The 12V battery charger circuit diagram

First of all, we need a 12V battery charger circuit diagram. In accordance with the drawings can be clear and convenient to begin production.

To prepare the required materials, firstly, one AC transformer with output AC 12V5-15A, one 6-10A high power rectifier diode, one 25V2200uf capacitor tube, one low voltage power supply control switch and one 220V power plug, insulation tape 1. In addition, a rubber hose with a diameter larger than the diameter of the high-power rectifier diode of 0.3cm30-50cm (water leakage type, rectifier diode cooling) and one plastic empty bottle (for rectifier diode cooling) are required.

Connect the 220V power plug and the transformer input end with wires, and wrap the connector with insulating tape. Because the AC power supply has no positive and negative poles, the input end is connected casually, but the input end and the output end must not be mistaken. The input and output on the transformer must be clearly seen.

Connect the ends of the rectifier diodes with the same length of wire, but the total length should exceed the length of the 30-50cm rubber hose, and then one end passes through the 30-50cm rubber hose, so that the rectifier diode is in the middle of the rubber hose. .

Connect one wire of the transformer 12V output terminal and the positive (or negative) terminal of the rectifier diode with wires and wrap the connector with insulating tape.

Homemade 12v battery charger

Connect the other line of the transformer 12V output terminal to the positive (or negative) terminal of the capacitor tube. The negative (or positive) terminal and the rectifier diode negative (or positive) terminal are connected by wires, and the connector is wrapped with insulating tape.

Homemade 12v battery charger

Then connect the positive and negative ends of the capacitor tube to the wire (lead wire, that is, the wire at both ends of the battery), connect the low-voltage power control switch to the positive terminal and connect the wire to the negative terminal, and wrap the connector with insulating tape.

The 12V battery's termination charge voltage (limit voltage) is 14.4V. Adjust the potentiometer so that the potentiometer midpoint is -(14.4V+0.7V).

The sampling transistor can use ordinary low-power PNP type triode, and the power output tube should use high-power NPN type triode.

Charging process analysis:

1. Maintenance charging:

When the battery voltage is low (can be set, this circuit is preset below 9V), the charger works in the small current maintenance charging state, the working principle is that the U9 pin (in-phase terminal) potential is lower than 8 feet (inverting end) , U output low potential, T4 cutoff. U1D11 foot potential is about 0.18V. At this time, the charging current is about 250mA (the constant current circuit is composed of peripheral circuits of R14, U1D, T1B, and the constant current principle is analyzed by itself).

2. Fast charging:

As the maintenance charge continues, the battery voltage gradually rises. When the battery voltage exceeds 9V, the charger turns into the high current fast charge mode. The U9 pin (in-phase terminal) has a potential higher than the 8-pin (inverting end), and the U output is high. The potential, T4 is on, the U1D11 pin potential is about 0.48V, and the charger constantly outputs about the current to charge the battery.

3. Pressure limiting float:

When the battery is nearly fully charged, the charger automatically switches to the voltage-limited floating state (the voltage-limiting float voltage is set to 13.8V, if it is a 6V battery, the float voltage should be set to 6.9V). The charging current will gradually drop from the fast charging state, and after the battery is fully charged, the charging current is only 10 to 30 mA, which is used to supplement the battery's power loss due to self-discharge.

4. Protection and charging indicator circuit:

The circuit is provided with a reverse polarity protection circuit, which is composed of D4, U, U1D, T1 and peripheral components. When the battery is reversely connected, the charger limits the output current without causing an accident. The charging indication is composed of U, D7 and peripheral components. When charging, D7 lights up, and after the charger enters the floating state, D7 goes out, indicating that the charging is over.

The lithium battery needs to control its charging voltage and charging current during charging and accurately measure the battery voltage. The charging process is divided into four stages according to the lithium battery voltage. Phase one is pre-charging, first pre-charging the lithium battery with a small current of 0.1C, and going to the next stage when the battery voltage is ≥2.5V. In the second stage, the constant current is charged, and the lithium battery is quickly charged with a constant current of 1 C. When the battery voltage is ≥ 4.2 V, the process is shifted to the next stage. Phase III is constant voltage charging, gradually reducing the charging current, ensuring that the battery voltage is constant = 4.2V, and when the charging current is ≤ 0.1C, it goes to the next stage. Phase 4 is trickle charging. After the constant voltage charging is finished, the battery is basically full. In order to maintain the battery voltage, the battery can be recharged with a current of 0.1 C or less, and the charging process of the lithium battery ends.

1. Maintenance charging:

When the battery voltage is low (can be set, this circuit is preset below 9V), the charger works in the small current maintenance charging state, the working principle is that the U9 pin (in-phase terminal) potential is lower than 8 feet (inverting end) , U output low potential, T4 cutoff. U1D11 foot potential is about 0.18V. At this time, the charging current is about 250mA (the constant current circuit is composed of peripheral circuits of R14, U1D, T1B, and the constant current principle is analyzed by itself).

2. Fast charging:

As the maintenance charge continues, the battery voltage gradually rises. When the battery voltage exceeds 9V, the charger turns into the high current fast charge mode. The U9 pin (in-phase terminal) has a potential higher than the 8-pin (inverting end), and the U output is high. The potential, T4 is on, the U1D11 pin potential is about 0.48V, and the charger constantly outputs about the current to charge the battery.

3. Pressure limiting float:

When the battery is nearly fully charged, the charger automatically switches to the voltage-limited floating state (the voltage-limiting float voltage is set to 13.8V, if it is a 6V battery, the float voltage should be set to 6.9V). The charging current will gradually drop from the fast charging state, and after the battery is fully charged, the charging current is only 10 to 30 mA, which is used to supplement the battery's power loss due to self-discharge.

4. Protection and charging indicator circuit:

The circuit is provided with a reverse polarity protection circuit, which is composed of D4, U, U1D, T1 and peripheral components. When the battery is reversely connected, the charger limits the output current without causing an accident. The charging indication is composed of U, D7 and peripheral components. When charging, D7 lights up, and after the charger enters the floating state, D7 goes out, indicating that the charging is over.

Simple 12v charger circuit diagram

Simple 12v charger circuit diagram (2)

For colloidal dielectric lead-acid batteries, this circuit is a high performance charger. The charger is capable of quickly charging the battery and it can be quickly disconnected when the battery is fully charged. The initial charging current is limited to 2A. As the battery current and voltage increase, as the current increases to 150MA, the charger adjusts to a lower floating voltage to prevent overcharging.

Simple 12v charger circuit diagram

Simple 12v charger circuit diagram (3)

As shown in the figure, the circuit consists of a constant current source circuit composed of 7805, which is expanded by a high-power triode.

Simple 12v charger circuit diagram

Simple 12v charger circuit diagram (4)

Whether it's a low current (50 MA) or a high current (1 amp), the circuit is capable. You can choose between manual charging and automatic mode. When the current is very low, you can use a low current before selecting a high current charge. If the battery voltage is too low, Zener diode D5 will have enough current to generate a voltage across R6 to turn Q2 on.

Simple 12v charger circuit diagram

Simple 12v charger circuit diagram (5)

The lithium battery needs to control its charging voltage and charging current during charging and accurately measure the battery voltage. The charging process is divided into four stages according to the lithium battery voltage. Phase one is pre-charging, first pre-charging the lithium battery with a small current of 0.1C, and going to the next stage when the battery voltage is ≥2.5V. In the second stage, the constant current is charged, and the lithium battery is quickly charged with a constant current of 1 C. When the battery voltage is ≥ 4.2 V, the process is shifted to the next stage. Phase III is constant voltage charging, gradually reducing the charging current, ensuring that the battery voltage is constant = 4.2V, and when the charging current is ≤ 0.1C, it goes to the next stage. Phase 4 is trickle charging. After the constant voltage charging is finished, the battery is basically full. In order to maintain the battery voltage, the battery can be recharged with a current of 0.1 C or less, and the charging process of the lithium battery ends.

