Lithium Polymer Battery Ultimate Guide

Lithium battery technology (both lithium polymer (LiPo) and lithium ion (Li-ion)) is quite different from the nickel-cadmium (NiCd) and nickel-hydrogen (NiMH) batteries we commonly use on models.
Before we use lithium power as a source of power for electric flight, there are many things that we should understand. Nothing is more important than safety. No matter which kind of battery we should be careful about them, because they are full of energy when they are fully charged. Lithium batteries have the energy density of **, and they also have many unique features that require us to do more special safety considerations. It is important to understand these safety issues before beginning to explore other aspects of lithium battery.
1. Charging/Safety Important If you are a newcomer to flying, remember to "don't use" lithium polymer batteries. There are no exceptions. Read on to know the reasons for this.
As for other important ones: the method of charging lithium batteries is quite different from the traditional nickel-cadmium and nickel-hydrogen batteries. To charge lithium batteries, you must use a special lithium-ion battery charger specially designed for lithium batteries.
Generally speaking, if the charger can correctly calculate the number of Cell components of the lithium battery (referring to a large lithium battery consisting of several single small lithium batteries), it can be charged with lithium-ion battery (Li-ion). Most of them can also be used to charge lithium polymer batteries. Remember to never charge a lithium battery with a charger that can only be filled with nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) batteries, which is very dangerous. Charging a lithium battery is one of the most dangerous parts when using lithium batteries. When charging a lithium battery, please pay attention to the charging of the lithium battery. It is very important to set the correct charging voltage or the correct number of batteries for the lithium battery charger. If the lithium battery charger is not set, it may cause over-charging of the lithium battery and cause explosion and fire. There have been several fires caused by lithium batteries. Please charge the lithium battery in a responsible manner.
Here are some guidelines for charging and using lithium batteries. Mr. Fred Marks has a good description: "Safety depends on discipline" ~~~ Please don't forget

1. Use a proven lithium battery charger
2. Make sure that you have correctly set the voltage on the lithium battery charger or the number of batteries. If you don't know how to set it, please buy a lithium battery charger that you know how to set it up. Otherwise, don't Use lithium battery to avoid explosion when charging.
3. When charging lithium batteries, someone must be present. Don't charge the lithium battery when no one is present. Someone used to burn the house and the car for this reason. Remember to remember.
4. When charging, please prepare a suitable platform to place your charger and lithium battery to ensure that the lithium battery will not cause any damage and danger due to accidental explosion or fire. It is a good choice to reserve fire space, prepare fire sand (I can also prepare fire extinguishers), fireplaces, etc. (there may be problems with turning over here).
5. Please do not charge with more than 1C of current. I personally caused a fire at home because of this violation.
6. If one of the lithium batteries expands during charging, don't break it when it is still hot. Put the lithium battery in the brine, wait until the defective cell cools down, carefully peel off the outer skin (plastic cover part?) of the lithium battery pack and then put the battery pack back into the brine before safely putting the problematic The lithium battery is thrown into the recycling bin.
7. Very important: When you fly with lithium battery, the lithium battery is placed in the aircraft, perhaps the battery does not appear to be damaged. However, you should always take care to remove the lithium battery from the aircraft, and then let it sit in a safe place for at least 20 minutes to ensure that the lithium battery is really not damaged and no explosion. There are several examples of fires. After the crash occurred, the owner dropped the corpse in the car, and then the damaged lithium battery exploded in the car to burn the entire car.
8. Please charge the lithium battery in an open and ventilated place, because if the lithium battery really ruptures and explodes, dangerous and harmful smoke and substances will leak out of the battery.
9. When you use a lithium battery for flying or charging, please prepare a bucket of sand next to it. It is the most cost-effective way to extinguish the fire with a sand explosion. This is very cheap and necessary.
10. Please understand that these batteries are dangerous. Don’t have the idea that "I won’t touch it, it won’t happen to me." Otherwise, the next person who saves his wife and children in a burning house or car is You, I take this very seriously.

So far we have covered some key themes, and then we are less serious:
2. What is a lithium polymer battery?
Lithium polymer batteries are used in many electronic devices. For example, there are mobile phones, notebook computers, PDAs, and walkmans. However, most of the lithium batteries are not designed to be used in remote control models. We use lithium batteries in remote control models, which are not used in the applications considered for the lithium batteries. Lithium-polymerized batteries are similar to lithium-ion batteries in that the single voltage is usually 3.6V, but unlike lithium-ion batteries, lithium-ion battery cases are usually hard-shell, while lithium-polymer batteries are soft-shelled. A typical lithium polymer battery is a thin rectangular shape and has two protruding points on the upper side, one being a positive electrode and the other being a negative electrode.
The reason we use lithium batteries is that lithium batteries are significantly lighter than nickel-cadmium or nickel-metal hydride batteries, which can make our aircraft fly longer and better.
Three ‧ voltage and battery count calculation:
The characteristics of lithium polymer batteries during charging and discharging are different from those of nickel-cadmium (NiCd) and nickel-hydrogen (NiMH) batteries. When a single lithium battery is fully charged, the voltage is about 4.2V, and the single discharge is complete. The voltage is about 3V. When using a lithium battery, we must keep the voltage of a single lithium battery between 3 and 4.2V. Overcharge and overdischarge will cause damage to the lithium battery. Don't forget to set the cut-off discharge voltage of your electronic transmission to avoid over-discharge of lithium.
If you have used nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) batteries, the voltage of a single nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) battery is 1.2V, while the lithium battery is 3.6V. You must make some conversions. If you used 6 to 7 nickel-cadmium or nickel-hydrogen batteries, you can use two lithium batteries in series to obtain an approximate voltage. If you used 10 to 11 nickel-cadmium or nickel-metal hydride batteries, you can use three lithium batteries in series to obtain an approximate voltage.
Many of the flying friends used 8 nickel-cadmium or nickel-hydrogen batteries, and they were stuck in the choice of two or three lithium batteries connected in series to obtain an approximate voltage. In my experience, the choice of ** should be to first understand the wattage (W) of power used before flying with NiCd or NiMH batteries, and then use lithium batteries, motors, and propellers. In order to obtain a similar power output.
For example: If your previous aircraft used a 400-class motor and used 8 nickel-cadmium or nickel-metal hydride batteries (9.6V), the current was 10 amps during flight. Then you need to lose 9.6X10 = 96 (W) watts per second, so if you use two lithium batteries (7.2V), you may have to change the paddle flow, the current is 13 amps; or use three lithium batteries (10.8V), and paddle flight, let the current be 8.9 amps. Estimation of collocations such as this requires a bit of experience in order to achieve a ** match, but calculating the power output as a benchmark for estimation is a good starting point.
4. Use 3S4P (3 strings and 4) to get the current discharge capability of 10C lithium battery ?
The speed at which the battery is discharged depends on the ** current output that can be supplied instantaneously. The current output is usually estimated using the word C, which stands for (60 minutes / minutes required for the battery to discharge).
For example, 1C means that the battery takes 1 hour (60 minutes) to discharge the power; 2C means that the battery takes 0.5 hours (30 minutes) to discharge the power.
All remote model batteries use "microampere hours" (mah) to calculate the battery capacity. Assuming a battery marked 2000mah, it means that when we use 2000mA (equal to 2 amps) to discharge it, it takes an hour to discharge. How much C is discharged when the battery is in use is related to the capacity of the battery. If a 2000mah battery is discharged at a current of 2 amps, it is a 1C discharge; if it is discharged at a current of 6 amps, it is a 3C discharge (6 A = 6000mA = 2000mA * 3).
The current lithium battery technology can not make lithium batteries have high C-number high-current discharge resistance like nickel-cadmium or nickel-hydrogen batteries, because many lithium battery packs achieve higher instantaneous discharge current capability through parallel connection. When two sets of batteries are connected in parallel to form a larger battery through the positive pole and the negative pole connected to the negative pole, the voltage of the battery is constant and the capacitance is doubled. If you have two 2000mah batteries, if you connect them in parallel, the effect is equivalent to a 4000mah battery pack. This group of 4000mah battery packs has the same discharge C number as the original 2000mah battery, but due to the doubled capacity of the battery, it is assumed that the original 2000mah battery can provide 10 amps of ** current for 5C discharge; The 4000mah battery from the two sets of 2000mah batteries is also 5C discharge, and its ** discharge current is increased to 20 amps. In this way, the lithium battery pack can provide the instantaneous high current output that a single lithium battery cannot provide.
The naming scheme of XSXP makes it easy for us to know how many batteries are connected in series to increase the voltage and how many sets of parallel battery packs are connected in parallel to increase the discharge current. The front "S" stands for series; the latter "P" stands for parallel. Therefore, a 3S4P battery pack consisting of a single 2100mah lithium battery means that it consists of 12 lithium batteries, which has three times the voltage of a single lithium battery and four times the discharge current capability of a single lithium battery. Therefore, if the ** discharge C number of this battery pack is 6C, it means that he is a set of voltages of 10.8V (3*3.6) and provides **50.4 amp discharge current (2100mah * 6C * 4P = 2.1A * 6 * 4 = 50.4 A)
Lithium battery pack.
5. General use tips:

1. Lithium batteries can't perform as they should in cold weather. If you fly in the winter, you can put the battery in the car before using it to get the lithium battery to play its proper performance.
2. Be careful not to overheat the battery. Try to keep the battery temperature at 140~160 degrees Fahrenheit when using it to keep your lithium battery a little longer.
3. Do not let the lithium battery discharge more than its original design ** discharge C (do not let the lithium battery over discharge), this will cause damage to the battery, and let the battery's original ** battery capacity decrease. If you are on the lithium battery After charging, you can only charge one-half or three-quarters of the original battery capacity. You are most likely due to the battery damage caused by excessive current discharge when using a lithium battery. (The premise is that the battery capacity is not mislabeled).
4. It is important to monitor the voltage of individual lithium batteries in a battery pack to maintain the same voltage across the lithium batteries in the same battery pack, which increases the safety during use and extends battery life.
5. If you are making your own lithium battery pack, please remember to keep some space between each lithium battery to facilitate the heat dissipation of the battery. This is the most important when making more than two lithium battery packs.
6. Some lithium polymer batteries have aluminum and cathode contacts. If you want to solder them, you must remember that the general soldering procedure cannot be used on aluminum contacts. You may have to buy solder pads for soldering aluminum. Manufacturers who usually sell this battery will also sell soldering pads.