This 6V and 12V car battery charger circuit can be automatically charged, quickly and correctly, 6V and 12V batteries. Circuit design is divided into two series of modules that are: power supply module and the main charger module containing the regulator modules and direct current amplifier module.

How the 6V and 12V Car Battery Charger Works

A key factor in the success of the operation of the circuit is the use of good quality transformer [T1]  with very good insulation and resistance to short circuits. The Q1 through divider R1-2, of TR1 and R4, functions as a regulated current source. The current through R9 drives power transistors Q5-6, where amplified approximately x2000 times. In an unloaded car battery voltage is about 6V to 8V. With these conditions, the charge current is about 1.2A [regulated by TR1]. When the battery is charging slowly, gradually increases the voltage at its ends. 7V to enter into the D1 conducts. As the battery voltage increases, the voltage decreases at the ends of R3 Q1 made the most conductive. This continues until the current reaches about 6A. Then by means of the voltage drop across R10, is made conductive to Q4. The excess current to the base of Q5 to ground, keeping the load current constant. When the battery is fully charged [14.4V] activated in parallel to the circuit battery, consisting of R6, D8, D2 to D6. At the same time illuminates the D8 indicating that the battery has been fully charged. Simultaneously Q2 is conducting because the voltage drop on R6. The Q3 is conductive and grounded part of the stream at the base of Q5. When the voltage across the battery reaches approximately 15V current at the base of Q5 is very small, so to stop charging the battery. Diodes D5-6 protect the circuit from accidentally installing the battery or short circuits of long duration. The diode D4 protects the circuit from wrong positioning of the battery terminals. Then D9 Led lights showing connection error [ERROR]. Closing switch S2 short the diode D2 [6.8V], now we can charge 6V battery.

6V and 12V Car Battery Charger Component List

6V and 12V Car Battery Charger  Adjustment

The initial charge current should be adjusted via the TR1 to 1.2A. The adjustment can be done with a 6V battery. Connect in series with the battery a current [maximum 10A]. If there is 6V battery is short-circuited through the ammeter the charger terminals and adjust the TR1 current to 1.2A. When setting the switch S2 should be in the position of 12V, i.e. open. Particular attention should be paid to the accuracy of the diodes D2 and D3 because they protect the battery from overcharging. If the differential voltage is 100mV to go to consider them as acceptable. If you encounter difficulties in the current setting and the TR1 is not enough, you can change the value of the resistor R4, to measure charge current 1.2A. The two parallel resistors constituting R10, should be placed at a distance from the printed and Q5-6, because heated. The bridge B1 and Q5-6 be mounted on heatsink having insulated electrically from this with suitable mica silicone. The bridge B1 and the board in which the circuit is mounted must be connected with short and thick cables, especially where the current is large. lines are also printed on must have the appropriate width [in the project are shown in thicker line]. The construction should be done in a nice metal box, suitable dimensions so there is good ventilation. The construction requires the expertise.

WORK WITH BATTERIES REQUIRE HIGH ATTENTION IN HANDLING BECAUSE THERE IS ALWAYS A RISK OF EXPLOSION.

Power transistors Q1 and Q2 are connected as series regulators to control the battery charger ‘s output voltage and charge-current rate. An LM-317 adjustable voltage regulator supplies the drive signal to the bases of power transistor Q1 and Q2.

Potensiometer R9 sets the output-voltage level. A current sampling resistor, R8 (a 0.1 ohm/5W unit), is connected between the negative output lead and circuit ground. For each amp of charging current that flows through R8, a 100mV output is developed across it. The voltage developed across R8 is fed to one input of comparator U3. The other input of the comparator is connected to variable resistor R10.

As the charging voltage across the battery begins to drop, the current through R8 decrease. Then the voltage feeding pin 5 of U3 decreases, and the comparator output follows, turning Q3 back off, which completes the signal’s circular path to regulate the battery’s charging current.

The charging current can be set by adjusting R10 for the desired current. The circuit’s output voltage is set by R9, adjust the R9 to get the correct voltage output value as needed.

This is the circuit diagram of battery charger which has many important features such as current-constant charging, overcharge protection, short-circuit protection, deep discharge protection and more. The constant-current charging is a popular method for lead-acid and Ni-Cd batteries. In this circuit, the battery is charged with a constant current that is generally one-tenth (1/10) of the battery capacity in ampere-hours. So for a 4.5Ah battery, constant charging current would be 450 mA.

D1 is a low-forward-drop schottky diode SB560 having peak reverse voltage (PRV) of 60V at 5A or a 1N5822 diode having 40V PRV at 3A. Normally, the minimum DC source voltage should be “D1 drop+Full charged battery voltage+VDSS+ R2 drop,” which is approximately “Full charged battery voltage+5V.” For example, if we take full-charge voltage as 14V for a 12V battery, the source voltage should be14+5=19V.

