Lipo batteries are no longer too strange for model players in general and airplanes in particular, and it is the primary energy source used in most electric-powered models. To better understand Lipo batteries, the following article will provide you with relevant information as well as guide you to use Lipo batteries properly.
Lithium Polymer is the full name of a Lipo battery, a rechargeable battery that uses a polymer electrolyte instead of a liquid. Lipo batteries significantly impact the formation and development of electric models, especially aircraft models. Furthermore, Lipo batteries are also used in many consumer electronics because of providing higher quality than other lithium batteries. Therefore, Lipo batteries are suitable for those who need long-term use and high capacity.
For Lipo batteries, we need to be interested in three main parameters: voltage, capacity, and discharge.
Lipo batteries are usually two types: series or parallel from one or more cells. Each cell will have a voltage of 3.7 V. Hence, depending on the model, we can choose a large or small voltage corresponding to the appropriate cell number.
If you would like to increase the voltage of the Lipo battery, you should choose the battery cells in series and denote them by S:
- One cell (1S): 3.7 V
- Two cells (2S): 7.4 V
- Three cells(3S): 11.1V
In addition, to increase the battery’s capacity without changing the voltage, the cells will be connected in parallel and marked with the symbol P. For example, a Lipo battery has the symbol 2S2P that will be connected to 2 2S batteries in parallel.
Battery capacity is the amount of energy stored in the battery when fully charged per mAh, and battery capacity corresponds to the maximum current the battery discharges to run for 1 hour. At the same time, the load current also affects the battery operating time and is directly proportional to the operating time. In other words, the battery capacity will determine the active time.
Apart from for model aircraft, a large-capacity battery will be used, corresponding to a large battery capacity and a higher consumer current. Therefore, the battery capacity will not be directly proportional to the flight time, and it is necessary to consider increasing the battery capacity to increase the flight time of the model.
One of the most important aspects of a battery is its discharge, which is understood to be its ability to supply large currents safely. The continuous discharge on a Lipo battery is calculated as a multiple of the battery capacity (C). For example, a battery with a discharge of 10C means you can safely discharge at a rate ten times its power.
Besides, to increase the capacity, you can discharge with a higher current instead of a continuous discharge but only for a short time of a few seconds. Currently, on the market, there are also many different types of discharge lines for you to choose from, but the higher the discharge current, the more expensive it is.
Pros and cons of Lipo batteries
Lipo brings many benefits to users with a wide range of types of batteries, specifically as follows:
- Small, lightweight design with a variety of models and sizes.
- High capacity.
- High discharge while still providing enough power for high-power engines.
In short, Lipo batteries have a high energy storage/unit ratio and fit every model in various sizes and shapes.
Besides the benefits, it also has a few drawbacks:
- Lipo batteries are expensive.
- Flammable and explosive if not stored and used correctly.
- There are many requirements to comply with to ensure longevity and safety.
- Battery life is not high.
To restrict the disadvantages, we should use them properly and follow the usage requirements to help prolong the life of the battery and ensure safety.
Use Lipo battery the proper way
Discharge Lipo battery according to 80% principle
It would be best if you abode by the “80% Rule”, which means it not be discharged more than 80% of its capacity. Therefore, if the Lipo battery is too exhausted and a battery cell’s applied work falls below 3.7 V, it will quickly become hot and damaged.
For instance, if you have a 1000 mAh, you had better only use 800 mAh of the battery (80% x 1000).
However, you should use a battery with a half capacity for high-discharge batteries.
Lipo battery charger
For Lipo batteries, charging is also very substantial, so you must choose the correct charging voltage to avoid damaging and causing a fire. Typically, a battery cell has a voltage of 3.7V at both ends and reaches 4.2V when fully charged, and overcharging this voltage will cause damage and even blaze.
Most current chargers will use the constant current method, which means that the current will not change during charging until the battery voltage is close to 100% of the charging voltage. This charging cycle will end when the battery’s charging voltage equals the charger’s constant voltage of 100%. In particular, the charger’s voltage should not exceed the voltage of the battery even by 0.01, which can also reduce the battery’s life.
Lipo battery balance
As mentioned, one cell (lipo 3.7V) does not need to worry about balance issues because the charger will automatically stop the voltage when it reaches 100% is 4.2V. Nevertheless, for multi-cell Lipo batteries, balancing voltage between the two cells is an important problem because it is difficult to determine.
For example, if we have a 3-cell charger, maybe two new cells charge to 4.2, and the other a little faster and cross the threshold up to 4.5 before the charger stops at 12.6V. Indeed, this will affect the battery cells, and there is a high possibility of fire and explosion.
Voltage difference during charging often occurs with batteries that have been used for a long time, so you should pay attention to check to avoid the risk of fire, explosion, and damage over time. And to solve this situation, you should equip an equalizer for each charge or at least every two charges, which will help preserve the life of the battery and reduce the risk of fire.
The above article has provided information about Lipo batteries, how to use them properly, and some notes about Lipo. Hopefully, this article is helpful to you.