Batteries in Model Building

Perhaps the most important part of the RC model building hobby are your batteries. Without batteries, your model won't work at all. In recent years, there have been many new developments in the field of batteries, with the most significant innovation being LiPo batteries. This new technology has not only changed our hobby but the entire world. Batteries are more compact and powerful than ever, and we will see many more exciting developments in the future!


What should I look for when purchasing a battery for my remote-controlled car?

Not only are dimensions important to ensure the battery fits in your model, but also the correct connector and power of the battery. Connectors come in many types, and while a few years ago we could tell which type it was by the color, this is unfortunately no longer so obvious nowadays. Therefore, it's important to check which connector type your model uses, which can vary by brand and often even by car type.

In addition to dimensions and connector, the battery type, capacity, and C rating are important to select the right battery for your remote-controlled model! In the manual of the model or on our website, you often find tips on which batteries are suitable for a specific model. Always follow the manufacturer's instructions for using the correct battery. If in doubt, feel free to contact us directly; we can always assist you.


What types of batteries are there?

Batteries come not only in a wide variety of sizes but also in many types. The most well-known batteries are NiCD, NiMH, Li-Ion, LiPo, and PB (Lead). Each battery has its pros and cons and can be used for multiple applications.


NiCD / NiMH:

The well-known round cell batteries – who did not grow up with them? These batteries started as NiCD (Nickel Cadmium), but this technology has been banned for some years due to the use of prohibited materials. The successor NiMH (Nickel Metal Hydride) has been the standard for many years. NiMH batteries are user-friendly and can take a beating. However, they are limited in maximum capacity and have a relatively low discharge rate.


LI-Ion/ LiPO/ LifePo:

These batteries are all based on lithium technology, which you encounter nowadays in all kinds of products, such as your laptop, smartphone, electric car, and many more. In many attributes, the three batteries share great similarities; however, there are also clear differences between these types of batteries. One thing they all have in common, they can't handle being fully discharged or overcharged; this causes immediate damage to the battery!

  • Li-Ion batteries are primarily found in entry-level RC cars and toy models. They are round cells that come in various sizes. These batteries often have extra protections that intervene during overcharging because Li-Ion batteries especially are suited for small models due to the limited C value of the battery. They can often only deliver a maximum of 10C.
  • LiPo batteries you will encounter most nowadays, especially in larger RC cars such as the Traxxas X-MAXX, ARRMA Kraton, and faster cars like the ARRMA Limitless. But as these batteries become cheaper, they are rapidly gaining popularity. Also, the advent of better chargers has improved reliability, leading more entry-level models to switch to LiPo batteries. LiPo batteries are extremely powerful yet compact and lightweight, making them the ideal battery in many aspects. However, they are more sensitive to incorrect use and, like any battery, need to be handled with care.
  • LifePo batteries are mainly found as transmitter batteries. They have the benefits of NiMH batteries, making them less sensitive to misuse, yet have the lightweight and compactness of a LiPo battery. However, they cannot deliver a high current due to their low C Value.


PB (Lead)


Besides their use as starter batteries in real cars, they are still widely used in model building ships. The advantage is that the battery is relatively inexpensive, although that is starting to change as other batteries become cheaper. But it saves especially the addition of lead to get a ship to the waterline. However, lead batteries cannot be charged or discharged quickly, so quickly charging the battery again is unfortunately not an option, and it takes between 6 to 12 hours.


What voltage does a battery have?

In model building, we almost always speak of nominal voltage. However, a charged battery can often provide a much higher voltage. This also often causes confusion among new model builders. Therefore, below is a short table with the minimum, nominal, and maximum battery voltage for the most common battery types. Thus, be aware that the number of cells can affect the total voltage of the battery.

Type of Battery

Nom. Voltage

Max. Voltage

Min. Voltage

NiCD / NiMH ( 6 cells)

7,2V

10-12V

5,4V

LiPo (2 Cells)

7,4V

8,4V*

6V*

Li-Ion (2 Cells)

7,2-7,4V

8,4V*

6V*

Lood Accu (6 Cells)

12V

14-16V

5,4V

*These batteries may not exceed there maximum or minimum voltage, this will damage the batteries!

Capacity

The capacity of a battery essentially indicates how much energy it holds. The higher this value, the longer you can drive your model. With batteries from well-known brands such as Gens Ace, SMC Racing, X-Cell, you can assume that the stated capacity is correct within a tolerance of +/- 10%. However, we also see many Chinese batteries that promise the best values, and in practice, these almost always turn out to be fairy tales. If the big brands can't fit more capacity into a certain size, then you know for sure that it's technically not possible. Such false values can lead to dangerous situations that can end very badly, so always be cautious with batteries!

