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RC Car Batteries (The Ultimate Guide for Beginners)

Most RC Cars come with the batteries included. However, for a new RC Car purchaser, it can be difficult to know if you really have the best battery for your type of vehicle or if you should upgrade.

How many different types of RC Car Batteries are there? There are 5 types of RC batteries that you can purchase: alkaline, nickel-cadmium (NiCad), nickel-metal hydride (Ni-MH), Lithium ion polymer (LiPo), and high voltage lithium polymer (LiHV). These are available as packs or singles.

Knowing how these batteries work and when to use each type can help your car run more smoothly. Some batteries can give your car an impressive boost, while others are simpler and safer. The following information will help you make an educated decision about what kind of RC battery is right for you.

The Inner Workings of a Battery

Batteries are devices that use chemical reactions to produce electricity. Most batteries power devices using the same basic system.

The main difference between types of batteries are the types of metal that encase the battery, the kind of metal at the center of the battery, and the chemicals that are used in the paste that fills the battery.

In a basic battery, the outer metallic case of the battery is the negative electrode and is usually made of zinc.

It houses electrons and provides the source of energy. The point at which it connects to the negative terminal is called the anode (-). When the anode is hooked to a negative terminal on an external device, the electrons travel into the device and through it to exit out of the external device’s positive terminal.

This is when the battery’s positive terminal (+), which is called the cathode, comes into play. The cathode is typically made out of carbon. This is the part that sticks out of the top of the battery and actually is covering a column of carbon that sits at the center of the battery.

In between the zinc exterior and the carbon interior there is a separator that acts as an insulated casing. It sits just inside the exterior casing and is usually made of cardboard or paper.

It keeps the two charges separated and holds in the paste that fills the remaining space inside the battery. This electrolyte paste provides the mixture for chemical reactions.

When the electrons travel from the anode to the cathode, they cause chemical reactions to occur at each end of the battery. The anode’s reaction is a process called oxidation, where two or more ions (electrically charged molecules or atoms) form a compound with the anode.

This causes electrons to be released.  When the electrons reach the cathode, they are added to the cathode material and free electrons from the paste to create more compounds. This reaction is called reduction. Occurring simultaneously, these two reactions cause electricity to flow.

Eventually, the cathode or anode run out of material for reactions, resulting in the death of the battery.

Alkaline

We won’t spend too much time on this battery, because it really isn’t suited for RC cars. Alkaline batteries are usually single-use batteries and are intended for devices that don’t require a lot of power, like remote controls or flashlights.

Using alkaline batteries in your RC cars quickly becomes costly as they only last for a short time and, although some are rechargeable, they lose their ability to recharge rather quickly.

Nickel-cadmium (NiCad or NiCd)

The NiCad battery uses nickel oxide hydroxide and metallic cadmium as electrodes. NiCad batteries are an older, durable technology. These batteries were originally wet-cell batteries and were invented in 1899.

They discharge 1.2 volts at terminal voltage. These batteries were once widely used by RC hobbyists, but the community’s attention has been mostly usurped by the next two types I’m going to discuss.

NiCad batteries do have a few advantages. They are reliable and good for beginning drivers. They are very inexpensive and are available as a rechargeable battery. They expel their maximum voltage for the entire time that they run and do well at low-temperatures.

Unfortunately, they also have some issues, especially when they have the capability to recharge. These batteries actually develop “memory.” For example, if your battery isn’t quite dead and still has 30% of its charge left, and you decide to charge it the remaining 70%, the battery will ‘remember’ that it charged 70% and will only charge to that level next time, even if the battery is completely run down.

This means that every time you charge it, it might charge less and less of the battery. In order to counteract this, many racers will let it run all the way down so that it retains its ability charge to 100% of its potential every time. These batteries are also a little heavier, and they lack the power and capacity of the newer models.

Nickel-metal Hydride (Ni-MH or NiMH)

Ni-MH batteries have been used since 1967 and are a very reliable, safe source of power. Ni-MH batteries use nickel oxide hydroxide, just like the NiCad battery, but instead of cadmium, it utilizes a hydrogen absorbing alloy.

The capacity of a NI-MH battery can be two to three times that of its older rival and some of the newer batteries can have a comparable energy density (the amount of energy that can be stored per volume) to the LiPo battery.

