Players set up a 18650 lithium battery box

Mobile power is the most popular product in the near future, and people are paying more and more attention to how to buy mobile power. In addition to traditional mobile power sources, players in other groups will choose to move power boxes, or battery boxes, with reliable 18650 batteries to create their own mobile power sources with exclusive capacity and price. So should buy mobile power or battery box is better? We 'll see.

18650 battery Use and Design

Whether it is a mobile power supply or a mobile power box, most of the contained batteries are so-called 18650 batteries. The 18650 battery name is so "special" that its model is based on its appearance and its diameter is 18mm long and 65mm, so it is called a 18650 battery. The appearance is similar to that of the No. 3 battery, but the volume and design are different from those of the No. 3 battery. 18650 is a type of lithium-ion batteries that can be repeatedly charged and discharged and is commonly used in mobile power supplies, flashlights, and some pen-electric batteries.

The voltage of 18650 is higher than that of the general battery No. 3, the battery voltage of No. 3 is 1.5 V, and the NiMH nickel-metal hydride battery is mostly 1.2 V. The rated voltage of 18650 is 3.7 V, and the saturated voltage full of electricity is different depending on the electrode material. Graphite is 4.2 V and Coke is 4.1 V, which is generally around this value. The termination discharge voltage is about 3V. If the termination discharge voltage is exceeded, it is called overdischarge and there will be damage to the battery.

Lithium-ion polymer battery

Lithium-polymer batteries (or lithium-polymer batteries), which are similar in name to lithium-ion batteries, are liquid organic solvents that replace lithium-ion batteries with colloidal or solid polymers. For example, mobile phone batteries and lightweight pen batteries are mostly lithium polymer batteries, and a few mobile power sources are also used. The feature is that the shape is not limited by the hard shell of a lithium ion battery, which can be made into a flat or special shape, and the weight of the hard shell is also relatively light.

1, 18650 lithium ion batteries are often used for mobile power supplies. Their models are derived from diameter and height. Initially, industrial products were later increased due to the increase in peripheral products, and the visibility of the retail market increased.

2.Lithium polymer batteries are small in size and light in weight, and a few mobile power supplies will be used.

3, even if the battery is framed in Square, the interior may be connected in parallel with 1,8650.

4, 18650 is very different from the size of the general No. 3 battery, and the weight of four parallel mobile power supplies is not light.

The models of 5, 18650 are derived from the diameter and height. They are much larger than the No. 3 battery and the voltage is not the same.

Elements of a battery

Now that we're talking about batteries, explain how they work. The main composition of the battery is a positive electrode material, a negative electrode material, an electrolyte, and an isolation membrane. At most, a shell is added. The principle of charging and discharging of the 18650 is similar to that of a general battery. The difference lies only in the structure of the material and detail. It is believed that the basic structure of the battery should be even Primary school students know. So what's so special about the 18650 material? The common cathode materials of lithium-ion batteries are: common lithium cobalt acid(LiCoO2), lithium manganese acid(LiMn2O4), triplet(LiCoxNiyMnzO2), lithium iron phosphate(LiFePO4), and many manufacturers. The initial 18650 battery material used was lithium cobalt acid. In the near future, it has been replaced with ternary materials.

The negative electrode is made of carbon and can be divided into graphite and non-graphite systems (such as coking carbon systems). The graphite negative electrode materials have a stable voltage effect and are used in electronic materials and batteries with obvious advantages. The energy density of graphite is higher, the structure of the material itself is more regular, and the irreversible capacitance is relatively low. The role of electrolytes should be known to be the conduction of lithium ions and the avoidance of positive and negative polar contact. Commonly used materials are lithium salts and aprotic solvents. Electrolytes can be divided into three categories, liquid electrolytes, polymer electrolytes, and solid electrolytes. Most lithium batteries on the market are liquid electrolytes, but because liquid electrolytes are relatively easy to leak, they may also explode and have relatively low safety. Solid electrolytes have better safety, but poor conductivity is still not commercialized.

As for the isolation membrane, it is a blunt element in the battery and does not participate in the chemical reaction of the battery. Its role is to isolate the positive and negative poles of the battery and avoid direct contact to create a segment. The second is to let the ion current pass and the less the resistance, the better. There are many kinds of materials for the isolation membrane, and PP and PE are common materials. The isolation film using PP and PE materials has a congenital safety mechanism. When the internal temperature of the battery is too high and it is close to the melting point of PP or PE materials, the crystalline structure of PP and PE will disintegrate, causing most of the holes to be blocked, making the resistance greatly increased., Isolated electrodes continue to react to protect the battery.

Note: The following disassembly is dangerous, do not imitate

1, 18650 battery is similar to the general battery structure, the biggest difference is the material.

2, the lower right of the battery is the safety valve, is the most important safety mechanism of 18650. When the internal temperature is too high or the pressure is too large, the internal gas will be eliminated through the relief valve to avoid high pressure causing an explosion.

3, the battery is made of sheet material curled, mostly copper foil aluminum foil and coated with positive and negative materials.

4, after leveling out like a piece of paper, the dismantling will also have an electrolyte outflow.

2 Benefits of self-assembly of mobile power

The general mobile power supply consists of a battery plus a mobile power box. You can not choose or even see the type of battery used in it. Some manufacturers on the market refer to the sale of mobile power boxes. Mobile power boxes say that they are power control circuit boards and chips, plus products composed of battery cells. So what are the benefits of self-organizing mobile power? It can be roughly divided into the following points.

1. Choose your own battery and circuit chip

The most unbearable thing about mobile power sets is the inability to confirm the type of battery and circuit design used. Even if you see other people's mobile power disassembly charts, the battery origin and model of each batch may also be different. Furthermore, suppose you are sure that the battery is fine, but you still can not confirm whether the circuit is well designed, whether the protection mechanism is sufficient, and lack of transparency is the most criticized feature of the mobile power supply of the suit.

The advantage of mobile power boxes is that they can choose their own large-scale or word-of-mouth 18650 batteries, such as Japanese brands such as Sanyo and Panasonic, and can be used with battery boxes suitable for size and circuit design. The autonomy is relatively high. This is the same as DIY computers. A set of computers can help you install it well, but it does not guarantee that all components are suitable for you. DIY, although it is troublesome, at least all components can be selected.

In addition to installing the 18650 mobile power box, there is also a version of the No. 3 battery, but the battery capacity is relatively low.

2. Cheap price, battery capacity depends on

The price is the advantage of DIY. Excluding a few inferior products such as millet or completely insufficient power capacity, the cheapest price of mobile power boxes is only about 300 yuan, 18650 batteries are priced at about 100 yuan, and high prices such as the larger battery capacity Panasonic NC18650B is about 170 yuan. (Note: The price of Panasonic batteries has recently soared. It is recommended to find other alternative products.) The entire group of 41,8650 mobile power boxes can be fixed if it is cheap. (The price here is Taiwan dollars)

In addition to the price advantage, the capacitance advantage is also the missing part of the suit's mobile power supply. In general, the most common combination of mobile power sets is 4 18650, with a total battery capacity of about 12,000 mAh, and most batteries are non-replaceable. Since most battery boxes are designed in parallel, if you can install up to 4 battery boxes, you can install 1 to 4 batteries on demand.

One of the disadvantages of the mobile power supply of the suit is that it can not adjust the battery capacity. The desired brand does not necessarily have the required battery capacity version.

The page contains the contents of the machine translation.