How to select the charger for electric vehicles?

1 introduction of electric car charger
Electric car charger is a charging device specially designed for electric bicycle battery. When the charger is damaged, the electric car will be "difficult" and then "hard step". Electric chargers can be divided into two types:
Negative pulse charger
Lead acid battery has a history of more than 100 years, and it has started the universal view and operation rules of the world: charging and discharging rate is 0.1C, and life expectancy is longer. American Max announced to the world in 1967 that the pulse current was charged at a rate greater than 1C, discharging the battery intermittently during charging. Discharge is beneficial to eliminate polarization, reduce electrolyte temperature and increase the ability of plate to accept charge.
In 1969, some Chinese scientists and technicians made many kinds of brand fast charger according to Mr. Max's three law. The charging cycle process is: large current pulse charging, cutting off charging channel, transient discharge to battery, stop discharge, connection charging channel and large current pulse charge...
Before and after 2000, this principle was used in the charger of electric vehicle. During the charging process, the charging path was not cut off, and the battery was short circuited by a small resistance. In case of short circuit, the inductor is connected in the charging path without cutting off the charging path. A short circuit of 3-5 milliseconds (1 seconds = 1000 milliseconds) in one second can protect the power conversion part of the charger because the current in the inductor can not be hopping and short circuited. If the direction of charging current is positive, the discharge is naturally negative. This is the so-called "negative pulse charger".
Three stage charger
In recent years, the three stage charger is widely used in electric vehicles. The first stage is the constant current stage, the second stage is called the constant pressure stage, and the third stage is the trickle flow stage. From the angle of electronic technology for battery: the first stage is called the charge limiting stage, the second stage is called the Gao Hengya stage, the third stage is called low constant pressure stage more appropriate. When the second stage and the third stage are converted, the panel indicator changes accordingly, and the first, second stage of most chargers is the red light, and the third stage changes the green light. The conversion between the second and the third phases is determined by the charging current, which is greater than a current entering the first second stage, less than a current entering the third stage. This current is called alternating current, also called transition current. [detail >]
2 working principle of electric vehicle charger
As shown in the electric charger circuit diagram above. 220V alternating current is suppressed by T0 bidirectional filtering, D1 rectifier is pulsating DC, and C11 is filtered to form a stable DC current of about 300V. U1 is a TL3842 pulse width modulation integrated circuit. The 5 feet are power negative, the 7 foot is the power cathode, the 6 foot is the pulse output directly driving the field effect tube Q1 (K1358) 3 foot as the maximum current limit, and the adjustment of the R25 (2.5 Ohm) resistance can adjust the maximum current of the charger. The 2 foot is voltage feedback, which can adjust the output voltage of the charger. The 4 feet are connected to the oscillating resistance R1 and the oscillating capacitance C1.
T1 is a high frequency pulse transformer with three functions. The first is to press the high voltage pulse to a low voltage pulse. The second is to isolate high voltage, so as to avoid electric shock. Third is the power supply for the UC3842. D4 for high frequency rectifier (16A60V) C10 for low voltage filter capacitance, D5 as a 12V voltage regulator, U3 (TL431) as a precision reference voltage source, with U2 (optocoupler 4N35) to automatically adjust the function of the charger voltage. Adjusting the W2 (trimming resistor) can fine tune the voltage of the charger. D10 is a power indicator. D6 is a charging indicator. The R27 is a current sampling resistor (0.1 ohms, 5W) that changes the resistance of W1 to adjust the inflexion current (200-300 mA) of the charger to the floating charge.
At the start of the electricity, there is a voltage of about 300V on C11. This voltage is loaded to Q1 by T1. The second way through R5, C8, C3, reached the seventh feet of U1. Force U1 to start. The 6 legs of the U1 output square wave pulses, Q1 works, and the current flows through R25 to the ground. At the same time, the secondary coil of T1 generates inductive voltage and provides reliable power to U1 through D3 and R12. The voltage of the T1 output coil is stabilized by D4 and C10 rectifier, and a stable voltage is obtained. This voltage is charged to the battery through D7 (D7 prevents battery current from being poured back to the charger). The second route is R14, D5, C9, which provides 12V power for LM358 (dual operational amplifier, 1 pin power supply, 8 pin power supply) and its peripheral circuit. D9 provides the reference voltage for LM358, and the R26 and R4 divider reaches second feet and fifth feet of LM358. When normally charged, the upper end of the R27 has a voltage of about 0.15 0.18V. This voltage is added to the third leg of LM358 through R17, and a high voltage is sent from the 1 pin.
This voltage is driven by R18, forcing Q2 to pass, D6 (red light) light, second way into the 6 feet of LM358, 7 feet output low voltage, Q3 turn off, D10 (green light) extinguished, charger into the constant current charging stage. When the battery voltage rises to about 44.2V, the charger enters the constant voltage charging stage, the output voltage is maintained at about 44.2V. The charger enters the constant pressure charging stage, and the current gradually decreases. When the charging current is reduced to 200mA - 300mA, the voltage at the upper end of the R27 decreases, the 3 leg voltage of LM358 is below 2 feet, the 1 pin outputs low voltage, Q2 turns off, and D6 goes out. At the same time, 7 feet output high voltage, this voltage leads Q3 to turn on all the way, D10 lights up. The other way is D8, W1 to the feedback circuit, so that the voltage is reduced. The charger enters a trickle charging stage. After 1-2 hours, the charge is over. [detail >]
3 car charger selection and purchase skills
Determine the battery voltage or output voltage
That is to say, the V of the electric vehicle battery or the output voltage of the original charger. There are two ways, one is to look at the original charger to determine the voltage: general.

