How Do I Choose the Best Universal USB Charger?

Mobile phone chargers can be broadly divided into travel chargers, cradle chargers, and maintenance chargers. The main two types of contacts for general users. And the most sold on the market are travel chargers.

mobile phone charger

Mobile phone

Mobile phone charger aka:

Mobile phone chargers can be roughly divided into

1.Good quality charger can identify lithium battery and

We can also check the performance of the charger during use. The battery has a slight temperature rise during the later stages of charging

The charging method is the most critical. Charging a lithium battery requires a charger that specifically supports the lithium battery charging mode.

We know that the domestic civil rated voltage is 220V, and it is not possible to charge the mobile phone directly. The purpose of the mobile phone charger is to convert the high-voltage pulse of 220V into a low-voltage pulse of 5V, and then pass through a rectification and voltage stabilization circuit to 5V. stable

Speaking of this lithium-ion battery, let's briefly introduce it. The so-called lithium-ion battery is a battery that uses a carbon material that can store and desorb lithium ions as the negative electrode active material. The lithium ion symbol is Li-ion. Everyone knows that batteries are generally composed of basic elements such as the positive electrode, the negative electrode, the separator, and the electrolyte, so these materials used in lithium-ion batteries are generally the following:

Positive electrode: lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium manganate (LiMn2O4), etc .;

negative electrode:

When buying a compatible mobile phone charger, pay attention to the brand. It should be a product produced by a regular manufacturer. Because above

February 18, 2009

1. Discharge static electricity during cleaning. Clean the charger and charging interface regularly. When cleaning, use a damp cloth or an antistatic cloth. Never use a dry cloth (static charge)!

2. Water and moisture resistant. As an electronic product, accidental ingress of water or exposure to humid air when not used for a long time can cause different degrees of corrosion or oxidation to its internal electronic components.

3. Shock and shock resistant. The mobile phone charger is actually a fragile component, and the internal components cannot withstand being beaten. Especially to prevent accidental landing during use. Do not drop, hit or shake the charger. Rough handling of the charger can destroy the internal circuit board

4. Protect from cold and heat. Do not leave the charger in a place where the temperature is too high. High temperatures can shorten the life of electronic devices, damage the charger, and deform or melt some plastic parts. Do not store the charger in a cold place. When the charger works in a super-cooled environment, when the internal temperature rises, moisture can form inside the charger and damage the circuit board.

5. Resistant to harsh chemicals. Do not use harsh chemicals, cleaning agents, or strong detergents to clean the charger. To remove the stains on the appearance of the charger, you can scrub with a small amount of alcohol and cotton.

1. After connecting the battery and power supply to be charged, the power indicator and test indicator are on, while the charge and full indicator are off, there is no voltage output, and the battery cannot be charged.

Analysis and maintenance: This kind of failure is mostly caused by the charger switch oscillation circuit not working. In the actual maintenance process, it was found that the switch VT2 and the resistor R6 were most damaged. In general, the working voltage of the charging circuit of the battery E is low, and the probability of damage to its components is not very high, that is, the probability of damage to the circuit after the secondary of the switching transformer T1 is not very high.

2. After connecting the battery to be charged and the power supply, the status indicators show normal, but it is not charging or the charging time is long.

Analysis and maintenance: This kind of failure is mostly the damage of the triode VT3 (8550). After replacing it with a normal tube, the failure can be eliminated. If the transistor VT3 is normal, then use a meter to measure the voltage across the capacitor C3 (100F / 16V), which is normally about DC 8.5V. If the voltage is normal, you should check the resistor R7 or IC1. The normal parameters of each pin of IC1 are shown in the attached table. If the voltage is low, then measure the secondary output voltage of the switching transformer T1, which is normally around 5.5V AC. If the voltage is normal, the capacitor C3 or the rectifier diode VD3 is damaged. If the voltage is low, check the switching transformer T1 and its previous components.

Mobile phone chargers can be broadly divided into travel chargers, cradle chargers, and maintenance chargers. Generally, the first two types of users' touch are the first two. And the most sold on the market are tour chargers. There are also a variety of ways to tour chargers. Commonly, there are cheap duck-type mini travel chargers, usually desktop card-type chargers, and high-end desktop charging with LCD display. Device.

All mobile phone chargers are actually composed of a stable power supply (primarily a regulated power supply, a stable operating voltage and a satisfied current) plus necessary constant current, voltage limiting, and time-limiting control circuits. The output parameters marked on the original charger (referring to the line charger): for example, the output is 4.4V / 1A, the output is 5.9V / 400mA ... refers to the relevant parameters of the internal regulated power supply. Understand this principle, you will know that a (good quality) mobile phone charger is simply changed to an excellent quality regulated power supply! For example, 4.4V output can be used for 4.5V equipment, 5.9V can be used for 6V equipment use

Li-ion battery chargers commonly used in mobile phones use the constant-current voltage-limiting charging system. The charging current is usually about C2-that is, the two-hour charging rate is used. Constant voltage charging after 4.2V.