Ni-MH batteries have many advantages. Many inexpensive RC cars come with Ni-MH batteries. A high-end NiMh battery can last for a few hours and is typically durable. They perform well with lower-end cars and are suitable for casual hobbyists, as they are inexpensive and very reliable.

They are available in packs or as single rechargeable batteries. They are known for having lower internal resistance, which makes them ideal for high-current-drain applications. They also recharge fairly quickly (usually within an hour) and can run for a few hours.

Unfortunately, they also have a few disadvantages. If you are a serious racer, NiMh batteries close their charge faster than a LiPo battery. The rechargeable batteries themselves also lose their ability to recharge over time and eventually have to be replaced.

A Ni-MH battery that is used daily can lose up to 20% of its charge a month. Ni-MH batteries also output much less power than a Li-Po battery. In addition, they are greatly affected by higher temperatures.

They do better on colder days and tend to have a longer battery life and a slower discharge when stored at room temperature. However, if exposed or stored at temperatures exceeding 100° F (45° C), they lose their charge three times as fast, so it really isn’t a good idea to leave them in a hot car.

Nickel-metal Hydride batteries are best suited to racers who are more casual. They allow for a few hours of run time and they are safe and durable. They can be damaged by overcharging, so spending a little extra money to buy a quality monitoring charger can be a good investment if you want your batteries to last for a longer period of time.

Lithium Ion Polymer (LiPo, LIP, Li-poly, lithium-poly)

LiPo batteries use a polymer electrolyte instead of a liquid electrolyte. LiPo batteries are the most recent type of battery technology. Researchers have been trying to find a safe way to utilize lithium cells since the 1980s, but were only successfully developed in 1991 into power storage units.

Lithium batteries are commonly found in phones and other smart devices. LiPo batteries can be flat, in which case the different parts of the battery are separated and stored as sheets instead of columns.

However, they can also look nearly identical to the typical, cylindrical batteries. They use lithium and carbon for their electrodes. Lithium is highly reactive, which is both an advantage and a disadvantage.

It contains atomic bonds, which means it has a very high energy density. To compare, a typical LiPo battery can store 150 watt-hours in 1 kilogram of battery, while a typical Ni-MH can only store 60-70 watt-hours at the same size.

Due to these impressive statistics, LiPos have many advantages. Their lightness enables a car to gain extra speed because it has less drag. LiPos only loses about 5% of their charge per month after daily use and, unlike the NiCad battery, they won’t exhibit “recharge memory;” they continue to charge to their full capacity every time you charge them.

LiPo batteries can be charged hundreds of times without losing their ability to recharge. Their power capacity has also been known to allow some RC cars to reach speeds in excess of 100 mph. With those things in mind, why wouldn’t you buy a LiPo battery for your RC car?

Unfortunately, with great power comes great responsibility. LiPo batteries can actually explode or catch fire if damaged. The technology has been improving—albeit somewhat slowly—in the development of more stable products, but these accidents do still occur.

They happen very rarely (like .000003% of the time), but when they do occur, the damage can be devastating. These fires have resulted in the loss of RC cars, property, homes, and even a few deaths. Before you buy a LiPo battery, it is important to know how to safely charge and handle this powerful energy source.

First, it’s important to understand what causes the battery to react this way. Lithium batteries are able to contain a lot of energy. When that energy is provided with a controlled, slow-release, it is very useful. However, if it is released all at once, it can be explosive. Several things can cause this release.

If the separator fails, and the anode and cathode touch, it can cause the battery to begin to overheat. In addition, when exposed to air or heat, the lithium ions inside of the battery will combust and release their energy stores.

This doesn’t usually result in an explosion unless the battery has been charged beyond capacity. The less energy that is remaining in your battery, the less damage it will do when the energy is released. However, even if your battery is just smoking, a damaged LiPo battery will still release an impressive amount of heat which can cause any nearby, flammable objects to ignite.

Luckily, there are many ways to keep your LiPo from reaching that point. Here are a few safety tips that should keep you from becoming that unhappy one in a million:

  • Bring a fire extinguisher with you when you drive your RC car. Although it IS rare, rough handling can puncture the battery and expose the lithium ions to the air.

