Lipo vs Nimh batteries
Lipo batteries
Lithium polymer batteries, also known as LiPo batteries, are now used in many consumer electronic devices. They have become very popular in model making thanks to their small size, light weight, and high performance. However, they do have some disadvantages, such as their fragility and relatively short lifespan (between 150 and 250 charge cycles).
Nimh batteries
Lighter and more powerful than NiCd batteries, Nimh batteries are commonly used in model making. They are less dangerous, with virtually no risk of fire, and are therefore more suitable for children. However, they are also heavier and limited in size, with poorer performance than Lipo batteries.
What do the numbers on a Lipo battery mean?
The numbers on Lipo batteries indicate their properties. There are three markings that you absolutely must understand in order to know if the battery is suitable for your radio-controlled vehicle.
The voltage
A Lipo cell has a voltage of 3.7 V (or 3.8 V in the case of HV batteries). You will often find higher values, such as on the battery above: 14.8 V means that there are four cells connected in series car and the voltage is added together. In the world of model making, you will often find 2S batteries to indicate the presence of 2 cells, 3S batteries for 3 cells, 4S batteries for 4 cells, and so on.
The battery voltage affects the speed of the electric motor, so it will determine the speed of your radio-controlled vehicle. For motors, the power is measured in kV (kilovolts per volt). For example, a motor with a power rating of 3,500 kV will rotate at 3,500 rpm for each volt, so with a 2S Lipo battery it will rotate at 25,900 rpm, with a 3S battery at 38,850 rpm, etc.
To help you, here is a small summary table:
| Designation | Number of cells | Voltage |
| 1S | 1 | 3.7 V |
| 2S | 2 | 7.4 V |
| 3S | 3 | 11.1 V |
| 4S | 4 | 14.8 V |
| 5S | 5 | 18.5 V |
| 6S | 6 | 22.2 V |
| 7S | 7 | 25.9 V |
Capacity
A battery's capacity determines how long you can use it before it runs out of power. It is expressed in milliampere hours (mAh). The higher the value, the greaterthe range of the electric vehicle. In model making, the average is 5000 mAh, but some batteries can go up to 12000 mAh. However, a high-capacity battery is heavier and bulkier than its counterparts (be sure to check the dimensions of the battery to make sure it fits in your vehicle).
The discharge rate
The C value is the maximum safe continuous discharge capacity of your battery. For example, on the battery above, 50C means you can discharge the battery at a power up to 50 times the battery capacity continuously, i.e., 6000 mAh 50C = 6A x 50 = 300A maximum continuous discharge. Exceeding the maximum continuous discharge can, at best, cause the battery to deteriorate more quickly and, at worst, cause the battery to catch fire. Always choose a discharge rate well above your maximum continuous discharge car, which may vary depending on the type of terrain, tire size, or vehicle weight.
How do I take care of my Lipo battery?
Precautions to take
Lipo batteries offer power and autonomy to model enthusiasts, but these advantages come at a price. If a Lipo battery is damaged, lithium is highly reactive when in contact with water or moisture, which can cause toxic gas emissions and fire. However, this type of battery is not dangerous as long as you follow certain safety guidelines.
- Immediately dispose of any Lipo battery that has started to swell, is damaged, or has been punctured by taking it to an approved hazardous waste disposal center.
- Do not attempt to repair a damaged battery.
- After a crash, remove your battery, place it in a safe area (away from any flammable materials), and observe it for 30 minutes, keeping a safe distance. After this time, if the battery appears stable, has not leaked, and shows no signs of damage, you can use it again, but remain vigilant.
- Do not leave the battery in a vehicle or directly exposed to sunlight.
- If your Lipo battery catches fire, do not extinguish the fire with water; use sand or an electrical fire extinguisher instead.
Charger a Lipo battery
New Lipo batteries are always charged to 40% of their total capacity car for manufacturers, this is the best way to store them for long periods of time. An initial charge is therefore necessary before use. Do not use the Fast Charge function during the first few charging cycles and do not use a battery that is less than 50% charged. This is to preserve their life and performance. In general, Lipo batteries should never be discharged below 3 volts per cell, as this may damage them.
Before charging a Lipo battery, remove it from the radio-controlled vehicle and inspect it to ensure that it is not deformed or cut. You must use a charger specifically designed for Lipo batteries and never place it on a flammable surface (carpet, wood, etc.) or inside a vehicle with the engine running. You must also monitor the battery throughout the charging process.
Storing a Lipo battery
The ideal place to store your batteries Lipo should be stored in a well-ventilated, cool, dry place at a temperature between 5°C and 27°C. Batteries should be stored at half charge (approximately 3.8 volts per cell): modern chargers have a "storage" function to obtain the voltage storage voltage. During transport, the ambient temperature must be between 5°C and 50°C, away from direct sunlight. You can also use a fireproof bag to store or charge your Lipo batteries to prevent accidents.
