Wireless Charging Design Necessity: Understanding Lithium Battery Technology

COUNTS：133652019-09-17 10:14:24

The meaning of wireless charging is to charge batteries. If you don't know about batteries, don't talk about charging, let alone wireless charging. If you want to know about wireless charging, you should first know about batteries. Batteries here mainly refer to lithium batteries. Here is only the basic knowledge of batteries, suitable for all practitioners in the wireless charging industry.
Myth 1: Whether the battery needs to be activated, whether the new battery needs to be recharged three times, 12 hours each time.

Myth 2: Batteries are charged as little as possible and have a long service life.
Myth 3: Batteries will explode if they are charged for too long. If they are full, they need to unplug the power supply.
Myth 4: The faster the charge, the better the battery.
Myth 5: The larger the charging current of charger, the faster the charging.
Myth 6: Wireless charging is faster than wired charging.
Let's not discuss the reasons for these misunderstandings. Next, after analyzing the characteristics of lithium batteries, we can see the specific reasons.
Lithium batteries require at least the following protective measures for their special reasons:
1) Overcharge protection
When the battery is fast full, the general battery voltage is about 4.2V. It is necessary to cut off the charging path to prevent the battery from overcharging.
2) Over-discharge protection
When the battery is almost discharged, the general battery voltage reaches about 2.5V (different manufacturers will have some differences in voltage). It is also necessary to cut off the discharge path to prevent the battery from over-discharging.
3) Overtemperature protection
When the battery is charged or discharged due to excessive current or abnormal, the temperature of the battery will rise sharply. Generally, the temperature of the battery reaches about 60-65 degrees. The charging and discharging circuit must be cut off to ensure the safety of the system.
High temperature of batteries will also have a greater impact on the service life of batteries. If the batteries work in high temperature environment for a long time, such as more than 45 degrees, the service life of batteries will be severely shortened.
Many wireless charging receivers are close to batteries. Some manufacturers'receivers are unreasonable in design, inefficient and have serious fever. At the same time, they will seriously affect the life of batteries. Friends who do wireless charging must pay attention to this part.
In addition, some protection systems will also protect charging current and discharging current to prevent overcurrent or short circuit of the system.
Mobile phone batteries are equipped with protection system, if the battery is full, the battery protection system will automatically shut off, cut off the charging circuit, do not worry about the danger of battery explosion.
(3) Battery charging
The analysis of battery must be based on the analysis of battery charging and wireless charging. Because of its own characteristics, lithium battery charging is also required. If the battery is seriously over-discharged and the voltage is very low, it can only be charged with a small current to activate the battery slowly, otherwise it will cause great damage to the battery.
In addition, charging or discharging batteries with high current and high rate will do harm to batteries, which will affect the service life of batteries.
The charging process of batteries in the industry is generally divided into three stages: trickle current, constant current and constant voltage.
When the battery voltage is too low, trickle current is used to charge the battery. When the battery voltage reaches the normal voltage, constant current is used to charge the battery quickly. When the battery is full quickly, it is changed to low current and constant voltage to recharge the battery slowly.
For instance:
Often happens, many friends sometimes want to simply compare the charging speed of two wireless chargers. Generally, two mobile phones have less power (if 50%) or more power (if 90%) and charge them for 10 minutes at the same time to see the results. One is about 5%, the other is only about 1%. Ask me how the difference is. So big, I can only say that the contrast is too big.
What else is full, judging by battery voltage is not very accurate. There is a standard in the industry. It is generally believed that when charging at constant voltage, the charging current is about 0.1 times that of charging at constant current.