    When that occurs, a fire extinguisher can keep the situation under control before too much damage is done to the surrounding area.

    You may never need to use it, but incorporate it as part of your racing gear, anyway. Many battery manufacturers have begun to integrate protective layers of fiberglass onto both sides of the battery, in order to prevent any damage to the actual battery. Still, it doesn’t hurt to have the extinguisher, just in case.

  • Don’t overcharge your battery. Using the wrong type of charger can force more voltage into the battery than it was designed for. That can cause a chemical reaction where the ions will heat up and, if not discontinued, will be forced to release their built-up energy.

    This is usually what will cause an actual explosion. Not only is it hot, but more energy than would normally be stored within the battery is forced out all at once.

    There are videos on YouTube of people doing this on purpose, but please don’t try it. Not only is it a waste of an expensive battery, but it can damage property and people.

  • Before you plug your LiPo into your vehicle for the first time, make sure the electrical system of your vehicle is working properly.

    Check for loose or exposed wires. Anything that can cause the positive and negative electrodes to cross will cause heat to build up and will permanently damage your batteries.

    If the crossed wires continue to touch, eventually one or more of the LiPo batteries within your vehicle will rupture, which will cause smoke or fireballs.

  • In contrast with the Ni-MH, which simply loses its charge three times as fast in hot temperatures, exposing your LiPo battery to excessive heat can cause the battery to swell as it overheats.

    This will either ruin you expensive LiPo battery or cause the battery to ignite. Anything that causes the battery cells to rupture will result in a release of energy.

  • Store your LiPo battery in a LiPo storage case. They often come with a small storage charger that prevents your battery from fully discharging. If the LiPo does fully discharge, it will be useless.

    Unlike the NiCad, they don’t have memory and can be recharged at any charge level without damaging how far it can recharge the next time, so it is better to recharge your battery before it gets to zero.

LiPos do have a few other issues, as well. They do age, even without use, so storing them for years isn’t really advantageous.

Their higher power ability also makes them harder to handle; they usually come with more sophisticated controllers that are more difficult to operate. They and their chargers can also be expensive to buy, though these costs are mitigated by the long life of the battery.

LiPo batteries are best suited for more advanced RC cars and drivers. The main thing to remember about LiPos is that they have been safely handled by millions of people over the years.

Most likely, many of your own devices already contain them, maybe even without your knowledge. Following our tips should eliminate any potential problems.

In most regards, the LiPo is the best power source on the market and will give you a much better chance of winning your races or helping your car to reach its full potential.

High Voltage Lithium Polymer (LiHV or HVLi)

New to the market, the LiHV is essentially a LiPo battery that is capable of charging to a higher voltage safely. There isn’t much known about the long-term abilities of the battery, but here is some information I was able to gather.

LiHV batteries are smaller and lighter, due to their higher energy per weight capabilities. They are able to charge to 4.35V per cell. In comparison, this level of energy storage would be dangerously high on a regular LiPo and could cause combustion.

In the LiHV, this increased voltage should enable your car to move faster. It is lighter, which can also decrease energy output, providing for longer racing times.

Currently, the LiHV batteries seem to have a fairly short life cycle. After only 30-40 recharge cycles, the batteries begin to swell and lose the ability to hold a full charge.

Like their older lithium counterparts, they can also get overheated. For day-to-day activity, they are a pretty expensive battery, and may only last for about a month, but if you want to save them for racing, their improved performance can be beneficial for that.

Battery Packs vs Single Rechargeable Batteries

Rechargeable batteries can be sold individually, or as a pack. Some people prefer to recharge their vehicles batteries by using a regular type of battery charger so they don’t have to purchase new equipment.

Some RC cars come with battery packs already installed, though many of the lower end vehicles don’t come with any batteries at all, just a place for inserting individual batteries.

I have personally found that the individual batteries don’t seem to last as long as battery packs. In my opinion, packs are far superior, and anyone who wants to run their vehicle for a couple hours at a time should invest in buying one.

Even if your vehicle comes with individual battery slots, a battery pack will work for your vehicle. Simply go to your local RC hobby store if you have one, or browse online. You should be able to find a compatible battery pack without much difficulty.