Determining exact run time is, however, much harder than it seems. If you can drive for 12 minutes with a 3000mAh battery, you can roughly say that with a 6000mAh you will drive about 22-23 minutes. Why not just double, you might think? Because a larger battery also weighs more, which leads to higher consumption. A good balance between capacity and weight is therefore just as important. Especially with boats and airplanes, the weight of the battery may even be more crucial than the capacity of the battery.


C-Rating: myth or fact?

All experienced model builders know immediately what this refers to. Manufacturers throw around C-ratings as if they're some kind of magic. The C-value is technically the most important number of the battery. It stands for the maximum power that the battery could theoretically deliver. Nowadays, you see LiPo batteries with a C rating of up to 250C. This is, of course, extreme and requires very special compositions. What SMC racing batteries do have, for example. However, many cheaper brands try to ride on these specifications and also apply high values to their batteries, although they often don't even come close to them. The C-value myth has unfortunately arisen because many brands were purely marketing against each other on who had the strongest battery rather than coming from real performance. Fortunately, modern LiPo batteries are now so strong that almost all of them can provide enough power for normal remote-controlled cars.

Let's take an example of a 3S LiPo battery with 5000mAh capacity and a C value of 60A. This battery is very commonly used in 1/10 cars and as a set of 2 for the 1/8 models such as the Traxxas Sledge/ ARRMA Kraton/ Team Corally Radix.

C Value * Capacity in Ah = Discharge Current

With this formula and our example battery, we come to 60*5 Ah = 300A. If we then look in the table below, we see that most cars ask only 100 - 150A from the batteries. So even these modest 60C batteries are more than sufficient.


Model

Power ESC

Accu configuration

Traxxas Rustler 4x4 VXL

80-100 A

1x 3S LiPo 5000mAh

Traxxas Sledge VXL

120 – 180 A

2x 3S LiPo 5000mAh

ARRMA Typhon 3S

85A

1x 3S LiPo 5000mAh

ARRMA Kraton 6S

150A

2x 3S LiPo 5000mAh



But is there a difference between batteries with a high C Value and a low one? Definitely, but for many models, you might not notice the difference immediately. A high C value not only allows for more peak power but often also indicates a lower voltage dip when a lot of power is drawn. So higher C ratings provide additional benefits, especially in configurations with extreme motors and controllers. The world's strongest batteries are the SMC Racing SRD V3 with a C Value of 250C at 10600mAh, theoretically delivering 2650 A, which is about 20 times more than what a standard RC car requires. However, for the speedrun and drag race model building market, these batteries are a real must-have.

Our advice is to choose a battery that always delivers at least 40% more than what your model requires so that you're sure of a safe margin even as your battery begins to age.


Connectors and Their Characteristics

Up until a few years ago, the color of the connector indicated what type of connector it was, leaving you with just 2 or 3 sizes. XT connectors were always yellow, and EC connectors were always blue. Unfortunately, in order to give batteries their own look, manufacturers have switched to their colors of connectors (Gens Ace has yellow EC5 connectors, SMC-Racing black EC5), which led to this beautiful system's loss. Also, many manufacturers have created their unique derivative connector with slightly different specifications.


Brand

Model

Battery

Connector

ARRMA

Boost/ Mega

NiMH / 2S LiPo

IC3 (EC3)

 

Brushless Modellen

3S – 8S LiPo

IC5 (EC5)

LOSI

Mini-T/ Mini-B

NiMH / 2S Lipo

IC2 (EC2)

 

Brushless

3-8S LiPo

IC5 (EC5)

Traxxas

Alle modellen

NiMH/ 2-8S LiPO

TRX LiveID

Team Corally

1/10

NiMH/ 2-3S LiPO

Deans (T-Plug)

 

1/8 – 1/7 Modellen

3-6S LiPo

XT90

*IC connectors are compatabel with regular EC5 connectors.



Charging Batteries: What Should I Pay Attention To?

Charging a battery for the first time can obviously be a bit daunting. Fortunately, we have a few simple rules which make charging any battery straightforward.

  • What type of battery do I have? Every battery specifies what type of battery it is. Often this is prominently labeled on the battery, or else in the specifications on the back. To choose the correct charging program, it's important that your charger settings match the type of battery you are using. If there is an extra, smaller connector next to the main one, then you can almost be certain that it's a LiPo or Li-Ion battery. But always refer to the specifications written on the battery.

