Use a solar panel to charge a 3.7V/6600mAh lithium battery. The charging current is generally 1-2A. Generally, the higher the charging current, the faster the charging speed, but the power of the solar panel should also be larger. Since the end-of-charge voltage of lithium batteries is generally 4.2V, it is best to use a 5V battery panel to charge a 3.7V lithium battery using a solar panel. In this way, you only need to add a TP4056 lithium battery charging module. charging, and usually no additional voltage is required.
▲Single cell lithium battery charging module.
The TP4056 charging module shown in the image above is suitable for charging a single lithium battery. Its input voltage range is 4-8V, charging end voltage is 4.2V, charging current is adjustable, le maximum. is 1A, and there is a charging indicator light and a full indicator light. The red LED indicator lights up when charging, and the green LED indicator lights up when fully charged.
The wiring method of the charging module is as shown in the figure above. Its In+ and In- terminals are connected to the positive and negative poles of the 5V solar panel respectively, and the BAT+ and BAT- terminals of the module are connected to the positive and negative poles of the 3.7V lithium battery respectively. Since the charging IC is equipped with an anti-reflux circuit, no external isolation diode is required.
▲5V/2W solar panel.
The maximum input voltage of the above charging module is 8V, so a 5V solar panel can be used for charging, which can omit the voltage conversion circuit. Due to the large charging current, it is recommended to use 4-5 2W solar panels in parallel.
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Schematic diagram of 18650 single cell battery charge and discharge protection circuit
What circuit is it? If there is no picture, how can I see it? Can you understand the principle of the circuit? Single-cell protection card
1. Overload protection point and overload protection recovery point voltage
When the battery charging voltage reaches the set value VC, 4.125-4.300V (the specific overload protection point voltage depends on the chip manufacturer) Setting, the manufacturer can choose the IC chip according to the specific parameters and requirements of the battery cell), as shown in the figure above: When VD1, the pin Cout becomes low level, MOS tube T1 is cut off and charging stops; when thebattery core voltage drops to VCR3 0.6-4.2V (the specific recovery voltage of overload protection depends on the integrated circuit and the battery cell parameter design is integrated during the design ), Cout outputs are high. level, the MOS tube T1 is turned on and charging continues, the VCR must be smaller than VC by a fixed value to avoid frequent jumps.
2. Working principle of over-discharge protection and over-discharge protection recovery
During the battery discharge process, when the cell voltage is discharged and drops to the value set VD (2.1 -2.45V, overdischarge protection point voltage generally cannot be designed and can only be set by different chip manufacturers). When the output voltage VD2 is low, after a short delay, Dout becomes low,T2 is cut off and the discharge stops when the battery is put on charge. When the internal OR gate is reversed and T2 is reactivated to prepare for the next discharge.
3. Overcurrent and short circuit protection
When the battery discharges, when the charging circuit current exceeds the set value or is short circuited, the voltage applied to the MOS tube T2 will increase, the level of the sense resistor R3 will produce a voltage drop after reaching the potential value set by the integrated circuit, cout2 will become a low level, the MOS tube T2 will be turned off, and the power will be cut off. The overcurrent value can be obtained by changing R3 to obtain the desired overcurrent value.
The above is the basic principle of battery protection board management for a single battery. It is very simple since the voltage of the protection point of different materials is different, as well ase the voltage and current of the protection point of each manufacturer. are also different, so the products on the market There are many lithium battery protection IC chips, various major solutions, including mobile power solutions, etc. As a person engaged in the lithium battery industry, it is more important to understand which materials and battery materials IC Price for which the chip parameters in the market are used, to choose according to the different process requirements, which are based on the accumulation of experience.
This article comes from Shenzhen Maifeng Electronic Technology website
Working principle:
After connecting the charger to the mobile phone and the socket , the voltage is adjusted through the resistor, enters the voltage comparator with a small value, and outputs a nominal value, which is the normal charging of the mobile phone. LWhen the mobile phone is fully charged, a higher voltage at the other end enters the voltage comparator and outputs 0V. At this time, the relay draws the armature to disconnect the circuit and realize automatic power off.