Power bank is a portable device that integrates power storage, boosting, and charging management. Lithium battery cells are generally used as storage media, because lithium battery cells are relatively small in size, large in capacity, widely circulated in the market and moderate in price, and are widely used in digital products.
The principle is the same as charging a mobile phone. Connect to a 5V USB computer interface or a USB charger to charge the power bank. Therefore, there must be a charging management system inside the mobile power supply. The charging management system can automatically adjust the charging current according to the voltage of the lithium battery. The process includes: pre-charging, constant voltage charging, and floating charging.
The mobile power supply is composed of three parts, the battery part, the circuit part (boost system and charge management system) and the shell part.
1. Mobile power cell: The cell is the core part of the mobile power supply, that is, the power storage of the mobile power supply, which is actually composed of batteries. Commonly used are ordinary lithium batteries, advanced lithium polymer batteries.
2. Boosting system: The mainstream technology of boosting basically adopts the boosting method of DC to DC. The domestic technology conversion efficiency is generally low, generally 50-70%. High-end in 75-80%. Relatively higher in the United States. There is also a step-down solution, which has relatively high efficiency, but has high requirements on the consistency of the cells, so it is rarely used.
3. Charging management system: At present, the domestic charging management system is relatively mature, and the intelligent IC monitors the entire charging process. Mainstream management ICs include PT4056, PX40 and so on. Charging time 5000maH is about 8 hours. Charging too fast has a bad effect on the life of the battery.