  • How many cells? For NiMH batteries, the charger can determine the number of cells by itself through the measurements it performs and you only need to set the charge current. For LiPo batteries, the charger always asks for confirmation of cell count which you can find on the packaging of the battery. But you can also tell by the number of wires on the small balance connector. The number of wires minus one is the number of cells your battery has. When charging, it's important that both connectors are plugged into the charger. Only this way can the charger accurately measure your battery during charging and most chargers will not even start without this balance connector.

  • The maximum charge current is determined by the type and size of the battery. Larger NiMH (sub-c) and LiPo batteries with regular connectors can almost always be charged with 1C. This means that you can charge with a maximum of 1x the Capacity of the battery. For a 5000mAh battery, the charge current is thus a maximum of 5.000mAh which equals 5A. However, we always suggest staying about 20% below this to ensure longer battery life, although this means slightly longer charging times. For smaller batteries or lead batteries, charge current is often just 0.1 or 0.2C and this will be marked on the respective battery.

  • Discharging the battery? With modern batteries, discharging of NiMH batteries is no longer necessary as they no longer suffer from a memory effect. Actually, discharging of batteries is almost never done unless you want to test how much energy is truly inside.

  • Balance charging? This option is found on better LiPo chargers and ensures that your battery remains in the best condition. Charging takes longer than normal because each cell is also independently balance-charged. With a good battery, this is only a few minutes more charging time but as the battery ages and degrades, this process can take longer.

  • Storage option, for LiPo batteries it's important that if they are not used for more than 4 weeks, the batteries should be stored in storage mode. This is about 70% of the battery's capacity and ensures that the battery can be stored for a long time without issues. No battery should ever be completely depleted! But with LiPo batteries, it's also important that they are stored at the right voltage. This way you can enjoy your expensive batteries for the longest time.


Common Mistakes!

So, are batteries that dangerous? Ultimately, every battery is a compact box that holds a lot of energy. It is often said that LiPo batteries are extremely dangerous but ultimately, every battery is dangerous if misused. With the modern batteries, accidents thankfully occur less often, but it's still important to ensure that your batteries are treated properly to prevent problems.


  • My model has crashed and my battery is damaged; I can still use it as long as it works, right? Unfortunately, NO. Especially with LiPo batteries, the damage can be difficult to see as they are packed in multiple layers of foil. If one of these layers is damaged, it can lead to leakage within the battery and the substance lithium can react extremely violently with water and moisture. So do not take risks with your batteries!

  • My charger is giving error messages; what should I do? Make sure you understand what the error message means and look for the cause. Continuously starting the charge process while the charger keeps shutting down can lead to dangerous conditions. If the battery gets too hot or is overcharged, it may catch fire.

  • Multiple batteries go into my model; can I mix them? Only identical batteries can be used together. If there is a difference in capacity or C rating, this leads to problems because one of the batteries will be depleted before the other, damaging the empty battery. So never use different batteries together in your model. The advice is even to ensure that batteries stay together so that age and usage are identical.

  • My LiPo battery is deeply discharged; what now? Unfortunately, this is something we still see happening. LiPo batteries should never be fully discharged as this can cause internal damage. If the battery is just barely too low, they can often still be restored, but always seek the advice of someone experienced in these matters.


Which Batteries Really Fit in My Model?

With such a large selection of various batteries, it's virtually impossible to tell at a glance whether a specific battery will fit particular models. However, for the most popular cars, we have created a simple list so that you quickly choose the right batteries for your RC car, boat, or truck. For many models, we also offer combo deals that get you ready to start in this hobby!



ARRMA Gorgon & Boost/Mega Granite/ Vorteks/ Senton/ Typhon

ARRMA 3S Vorteks/ Granite/ Senton/ Typhon

ARRMA 4S Kraton/ Outcast

ARRMA 6S Kraton/ Outcast / Notorious

ARRMA 6S Talion/ Typhon

ARRMA Kraton/ Outcast 8S

LOSI Mini-T / Mini-B:

Tamiya Auto 1/10:

Tamiya Truck:

Tamiya Tank:

Team Corally Mammoth/ Moxoo/ Triton:

Team Corally Radix, Kronos, Asuga, Kamaga:

Traxxas Bandit/ Rustler/ Slash/ Stampede XL5 2WD:

Traxxas Bandit/ Rustler/ Slash/ Stampede VXL 2WD:

Traxxas Rustler/ Slash/ Stampede BL-2S 4WD:

Traxxas Rustler/ Slash/ HOSS VXL 4WD:

Traxxas MAXX V2:

Traxxas E-Revo / Sledge / UDR:

Traxxas X-MAXX / XRT: