In order to make you use the polymer lithium battery more safely, please read the following text carefully.

Combustion: Charging with a non-lithium battery charger may cause damage, smoke, heat or burning of the lithium battery!​
Damage: Over-discharge, over-charge or reverse charging will immediately cause damage to the lithium battery!
Charging: the charging current should not be greater than 1/2 of the battery capacity; the charging cut-off voltage is 4.20V±0.05V for a single battery; the charger can fully charge the corresponding lithium battery pack, and there is an indicator light to indicate the charging process (for details, please refer to the charger manual).
Discharge: For the first use, please use the recommended charger to charge;
When using it continuously, please pay attention to check the battery voltage. The total voltage of the 3-series battery pack shall not be lower than 8.25V; the total voltage of the 2-series battery pack shall not be lower than 5.5V; the voltage of a single battery shall not be lower than 2.75V. Voltages below these ratings will cause the battery to gass up and be damaged!
Storage: The self-discharge rate of lithium batteries is higher than that of nickel-metal hydride batteries. Long-term storage is prone to over-discharge. Please check the voltage regularly to keep the single voltage between 3.6V and 3.9V;
Storage conditions: temperature -20℃～+35℃; relative humidity 45%～85%.
The polymer lithium battery is packed with aluminum-plastic film, and it is forbidden to scratch, collide or pierce the surface of the battery with sharp objects. The battery tabs are not very strong and can be easily broken when bent, especially the positive tabs.
Each cell has flux tabs cold soldered on the positive lug to help you solder. When soldering, a constant temperature soldering iron of <100W should be used to tin the tabs, the temperature should be controlled below 350℃, the soldering iron tip should not stay on the tabs for more than 3 seconds, and the number of soldering should not exceed 3 consecutive times. The welding position is more than 1cm away from the root of the tab. The second welding must be done after the tabs have cooled.
The polymer lithium battery pack has been well welded, and it is forbidden to disassemble or re-solder. In theory, there is no flowing electrolyte in the lithium polymer battery, but if the electrolyte leaks and comes into contact with the skin, eyes or other parts of the body, immediately rinse with clean water and seek medical attention.
Do not use damaged battery cells (damaged sealing edge, damaged casing, smell of electrolyte, leakage of electrolyte, etc.). If the battery heats up rapidly, please keep away from the battery to avoid unnecessary damage.

With the advancement of lithium technology, it is possible that lithium batteries may one day replace conventional submarines’ diesel engines. The Japanese Navy has already implemented the use of LIBs in its Soryu-class attack subs. South Korea is also testing the technology for their next-generation attack subs. Other applications for LIBs include the US Special Forces delivery vehicle, as well as the Russian Surrogat unmanned mini-sub.

However, the technology has its drawbacks. Lithium is flammable and can catch fire when exposed to water. Leaks in lithium can reach temperatures of 3,600 degrees Fahrenheit. Furthermore, a fire in a lithium battery releases hydrogen gas, which is highly flammable. While the benefits of using lithium batteries for submarines are numerous, there are still significant concerns about the safety of this technology.

While there are a number of downsides to lithium-ion batteries, the technology has proven to be reliable. Japan, for example, plans to build one more Soryu-class submarine with LIBs. The development of a LIB-submarine would also allow Japan to upgrade its older Stirling AIP powered Soryus. So, while LIBs present certain risks, they are expected to make an impact in the future of submarine propulsion.

While LIBs have some risks, these batteries have been proven to be safer than lead-acid batteries. The research and development of light-metal batteries will benefit from this data. The US Navy has already chosen lithium-ion main batteries for its KSS-III batch 2 submarines. In addition, South Korea has chosen to use lithium-ion batteries in its nuclear-powered Soryu-class boats. The seventh Soryu-class boat is also expected to incorporate a combination of Stirling Engines and lithium-ion batteries. These vessels will serve as a bridge between lead-acid and lithium-ion technologies.

The development of LIB batteries is a challenge for the lead-acid-powered submarines. They can’t be fully replaced by lead-acid batteries and will remain a major asset for the military for years to come. But the advancements in the technology have opened up new doors for submarines. The resulting improved performance means they can cruise for longer periods of time under the water.

Despite the risks of Lithium-ion batteries, they are the most reliable option for submarines. Although the lithium-ion batteries are safer than lead-acid batteries, they do have some drawbacks. In addition to high cost, they have high maintenance and are not completely safe to use in the ocean. Moreover, they are expensive to operate, requiring extensive maintenance.

The benefits of LIBs are considerable. In addition to their high-speed capability, they are also incredibly safe and durable. If the marine environment is a threat to the life of a submarine, it is essential to ensure that it is safe to use and a reliable and long-lasting power supply. Ultimately, LIBs will save lives. But for now, these batteries are not without risks.

Because of the huge benefits of lithium-ion batteries for underwater vehicles, they have many other advantages. Compared to conventional submarines, they have a lower cost than lead-acid submarines. They can also be operated for longer periods of time. This makes lithium-ion-powered subs an attractive option for many companies and governments. This technology can be used in other fields as well, including for commercial purposes.

The use of lithium batteries for conventional submarines could dramatically reduce their costs. The cost of lithium-ion batteries could be cheaper than traditional lead-acid batteries, and the technology may be more efficient than lead-acid. Additionally, the high-energy density of lithium-ion-based batteries will provide longer service life. They are also more reliable than lead-acid batteries.

The development of lithium-ion batteries for submarines is an exciting development. The advanced batteries will give the submarines better endurance under water, which is crucial for a modern submarine. These batteries may also be the main power supply for conventional submarines. They are not only cheaper than lead-acid batteries, but they are lighter, more efficient and more environmentally friendly. In the future, these submarines may use this technology to be able to operate at greater depths than ever before.

How to detect the charging loss of an 18650 lithium battery pack?
1. Battery consumption performance: battery voltage does not go up and capacity decreases. Measure directly with a voltmeter, if the voltage across the 18650 battery is lower than 2.7V or there is no voltage. Indicates that the battery or battery pack is damaged. The normal voltage is 3.0V ~ 4.2V (generally the 3.0V battery will cut off the voltage, the 4.2V battery voltage will be fully charged, and some have 4.35V).
2. If the battery voltage is lower than 2.7V, you can use the charger (4.2V) to charge the battery. After ten minutes, if the battery voltage has rebounded, you can continue to charge until the charger indicates that it is fully charged, and then check the full voltage.
If the fully charged voltage is 4.2V, it means that the battery is normal. It should be that the power consumption was too much in the last use, and the battery is cut off. If the fully charged voltage is much lower than 4.2V, it means the battery is damaged. If the battery has been used for a long time, it can be judged that the battery life has expired and the capacity is basically exhausted. should be replaced. Basically there is no way to fix it. After all, lithium batteries have a lifespan, not infinite.
3. If the 18650 lithium battery pack is measured and the battery has no voltage, there are two situations at this time. One is that the battery was originally good, and it was caused by long-term power loss storage. This kind of battery has a certain probability of recovery. Generally, it is activated by a lithium battery pulse. It is possible to recharge the battery several times in a short period of time by using an instrument (lithium battery charging and discharging instrument). Generally, the repair cost is not low, and it is better to buy a new one. Another possibility is that the battery is completely worn out, the battery separator is broken down, and the positive and negative electrodes are short-circuited. There is no way to fix this kind of thing, just buy a new one.
18650 lithium battery pack battery repair method principle:
1. The metal surface of the 18650 lithium battery pack that has been used for a long time will be oxidized to a certain extent, which will lead to poor contact between the mobile phone battery and the mobile phone, and the use time of the lithium battery will be shortened. Rusty substances that make the battery better in contact with the phone.
2. The low temperature can change the electrolyte inside the lithium battery pack and promote the chemical reaction of the battery that has just been frozen. The use of lithium batteries is actually a charging and discharging process. During this time, the negative and positive charges in the battery collide with each other. When the lithium battery is placed in a low temperature environment, the microstructure of the lithium film on the surface of the lithium battery and the electrolyte, as well as their interface will change significantly, resulting in a temporary inactivity inside the battery and a reduction in leakage current. So after charging again, the standby time of the phone will increase.
The cycle life of the lithium battery pack is about 600 times. If there are too many charging times, the thermal motion of the molecules will gradually destroy the microstructure of the internal molecular arrangement, and the efficiency of storing electric charges will gradually decrease.

Nowadays, many rechargeable electrical appliances in life use lithium batteries, such as soft packs, cylindrical, rectangular and so on. Among them, cylindrical lithium batteries are divided into various models according to their size, such as the most common 18650, 22650, 32650 and so on. The number 18 in the model like 18650 indicates the diameter of the battery, 65 indicates the length of the battery, and 0 indicates that the battery is a cylinder.

The voltage of a single-cell lithium battery is generally 3.2V to 3.7v, and the voltage used by many electronic devices is 12V, so we need to use multiple lithium batteries to form a group to achieve 12v, and the lithium battery assembly also needs to be equipped with a protective plate.

The main purpose of the protection board is to play overload protection, short circuit protection, overheat protection, low voltage protection, overvoltage protection, battery balance, overcharge protection, etc., mainly to protect the battery from being damaged.

Since the capacity of a single battery is relatively small, 12 32650 lithium batteries are prepared, four are connected in series to form a group of 12V, and then three groups of 12V are connected in parallel to increase the capacity and voltage.

Assembling the battery requires the use of nickel tape, high temperature tape, and battery brackets.

Generally, the connection of lithium batteries is to use spot welding to bring the nickel to the point. If there is no spot welding machine, you can use sandpaper to polish both ends of the battery, and then you can use an electric soldering iron to weld.

Get the battery line, measure the voltage, and see if the capacity is the same. Don’t put the different ones together.

Then install the battery and battery holder and arrange them in a positive and negative order.

Then wrap the heat resistant tape around it.

Connect the batteries with nickel tape, a soldering iron will do without a spot welder. By the way, stick the protective plate on top of the tape.

For the effect of spot welding of nickel strips, it is necessary to distinguish which one is connected with which one, otherwise it will cause a short circuit.

Then solder the protection board and the plug. Generally, the protection board will indicate the connection method in detail, and it is enough to connect with wires.

If you feel that one plug is too few, you can add another one, and the 12V lithium battery is completed.