I’ve used nickel-metal hydride and lithium polymer batteries during the many years I’ve been involved i the RC hobby.
My opinion: The best LiPo battery is so much better than NiMH in terms of low weight and high energy density in RC cars, such as a Traxxas Slash or Summit.
In my rock crawler, I still use NiMH because I like the extra weight from the battery over the front end, but that’s a different story.
Guide to buying a Li-Po battery in 2019
Batteries have a language of their own. When making a purchase, you are confronted with tech specs. Let’s learn how to decipher the code.
The first important characteristics to understand are capacity and voltage.
Typical LiPo batteries use a particular type of labeling to show this.
An example of this is the marking ‘4S-2200’ found on typical batteries.
The ‘4S’ in the example means that the battery has four cells. Generally, each cell has a voltage of 3.7 volts. This shows the total voltage of the battery.
4 cells times 3.7v equals 14.8v.
The second number is the capacity of the battery. It is shown in milliamp-hours or mAh.
A fully charged 2200 mAh battery can give an electric current of 2200 milliamps, or 2.2 amps, for an hour.
The capacity has nothing to do with how many cells are in the series of the battery. It simply allows a user to know how long the battery will give full power.
The RC car user will find that this is very useful to know. It means that they can expect twice as much running time from a LiPo battery marked ‘4S-5000’ than they can one marked ‘4S-2500’.
Series or parallel
Batteries with cells in parallel are rare today. They are marked slightly differently than more common cells in series batteries.
One labeled ‘4S2P-2200’ would be made up of two ‘4S-1100’ batteries wired together to create 2200 mAh capacity. It may be differently sized, but that is all.
The third most important thing to understand is the discharge rate of a battery.
Good LiPo batteries have a limit on how many amps can be output continually without being damaged.
Most RC uses have very high discharge rates. If this is ignored a battery can fail and damage the RC equipment.
A battery’s discharge rate is shown as a multiple of C. C generally means coulombs of charge.
A common discharge rate on a ‘4S-2200’ battery is shown as 20C. To get the maximum discharge rate one multiply the number by C with the second number.
So 20 times 2200 equals 44000 milliamps or 44 amps.
What this means is that this battery is safe to discharge 44 amps or less continuously. It should only be used in a system that can just draw up to 44 amps or it or the RC could be damaged. It can be expected to give its greatest power for only a few minutes.
Most RC vehicles do not draw a continuous amperage. Draw will change depending on what is happening.
RC cars and boats have large draws during fast acceleration. This means that it is unwise to select a battery that barely meets the vehicle’s needs. Instead choose a better battery. Weight is less important with land vehicles, especially when considering how light Li-Po batteries are nowadays.
RC airplanes generally are fitted with a battery that barely meets its needs. They do not generally need as much power as a land craft even during a full-throttle flight. For fliers the weight of a stronger battery is just not worth the hassle.
The next characteristic of a good RC battery is its casing. Many batteries that could work in an RC car have a thin casing.
They are delicate and easily damaged while in use. Using a purpose made RC battery means that the cost may be slightly higher.
The battery will be more sturdily made. RC batteries are made with a heavy hard plastic case that protects the soft insides.
A damaged battery will puff up. It may not fit in the vehicle. It also may leak or explode. A hard cased battery will last longer. It is well worth any extra cost.
The last important thing to understand when shopping for a LiPo is how to charge it safely.
A battery can explode if charged with the wrong equipment. It can also explode if the person who is charging the battery is using the charger incorrectly.
Always use the best quality LiPo charger that can be obtained. This is no place to save money. Be sure to completely read the owner’s manual.
Many good chargers are able to charge several types of battery. Generally each battery type and how to correctly charge it will be clearly marked.
Make sure that the charger can be correctly set for the type of LiPo battery that is to be charged. Small details such as the number of cells are extremely important to get correct. Also, make sure you charger will fit your LiPo battery connectors.
Finally be sure that the charge rate is within the battery’s marked safe charge rate. Writing these details down before hand is wise. Many also use a safe battery charge bag to protect themselves.