Can the switching power supply directly charge the battery
Cannot charge directly!
1. If two lithium batteries are connected in series to form 7.2v, then it can be charged up to 3.6*1.16=8.3v
2. If it is a lead-acid battery, it can be charged up to 7.2*1.2=8.6v
Although the original charger outputs 12v voltage, it may be no-load floating voltage, and it will come down as soon as the battery is connected. Your battery is 2000mah, and the charging current is generally between 2000/10--4=200--500ma, which is safe. Although the original charger has a nominal output of 800ma, 12.8v, the power of the switching power supply on the market today is a virtual standard, which needs to be discounted. In fact, the safest current is 1/10=200ma, which is the most fully charged. The service life is also the longest, but the charging time is longer. So your switching power supply output 12v voltage is too high, and it cannot be charged directly without constant current and step-down, and it will really explode.
Another possibility is: the electrical appliance has a charging circuit inside, so the 12v switching power supply can be used by installing the battery in the electrical appliance. Don't worry about the 0.8v voltage difference, it doesn't matter if the current is large , If it is small, it will cause the switching power supply to heat up (just try the temperature of the shell by hand), and burn it down.
Maintenance steps of switching power supply
1. When repairing the switching power supply, first use a multimeter to check whether each power component is broken down and short-circuited, such as the power rectifier bridge stack, switch tube, high-frequency high-power rectifier tube, and whether the high-power resistor that suppresses the surge current is blown. Then check whether the resistance of each output voltage port is abnormal. If these parts are damaged, they need to be replaced.
2. The first step is completed. After the power is turned on, it still cannot work normally. Next, it is necessary to detect the power factor module (PFC) and pulse width modulation module (PWM), consult relevant information, and be familiar with each function of the PFC and PWM module and its modules. A prerequisite for proper functioning.
3. Then, for a power supply with a PFC circuit, it is necessary to measure whether the voltage at both ends of the filter capacitor is about 380VDC. If there is a voltage of about 380VDC, it means that the PFC module is working normally.
Then detect the working state of the PWM component, measure its power supply input terminal VC, reference voltage output terminal VR, start control Vstart/Vcontrol terminal voltage is normal.
4. In the practice of switching power supply maintenance, many switching power supplies use UC38×× series 8-pin PWM components. Most of the power supplies cannot work because the starting resistor of the power supply is damaged or the performance of the chip is degraded.
5. When there is no voltage of about 380VDC on the filter capacitor, it means that the PFC circuit is not working normally. The key detection pins of the PFC module are the power input pin VC, the start pin Vstart/control, CT and RT pins and V0 pin.
