline batteries, while higher quality models are often either equipped with a Lithium Polymer (LiPo) battery or sold without a battery so the hobbyist can select the battery that best suits their needs.

The different types of batteries offer different pros and cons.

Alkaline Batteries

If you ask most people to imagine a battery, they’ll probably envision an alkaline battery (and it will most likely be a AA battery, at that). While alkaline batteries are ubiquitous, they are not very commonly used to power RC cars, except in the lowest quality models. If your RC car is designed to run on alkaline batteries it will probably not be easy (or worth it) to upgrade the battery. You’ll be better off upgrading to a higher quality RC car as a whole.

Pros:

  • cheap
  • durable
  • easy to find

Cons:

  • (usually) not rechargeable
  • heavy

Nickel Cadmium (NiCd) Batteries

Nickel cadmium (NiCd) batteries are among the earliest types of rechargeable batteries developed. They are cheap and durable, but contain elements that are not good for the environment. They also suffer from memory effect, also known as voltage depression, which is a scenario in which when a nickel cadmium battery isn’t fully discharged before being recharged, it will run for only a fraction of its supposed capacity before running dry.

Because of their negative environmental effects and their poor performance compared to more modern battery technology, most RC car manufacturers have stopped equipping cars with nickel cadmium (NiCd) batteries.

Pros:

  • cheap
  • durable
  • rechargeable

Cons:

  • low power
  • low capacity
  • environmental damage
  • heavy (typically 350 grams)
  • memory effect

Nickel Metal Hydride (NiMH) Batteries

As technology improved over the years, nickel metal hydride (NiMH) batteries were developed as a better alternative to nickel cadmium (NiCd) batteries. NiMH batteries are more environmentally friendly, and are capable of holding a higher capacity than NiCd batteries.

While they do not suffer from memory effect, meaning they can be effectively charged without fully depleting the battery first without reducing the battery’s overall carrying capacity, they are more prone to self discharge than other batteries. This means that a charged NiMH battery will slowly lose its charge over time, even when it is not connected to the RC car itself. Luckily, because NiMH batteries do not suffer from memory effect, you can simply top off the battery before use.

Pros:

  • durable
  • high capacity
  • safe when overcharged
  • more environmentally friendly than NiCd batteries
  • no memory effect problems

Cons:

  • heavy (typically 400 grams)
  • self discharge over time
  • not always as much capacity as advertised

Lithium Polymer (LiPo) Batteries

The most recent advancement in RC car battery technology is the development of the Lithium Polymer (LiPo) Battery. Not only are LiPo batteries able to hold even more power and capacity in a lighter package, but they also do not suffer from the memory effect.

In fact, as opposed to NiCd batteries which should be fully discharged before recharging to prevent memory effect, LiPo batteries should never be fully discharged. Most RC car’s electronic speed controls (ESC) have a cut off feature to prevent over discharging. LiPo batteries also don’t self discharge energy, though they do need to be stored at a reduced charge to prevent damaging the battery.

Special chargers are required for LiPo batteries because they can burst into flames when damaged or overcharged. The special chargers also have settings that charge (or discharge) the cells of the LiPo battery to the recommended level for storage, which prevents the battery from being damaged by sitting for too long at a full charge.

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You can check the charge of each battery cell with a digital battery capacity checker. It is recommended that LiPo batteries are only charged within a fireproof pouch and never left unattended.

Pros:

  • higher capacity
  • higher power
  • light (typically 250 grams)
  • no memory effect
  • no self discharge (when stored at the recommended setting)

Cons:

  • may burst into flames if overcharged or punctured
  • should not be fully discharged
  • should not be stored at full charge
  • not recommended for beginners

Battery Specifications

Even after you’ve picked what type of battery makes sense for your needs, you’ll still be presented with a plethora of options when it comes to the specific ratings of different sized batteries. First, make sure you check your RC car’s manual to find out what battery ratings your RC car can handle.

When picking a battery, it will be crucial to understand what the various ratings written on the battery’s label indicate.

Milliamp Hours (mAh)

Typically written in the largest font on the battery, the milliamp hours (mAh) rating tells you how for how long the battery will run. The mAh rating has no effect on how fast your RC car will go, only how long it will run for. The higher the mAh rating, the longer you can drive your RC car before you need to recharge it. In that sense, it’s akin to how much gas your car can hold.

If you find that your RC car runs out of battery before you grow tired of driving it, you may want to replace the battery with one of the same type and voltage, but with a higher capacity (mAh) rating so you can drive it for as long as you please.

Volts (V)

The battery’s power is measured in volts (V). A battery’s voltage is sort of like an engine’s horsepower rating. It is a measure of how much power the battery can provide. The higher the volts, the more power the battery offers. More power is required to move more weight, so a big RC monster truck is going to require more volts than a lightweight RC race car or buggy. More power (volts) may also be needed if you are driving your RC car in mud, or other less than ideal conditions.

The battery’s voltage can also equate to a higher top speed for your RC car because there is more power to push the car forward. Remember to check your RC car’s manual before installing a battery with a higher voltage because motors are designed to operate between a set range of voltage, and using a battery with a higher voltage rating could damage or ruin the RC car’s motor.

C-Rating (C)

A typical battery package will actually show 2 different C-rating values. The first is the battery’s maximum continuous discharge potential, which is a measurement of how much power the battery can discharge at any given moment. The second C-rating is the battery’s maximum discharge potential, which is the maximum amount of energy the battery can discharge at once. The max discharge C-rating is always twice the value of the continuous discharge C-rating, though this is only truly accurate when the battery is fully charged.

A higher C-rating equates to higher speeds for your RC car because there is more power available at any given moment to push the car forward. Even more so, a higher C-rating means that your RC car will be able to accelerate more quickly because the power is available when the car is starting from a full stop or picking up speed after making a sharp turn.

It is a common misconception that a battery with a higher C-rating will use up its available energy faster than an otherwise similar battery with a lower C-rating. This is not the case because the battery’s C-rating is taken into account when measuring the milliamp hours (mAh) rating. Thus, when comparing 2 batteries with different C-ratings and the same mAh ratings, the one with the higher C-rating will be able to put out more power for the same amount of time that the lower C-rated battery puts out a reduced amount of power.

Additionally, because batteries with higher C-ratings are able to put out more power at any moment, they are not taxed as much as batteries that are struggling to put out the same amount of energy. This means that the higher the C-rating, the less likely the battery is to overheat.

Cell Count (S)

A battery’s cell count is simply a count of how many separate battery cells are put together in one pack. This equates to power in that each battery cell produces a certain amount of voltage, depending on what type of battery cell it is.

A typical, cylindrical nickel cadmium (NiCd) battery, for example, can hold 1.2 to 1.5 volts (V). Batteries connected in a series, increase the voltage in a manner that adds one voltage to the next, so that a 6 cell NiCd battery pack has a voltage of 7.2 volts (V).

A lithium polymer (LiPo) battery cell, on the other hand, can hold 3.3 to 3.7 volts (V). In this way, LiPo batteries can hold more power even while being smaller and lighter than NiCd batteries.

Learn More

Check out the video below to learn all about the batteries in your RC car.

How to Replace Your RC Car’s Battery

Upgrading your RC car’s battery is a relatively straight forward process. It is important, however, to make sure each step is done properly to avoid damaging your RC car (or worse).

  • Remove the cover to see what you’re dealing with. The cover should come off pretty easily with just a few screws at most holding it in place. Once exposed, you can look at the motor, pinion gears, and other aspects that make the car run. The batteries may be mounted open or within a battery tray.

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Once you find the battery, the label will tell you what type it is, as well as its voltage (V), milliamp hours (mAh) rating, C-rating, and how many cells are in the pack. You will also know how much space is available to mount the new battery and what type of connectors your car’s electronic speed controls (ESC) use.Consult the manual of your RC car to find out what battery specifications your car can handle. Motors and electronic speed controls (ESC) are designed to work within a specific range, and overworking them could damage these components. In drastic scenarios, mismatching could result in the battery bursting into flames and burning down your home.

  • Select a battery that is compatible with your RC car and upgrades the component you are interested in improving. A battery with a higher milliamp hours (mAh) rating will run longer. A battery with more volts (V) will have more power. A battery with a higher C-rating will be able to supply more energy at any moment, allowing for faster acceleration.

Pay attention, as well, to the connector type.

Tamiya connectors, for example, are used on the majority of NiMH batteries, but are not compatible with LiPo batteries. The white (or translucent) tamiya connectors are not designed for the high currents of big burst rate LiPo batteries and may overheat and melt if used. Also, keep in mind the size and weight of the battery you choose.

  • Mount the new battery. If the battery you’re upgrading to is the same (or very similar in) size as the original battery, this could be very simple. If your new battery is a different size, you may need to shim or alter the battery tray to accommodate the difference. If there’s a big difference, you may need to get creative. Many hobbyists use velcro straps to secure batteries that don’t fit in the car’s battery tray.

If the new battery is heavier than the old one, this could shift the car’s center of gravity and affect the way it steers and handles. Mounting it between the car’s drive wheels can add a little stability by giving those wheels more traction.

  • Upgrade your battery charger. If you have a standard trickle charger and you replace the battery with one that has twice the capacity, it will take twice as long to charge. Not only will smart chargers repower your batteries faster, they also have other functions that can be critical for certain types of batteries.

Smart chargers are essential for LiPo batteries because they need to be stored at a 50% charge to prevent damage. Smart chargers are able to charge and discharge individual cells within the battery pack to balance it to the appropriate level. It is worth noting, however, that consistently fast charging batteries at high voltages does ultimately shorten the batteries life, so it may be worth holding on to your old trickle charger when you can afford the time to charge it more slowly.

Other Ways to Upgrade Your RC Car

Though certainly the easiest, upgrading your RC car’s battery is only one way to improve its performance. In some cases, upgrading the battery won’t even improve the things your car is struggling with. If your car is spinning out at every hard turn, for example, you probably need to upgrade the tires so that they have more traction. Increasing the power in the battery can only make the tires spin faster and slip even more.

In other cases, you might not be able to upgrade the battery because it is already the maximum voltage that your car’s motor and electronic speed controls (ESC) can handle. In that case, you’ll need to upgrade the battery as well as the motor and ESC.

Here are a few other adjustments you can make to upgrade your RC car to increase its performance.

Adjust the Gear Ratio

There are 2 gears in your RC car that transfers power from the motor to the wheels. By adjusting the size of each of these gears, you can adjust your car’s top speed and acceleration.

  • The pinion gear is attached directly to the motor. It is made of aluminum, steel, or titanium, and comes in many sizes and pitches. As a general rule, the more teeth the pinion has, the faster the top speed of the RC car will be. This does not affect acceleration, just the maximum speed on a straight away. In fact, a smaller pinion gear with fewer teeth will result in quicker acceleration (but a lower top speed).

  • The spur gear is attached to the wheels and is turned by the pinion gear. Increasing the size of the spur gear will increase the acceleration and lower the top speed while decreasing the size will increase the top speed and dampen the acceleration. The effects of altering the spur gear size are less noticeable than adjusting the size of the pinion gear, though both should be adjusted for the best results.

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When adjusting gear sizes, don’t make too big a change at once. Instead, you should increase or reduce the number of gears by only a few at a time and test drive it to check if there is significant temperature change while running at the new gear ratio. If the car is overheating, you may need to drop back to the previous gear ratio. If not, you can test it with a few more gears added (or subtracted).

The proper ratio of top speed versus acceleration power will depend on what course you are racing, and your driving technique. Some courses have a lot of sharp turns, requiring a lot of acceleration, while others offer long straightaways, giving you a chance to take advantage of your car’s top speed. If you’re not racing, the determination may depend on how much space you have to drive around in, and what makes driving your RC car fun for you.

Upgrade the Motor

Most lower end RC cars come equipped with a brushed motor because they are cheaper, more durable, and easier to drive. The brushes convert electricity into motion, but some of the energy is lost to friction. At some point, you’ll want to upgrade to a brushless motor.

Brushless motors are more efficient because they use ball bearings to reduce friction, resulting in an increase in speed. They have more complicated steering, responsiveness, and suspensions, making them harder to drive. They also cost more to purchase and maintain. If you’re serious about RC racing, you’ll most likely want to upgrade to a brushless motor at some point.

Upgrade the Tires

No matter how powerful your RC car’s motor (and the battery powering it) is, your car’s speed and performance ultimately depends on the tires’ ability to grip the road. When the motor spins faster, it turns the pinion gear faster, which turns the spur gear faster, which turn the wheels faster. If the tires don’t have enough traction to push against the road, however, the car isn’t going to move any faster.

If you are driving on roads or tarmac, slick tires will be the best option because most of the tire’s surface area actually comes in contact with the ground. Fully spiked tires are best when driving on slippery grass and mud, while minis pins are best when driving on carpet. A good all-around tire is one with mini spikes because it is effective on many different types of road surfaces.

Not only the quality but also the age of the tire will affect its traction. Tires become more dry and brittle over time. They are less able to squish and conform to the road during the turn, so older tires will grip less as they age.

Larger tires cover more ground per rotation, so larger tires can equate to higher top speeds. They do, however, weigh more, which can counter this effect and also reduce your RC car’s acceleration and handling abilities.

Reduce the Weight

Just like it’s easier to pull an empty wagon than it is to pull a wagon full of rocks, the lighter your RC car is, the easier it is for the motor to produce the high speeds and quick acceleration you’re looking for. RC cars are pretty light, so it can be hard to detect the difference just by holding the car in your hand, but even small reductions in weight can have significant effects on your car’s performance.

Replacing parts with those made of lighter metals, such as graphite, aluminum, or light carbon is a great start. Upgrading to a LiPo battery, which can hold more power while weighing less, is another smart move.

The downside of reducing your RC car’s weight is that this, in turn, reduces the tires’ traction. With less weight pushing the car down toward the ground, the tires make less connection and cannot propel the car forward as effectively. This is less of an issue when on a straightaway, but when making sharp turns, a lighter car will be more likely to roll. This could not only cost you the race, but it could also damage your car.

To counteract this effect, try moving some of the weight (the battery pack, perhaps) between the car’s front wheels.

Conclusion

Upgrading your RC car’s battery is the easiest way to increase its performance. You must, however, make sure to pick a battery that is compatible with your car’s motor and electronic speed controls (ESC) and upgrades the performance aspect that you need. 

There are several modifications you can make to your RC car to improve its performance. Whether you choose to upgrade your motor, lower its weight, change its tires, upgrade the gears, or do all four you are sure to increase your car’s speed and acceleration. 

When you make any upgrades to your car be sure and spend plenty of time practicing with your new upgraded car before you try to race. The increased acceleration and speed can be quite surprising so make sure that you know what you are dealing with so you don’t accidentally damage your newly upgraded car. 

If you are interested in learning more about the batteries in an RC car you can read another article that I wrote about how to make your RC battery last longer here.

Matt Robbs

I love to spend time with my wife and 3 kids. There is no better way to get them off the couch and outside than for us to grab the RC cars or boat and enjoy the sunshine!

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