Simple 12v charger circuit diagram

The system mainly comprises a microcontroller, a voltage detecting circuit, a current detecting circuit, a battery state indicating circuit and a charging control circuit, and the circuit schematic diagram is as shown in the figure.

Simple 12v charger circuit diagram (6)

LM358 (dual operational amplifier, 1 pin is power ground, 8 pin is power positive) and its peripheral circuit provides 12V working power supply D9 provides reference voltage for LM358, after R26, R4 partial pressure reaches LM358 second leg and 5th pin normal When charging, the upper end of R27 has a voltage of about 0.15-0.18V. This voltage is applied to the third leg of LM358 via R17, and a high voltage is sent from pin 1. When the battery voltage rises to about 44.2V, the charger enters the constant voltage charging phase, and the output voltage. Maintaining at about 44.2V, the charger enters the constant voltage charging phase, the current is gradually reduced. When the charging current is reduced to 200mA-300mA, the voltage at the upper end of R27 drops, the voltage of pin 3 of LM358 is lower than 2 feet, and the output voltage of 1 pin is low voltage. Q2 is turned off, D6 is extinguished and 7 feet output high voltage. This voltage makes Q3 turn on all the way, D10 lights up the other way through D8, W1 reaches the feedback circuit, so that the voltage lowers the charger into the trickle charging phase 1-2 hours later. Charging is over.

Simple 12v charger circuit diagram

Simple 12v charger circuit diagram (7)

Lithium-ion battery charger made with 555 time base integrated circuit, which has constant current charging/constant voltage charging automatic conversion function. When the battery terminal voltage is lower than 4.2V, it adopts constant current charging mode, and the battery terminal voltage is charged to 4.2. When V is turned, it will automatically switch to constant voltage and small current (60mA) charging mode, and there will be no overcharging of the battery.

Simple 12v charger circuit diagram

The power circuit consists of a power switch S, a power transformer T, a rectifier bridge stack UR, a filter capacitor C1, C2, and a three-terminal integrated voltage regulator integrated circuit IC1; the charging circuit consists of a diode VD, a three-terminal adjustable voltage regulator integrated circuit IC3, and a resistor R2. ~R4, potentiometer RP2 and control contact of relay K; control circuit consists of time base integrated circuit IC2, potentiometer RP1, resistor R1, R5~R8, capacitor C3, C4, transistor V1, V2, relay K and illuminating Dimensions VL1, VL2.

After the power is turned on, the AC 220V voltage is regulated by T step-down, UR rectification, C1 filtering, and IC1 voltage regulation, and 12V DC voltage is generated at both ends of 02. The voltage is divided into three ways: one step is adjusted by RP1 step-down, and the working voltage (VCC) is provided for 102; one way is added to the 3 pin (voltage input end) of IC3 via VD, as the input voltage of the charging circuit; the other way is through R1 Charge the C3. The operating power supplies for V1, V2, and K are taken from the VDC rectified DC voltage.

When the power is turned on, the voltage at the two terminals of C3 cannot be changed. The voltage of pin 2 of IC2 is lower than VCC/3. The flip-flop inside IC2 is set. The output of pin 3 is high level, so that V1 is saturated and V2 is cut off. Cannot pick up, its normally closed contact is connected, shorting R4, the charging circuit charges the battery GB constant current. At this time, VL2 lights up, indicating that the charger is in a constant current charging state.

When the battery voltage is charged to 4.2V, the voltage of pin 6 of IC2 reaches the threshold level of 2VCc/3, the trigger inside IC2 is reset, the pin 3 changes from high level to low level, so that V1 is cut off and V2 is saturated. K pulls in, its normally closed contact is disconnected, the normally open contact is turned on, and the charging circuit is changed from constant current charging mode to constant voltage charging mode to perform constant voltage charging on GB. The charging current is about 60 MA, and gradually decreases as the charging progresses. When the charging current drops to about 20 MA, the charging is completed.

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