If, after reading the above sections, you’re considering purchasing a Ni-Mh battery pack, it is worth noting that most of these come with a Tamiya connecter.

You simply have to open the bottom of your vehicle, unscrew the battery case that is located inside, and separate the case from the car by pushing the lever on the white connector and pulling it apart.

Charge your new battery pack and then insert the battery pack’s connector into the car’s connector. Unfortunately, the Tamiya connector is sometimes capable of being connected upside down.

They are keyed to go in the right direction, so if it is difficult to connect, you probably are trying to connect it the wrong way. Once the connector has clicked into place, put the pack inside your car and close the battery compartment’s door. Your car should now run.

Once the battery runs down, simply release the connector and plug it into its charging connector that comes with the battery pack.

If you’ve chosen to purchase a LiPo battery pack instead, these usually have a Deans/T connector. The process is the same for removing the current battery case, after which you simply connect the LiPo connector into the vehicle.

Related Questions:

What is the difference between a dry-cell and a wet-cell battery?  In a dry-cell battery, the paste that is used contains very little moisture. Conversely, a wet-cell battery, as indicated by its name, uses a liquid to contain its electrolytes.

Wet cells use only the anode and cathode as they perform electrolysis. Dry-cells, because of their lack of internal moisture, use “neutral plates,” instead, to increase the amount of oxyhydrogen (HHO) that is produced. The dry cells use HHO to power their electrolysis.

Most batteries that are produced now are dry cell batteries. They don’t carry the same kind of risk of battery acid leaking and, though a little more expensive, are lighter. Dry cells are also more durable.

All batteries that you would use for your RC car will be dry batteries. Wet-cell batteries tend to most commonly be used in automobiles.

Which battery is best for brushless vs. brushed RC cars?  There really isn’t a “best” type of battery. LiPo and Ni-MH are definitely the better batteries, and, depending on what you want your battery to do, are compatible with brushed or brushless RC cars.

However, brushed cars tend to have simpler transmitters and are generally slower and easier to control. While LiPos can be inserted, it isn’t always worth the money. Brushed cars are inexpensive and reliable, but are also limited by their motors’ capabilities.

Ni-MH batteries are, therefore, probably more suitable for a brushed vehicle. In professional racing, where a LiPo battery would really be needed, a brushed car wouldn’t be able to utilize a LiPo to its full potential. In light of this, buying a cheaper and safer Ni-MH pack would give you plenty of power.

On the other hand, a LiPo battery inserted into a brushless vehicle can cause miracles to occur. These are the cars that have exceeded 100 mph.

On a flat race track, you can’t beat this combination. However, the brushless vehicles are more difficult to master for beginners and, unless you need your car to professionally race at very fast speeds, a Ni-MH battery can be suitable for a brushless vehicle as well.

What do the numbers mean on the battery label? Most batteries have two important numbers on their labels. The first important number ends with a “V”. This stands for volts. Individual batteries often have 1.2V, while battery packs tend to be closer to 7.2V (as a total… this is not per cell).

The higher the voltage, the more energy the battery is capable of releasing at one time. This doesn’t affect how long the battery runs… it only affects how much power it is able to dish out.

The other number usually ends in mAh, which stands for milliamp hours. In other words, these letters represent the total amount of energy that the battery is capable of storing at one time.

The higher the mAh, the longer the battery will last. Many Ni-MH battery packs have around 1800 mAh, while LiPos run closer to 4200 mAh.

The bigger the numbers, the longer your car will run and the more it will produce. If you want your car to run faster, a more powerful battery is preferable. The higher power will also increase the speed at which your car can race.

How do I buy the right battery pack?

Occasionally, people purchase battery packs that have the wrong dimensions for their vehicle. The easiest way to protect against this is to measure the dimensions of your battery tray. The pack should fit in the space that the tray used to occupy.

If you’re shopping through an online distributor, you can often look up your vehicle and, under the “frequently bought together” section, they’ll often have the right kind of battery pack.

If you are shopping at your standard RC hobby store, ask for assistance if you don’t have the dimensions. Usually, if you can tell them the manufacturer of your vehicle and your vehicle type, they will be able to assist you in buying the proper pack.

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