The general battery voltage is 48V, corresponding to the original charger output voltage is about 59V; 60V battery, the corresponding original output voltage is 73.5V. The second way is to look at the battery voltage: there are several batteries in the general battery pack. The model is 6 - DZM - 12/20, indicating that each battery is 12V. So, there are several batteries in the electric car, and the 4 battery is 48V. For 8 - DZM - 12/20 batteries, each battery is 16V, and the 4 battery is 64V.
Determine the capacity of the battery or the output current
Determine the battery capacity of AH or the output current of the original charger. A look at the original charger to determine the capacity: the original charger output current is 1.8A indicating that the battery is 12AH. Second to see the battery judgment voltage: the battery box in the general battery has a write model, such as 6 - DZM - 12, 12 is the 12AH battery, 6 - DZM - 20, 20 is the 20AH battery. The three is based on the mileage of charging run: in general, the battery in 1 years is full of 25-40 kilometers running, and the charger of 12AH is more suitable. Running 45-60 kilometers, 20AH is more suitable.
Determining the positive and negative pole of the charger
It is suitable for electric vehicle charger interface shape. The more common interfaces in the market are T type prefix, three vertical prefix, middle horizontal prefix, round head, and some pin plugs may be very different. The charger can be used to charge the battery charging interface to find the positive and negative pole. The purchase of the charger output is consistent with the charging socket, and the negative electrode of the charger will damage the charger and the battery.
Judge the quality of the charger
A good electric vehicle charger adopts positive and negative pulse technology, which can effectively prevent, suppress and eliminate the sulfuration and polarization of the battery. The capacity of the new battery can be kept stable for a long time, and the capacity of the old battery that has been polarized and capacity is reduced will effectively prolong the battery life 2~3 times. It has the functions of intelligent timing protection, automatic temperature compensation, instant impact protection of electric network, super moisture-proof, anti-corrosion and so on.
Selection of brands
Generally speaking, there are 4 reasons for battery damage: loss of water, vulcanization, imbalance, thermal runaway (charging). We must choose products with great brand name and good reputation, and many inferior chargers in the market are very easy to produce overcharge, under charge, water loss, vulcanization and so on. It is a great hidden danger to the safety of the consumer's personal and property. Large brand charger products have designed a lot of charging protection functions, greatly increasing the safety and efficiency of charging. [detail >]
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4 how to use electric car charger
How long is the battery car charging?
The correct charging time is green light, then float 1 to 2 hours, then cut off the power supply. Electric car charger has no overcharge protection function, although the green light is bright, but because can not cut off the power supply, in fact, the battery is still continuing to charge, continue to decompose and evaporate the water in the battery. [detail >]
What's the harm of overcharging time?
Two principles should be grasped in electric vehicle charging: first, it should be relaxed. Two is not to overcharge. Excessive charging time will consume the water in the battery too much, accelerate the process of the plate's vulcanization, and make the battery drop gradually because of water shortage until the battery is filled and scrapped.
Is electric car charger general?
Electric chargers can not be used in theory, the main purpose is to see whether the voltage and current are consistent. Many users feel that if they can be able to plug in the lamp, it can be used. In fact, it is very easy to fill the battery. [detail >]
5 electric vehicle charger fault maintenance
1, the power does not start: plug in the power supply, the large capacitor has 300V voltage, unplug the power, measure the 2 terminal of the large capacitor again, or the 300V voltage does not drop. After the capacitor is discharged, the starting resistor can be replaced. The starting resistor is 150K in the power input section and 2W in power.
2, starting difficulties: sometimes can start sometimes can not start, repair welding line board, post test machine, if still please input a part of the small capacitance to replace the new test machine, 50V47UF.
3, electric vehicle charger has been green light: there are four cases. The charger's converter is damaged, can not convert and charge, replace the charger resistance; battery open welding, use multimeter check; charger insurance burning, replacement charger; power line and battery socket off, contact bad, check and replace.
4, electric vehicle charger has been red light: This is the reason for battery polarization and battery loss. Timely maintenance and treatment can be recovered. The method is; the battery adds 15ML pure water, charge with 4 an electric current, charge the current to 1 an, stop for 2 hours, measure the voltage of each battery to 13.3, if one can not recharge the battery until it is reached. And then string the battery up, and it's all right.
5, high output voltage: electricity, voltage higher than more than 70 V, charging no turn light, first to weld the circuit board again, try again, if the voltage is high, please replace the optocoupler, re test machine, or high output, replace 431 reference voltage regulator, try again.
6, high calorific value and abnormal noise: the cause of the failure is caused by damage of R31 and C17 of output stage. In addition, C12 open circuit or false welding will cause the above fault.
7. The output voltage is unstable: first,