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Mobile Power Working Principle and Mobile Power Composition
- Apr 03, 2018 -

With the rapid development of the global economy and the continuous improvement of people’s living standards, there are more and more portable electronic products, such as laptops, tablet computers, mobile phones, digital cameras, camcorders, portable DVDs, PDAs, MP3s, and MP4s. GPS, warm equipment, health care equipment, etc. However, the original battery of these devices will not meet the normal operating time of the device because of the low battery capacity. Mobile power came into being. The mobile power supply can solve the problem of power supply for many mobile devices, thus completely solving the problem of power shortage. Some products on the market have high capacity, stand-alone capacity up to 8000mAh, intelligent power indication, Japanese peak power management technology, and polymer lithium-ion batteries, which are widely used in 5v equipment.

The safety of mobile power is also an issue that people continue to pay attention to. However, in the chaotic situation of the market, the unsafe factors of mobile power are also increasing. Mobile power must have: short circuit, overcharge, over discharge, constant current, constant voltage and other protection measures, but also should have high-performance power management technology. Only in this way can we be assured of buying and using our peace of mind.

Mobile power is a portable device that integrates storage, boost, and charge management. Lithium batteries are generally used for the dielectric medium. Lithium batteries are widely used in digital products due to their compact size, large capacity, wide market circulation, and reasonable price. The voltage of lithium is between 2.7-4.2V, and the voltage drops with the decrease of power. The voltage of 2.7-4.2V cannot be directly charged to other digital products because the lithium voltage of digital products is also 2.7-4.2V, and the voltage of the same potential cannot be charged. Therefore, the external power output from the mobile power supply must have a boost system. The 2.7-4.2V lithium voltage is boosted to 5V, so that other digital products can be charged, such as mobile phones, MP4s, tablet computers, and PSPs.

 

Of course, mobile power is not a one-time device, and it can be used hundreds of times more than once. So when the power of mobile power is used up, we must charge the mobile power. The principle is the same as charging a mobile phone. Connect to a 5V USB computer interface or USB charger to charge the mobile power. Therefore, there must be a charge management system inside the mobile power supply. The charging management system can automatically adjust the charging current based on the voltage of the lithium battery. The process includes: pre-charging, constant voltage charging, and float charging.

The mobile power source consists of three parts, the cell part, the circuit part (boost system and charge management system) and the housing part. Each of the components is described below.

Mobile power batteries:

The battery core is the core part of the mobile power supply, which is the power storage of the mobile power supply. It is actually composed of batteries. Commonly used polymer lithium, 18650 lithium, AAA nickel-hydrogen batteries.

1. Polymer lithium battery: standard voltage 3.7 V, shape, customizable, large capacity, inexpensive, widely used, such as: mobile phone, MP4, portable speaker. The polymer lithium battery is a kind of lithium-ion battery that adopts aluminum-plastic flexible packaging in the structure. It is safer than the battery core of the battery, and it will not cause high-risk security risks when working. Its high power density, smaller thickness, lighter weight, and large capacity, many cell phone batteries are made of polymer batteries. Its internal resistance is small, even lower than 35mΩ, which greatly reduces the self-consumption of the battery and makes the power utilization rate higher. In addition, its shape can be customized, according to the appearance of the shell is tailor-made, many appearance of small mobile power is the use of flexible packaging batteries.

2. 18650 lithium battery: standard voltage 3.7V, with small size, large capacity, mainly used in notebook computers and other high-end products. The 18650 is a steel-aluminum shell cell, and its technical aspects are relatively mature. The 18650 cell is a cylindrical cell with a diameter of 18mm and a height of 65mm, and its capacity is usually between 2000-3000mAh. The 18650 batteries used in most of the mobile power supplies on the market are lithium-cobalt-acid batteries. The single-cell nominal voltage is 3.7V and the charging voltage is 4.2V. Compared with the previous nickel-metal hydride and nickel-cadmium batteries, this type of battery has a larger capacity and a longer life, and the number of charge and discharge cycles can reach more than 500 times, and the safety factor is higher, non-toxic and environmentally friendly.

3. AAA NiMH battery: standard voltage 1.2V. The capacity is relatively small. Should be extensive, home appliances, players and so on.

Boost system:

The boost mainstream technology basically adopts the DC to DC boost method. Domestic technology conversion efficiency is generally low, generally 50-70%. Taiwan's 75-80%. The United States will be relatively high. There are also buck solutions, and the efficiency is relatively high, but the consistency of the batteries is so high that they are rarely used.

Calculate the power output power according to the product conversion efficiency:

Take 5000mAh mobile power as an example: actual output capacity = (mobile power capacity 5000mAhx3.7Vx conversion rate 85%)/5V=3145mAh

Charging management system:

At present, the domestic charging management system is relatively mature, and the smart IC monitors the entire charging process. Mainstream management ICs include PT4056 and PX40. Charging time 5000maH about 8 hours. Overcharging has an adverse effect on the life of the battery.

Shell:

1. Plastic shell: General mobile power is based on ABS/PC material.

2. Metal shell: aviation aluminum shell and so on.