Lion battery is not suitable for the rapid charging method of DV / DT used by NIMH battery high-end fast charger, because Lion battery has strict restrictions on the charging current. Lithium ion (Li +) is very vivid, and high-current charging is very simple. risk.

When charging the phone for the first time, it is better to charge it for as long as possible-3 hours. Avoid overcharging. Too much will charge the battery above 100. Because the lithium battery is overcharged, it is dangerous. If you use a "rechargeable seat charger" and you buy a device "lithium battery with rough quality protection circuit board", then you are just waiting for the fire when charging! Do not expose the battery Under high temperature or severe cold, such as three volt days, the mobile phone should not be placed in the car and exposed to the scorching sun; or it should be placed in an air-conditioned room and placed in a place where the air is blowing directly.

When charging, it is normal for the battery to be a bit hot, but it should not cause it to have a "high fever". In order to avoid this situation, it is good to charge at room temperature (about 26 degrees), and do not lay anything on the machine. Stay away from any gold letter items. Mobile phone batteries should avoid contact with gold and silver jewelry, watches, metal accessories, pins, etc. just in case. Because when the socket of the mobile phone battery meets the conductor, a short circuit occurs, which causes the battery temperature to rise. The high temperature will volatilize the chemicals in the battery, generate very dangerous gases, and even explode in severe cases. Do not recharge the battery before it runs out. This will not only damage the battery, but also shorten its service life. You should develop a good habit of charging when the electricity is exhausted. ^[3]

Phone charger function

1. A good quality charger can identify lithium batteries and nickel-metal hydride batteries, and then determine the type of charging. On the maintenance circuit board of the lithium battery, there is an integrated circuit that stores the characteristic materials of the lithium battery. On the one hand, it allows the charger to identify the lithium battery, and determines the charging mode of "constant current" and "constant voltage". Identify the lithium battery to determine the discharge method.

2. The charging method of Ni-MH battery is "constant current". NiMH batteries are not afraid of overcharging. When NiMH batteries are overcharged, there will be a reverse reaction to prevent the voltage from rising excessively. This reaction will cause the battery to heat up slightly. In addition, nickel-metal hydride batteries are usually equipped with a thermistor to prevent the battery from being overcharged. At present, the operating voltage of most mobile phones is about 3.6V, so three Ni-MH battery cells are required. Generally, the nickel-metal hydride battery cell is overcharged to about 1.4 to 1.5V and is suspended. The maximum voltage of the three batteries is about 4.4V.

3. Because of the risk of lithium battery overcharging, the setting conditions for charge and discharge are more stringent than those of nickel-cadmium batteries and nickel-metal hydride batteries. A control circuit board is usually attached to the lithium battery to prevent overcharging. According to the characteristics of the lithium battery, the first paragraph of charging is based on the "constant current" method of charging, compared with fast charging and then using the "constant voltage" (between 4.1 to 4.2V) to make the battery reach the optimal state. There are some chargers on the market that cut corners and identify mobile phone batteries as nickel-metal hydride batteries. Charging with a "constant current" method often simply causes lithium batteries to overcharge. A good quality maintenance circuit board will now maintain the lithium battery to prevent the charger from continuously charging. If you encounter a circuit board with poor drawing, you will not only be unable to maintain the battery and overcharge the battery, but also deform, leak, explode, etc. the battery cell due to overcharging.

4. Most of the seat chargers use fast charging, which usually overflows within 3 to 4 hours. When the dock charger appears to be over, even if the battery is not removed from the dock charger, only a very small amount of power remains in the battery.

5. The memory effect of nickel-metal hydride batteries is not large, and they do not need to be discharged frequently, while lithium batteries do not need to be discharged at all. The chargers on the market have different quality discharge devices. Poor quality will have the appearance of over-discharge, and it is easy to form corrosion of the negative plate inside the battery (the electrolyte inside the nickel-hydrogen battery is an alkaline solution of potassium hydroxide), thereby reducing the battery life and normal usable capacity. In this situation, the battery will deteriorate faster if it is discharged and recharged each time. Under normal conditions, as long as the battery is used to actively shut down and then recharge, it is the best way to discharge the battery.

How to charge mobile phone charger

The need for lithium battery charging specifically supports the charger in the form of lithium battery charging, which is usually marked on the packaging of the charger. Many chargers are compatible with two types of charging. When purchasing, pay attention to the fact that it is still manually set by the switch. If it is manually set, it must be set correctly according to the type of battery being charged. Regarding nickel-cadmium / nickel-metal hydride batteries, the excellent charger uses a charging method with a negative pulse charge, which can reduce the polarization effect during the charging process. And usually cheap chargers use constant current charging. The battery charging waveform depends on the oscilloscope for accurate investigation.