How this battery charger circuit works:

To make the simple explanation, lets divide this battery charger circuit into three sections: constant current source, overcharge protection and deep-discharge protection sections.

Constant Current Source

The constant-current source is built around MOSFET T5, transistor T1, diodes D1 and D2, resistors R1, R2, R10 and R11, and potmeter VR1. Diode D2 is a low-temperature-coefficient, highly stable reference diode LM236-5. LM336-5 can also be used with reduced operating temperature range of 0 to +70?C. Gate-source voltage (VGS) of T5 is set by adjusting VR1 slightly above 4V. By setting VGS, charging current can be fixed depending on the battery capacity. First, decide the charging current (one-tenth of the battery”s Ah capacity) and then calculate the nearest standard value of R2 as follows:
R2 = 0.7/Safe fault current.

R2 and T1 limit the charging current if something fails or battery terminals get short-circuited accidentally. To set a charging current, while a multimeter is connected in series with the battery and source supply is present, adjust potmeter VR1 slowly until the charging current reaches its needed value.

Overcharge Protection

Overcharge and deep-discharge protection have been shown in dotted areas of the circuit diagram. All parts in these areas are subjected to a maximum of the battery voltage and not the DC source voltage. This makes the circuit work under a wide range of source voltages and without any influence from the charging current value. Set overcharge and deep-discharge voltage of the battery using potensiometers VR1 and VR2 before charging the battery.

Deep-Discharge Protection

In overcharge protection, zener diode ZD1 starts conducting after its breakdown voltage is reached, for example, it conducts when the battery voltage goes beyond a prefixed high level. Adjust the variable resistor VR2 when the battery is fully charged (say, 13.5V in case of a 12V battery) so that VGS of T5 is set to zero and hence charging current stops flowing to the battery. LED1 glows to indicate that the battery is fully charged. When LED1 glows, the internal LED of the optocoupler also glows and the internal transistor conducts. As a result, gate-source voltage (VGS) of MOSFET T5 becomes zero and charging stops.

Normally, zener diode ZD2 conducts to drive transistor T3 into conduction and thus make transistor T4 cut-off. If the battery terminal voltage drops to, say, 11V in case of a 12V battery, adjust the potensiometer VR3 such that transistor T3 is cut-off and T4 conducts. LED2 will glow to show you that the battery voltage is in low condition.

Values of zener diodes ZD1 and ZD2 will be the same for 6V, 9V and 12V batteries. For other voltages, you need to suitably change the values of ZD1 and ZD2. Charging current provided by this circuit is 1 mA to 1 A, and no heat-sink is required for T5. If the maximum charging current required is 5A, put another LM236-5 in series with diode D2, change the value of R11 to 1 kilo-ohm, replace D1 with two SB560 devices in parallel and provide a good heat-sink for MOSFET T1. TO-220 package of IRF540 can handle up to 50W.

Built this battery charger circuit on a general-purpose PCB and enclose in general box / cabinet after setting the charging current, overcharge voltage and deep-discharge voltage. Mount the potensiometers VR1, VR2 and VR3 on the front panel of the box.

This battery charger circuit has the following features:

1. It can charge 6V, 9V and 12V batteries. Batteries rated at other voltages can be charged by changing the values of zener diodes ZD1 and ZD2.
2. DC source voltage (VCC) ranges from 9V to 24V.
3. The charger is short-circuit protected.
4. Constant current can be set as per the battery capacity by using a potmeter and multimeter in series with the battery.
5. Once the battery is fully charged, it will attain certain voltage level (e.g.13.5-14.2V in the case of a 12V battery), give indication and the charger will switch off automatically. You need not remove the battery from the circuit.
6. If the battery is discharged below a limit, it will give deep-discharge indication.
7. Quiescent current is less than 5 mA and mostly due to zeners.

EFYmag

This is the circuit diagram of rechargable battery charger which use solar cell / photovoltaic as the DC source. This circuit works to charge 3 types of rechargable batteries that are lead acid, Ni-Cd and Li-ion. The lead-acid batteries are generally utilized in emergency lamps and UPS. The photovoltaic module or solar cell explained in this post is capable of producing a power of 5 watts. At full sunlight, the solar cell outputs 16.5V. It can deliver a current of 300-350 mA.

How the circuit works?

The working of the circuit is quite simple. The output of the solar panel is fed via diode 1N5402 (D1), which acts as a polarity guard and protects the solar panel. An ammeter is connected in series between diode D1 and fuse to measure the current flowing during charging of the batteries. As shown in Image #1, we have used an analogue multimeter in 500mA range. Diode D2 is used for protection against reverse polarity in case of wrong connection of the lead-acid battery. When you connect wrong polarity, the fuse will blow up.

For charging a lead-acid battery, shift switch S1 to “on” position and use connector “A.” After you connect the battery, charging starts from the solar panel via diode D1, multimeter and fuse. Note that pulsating DC is the best for charging lead-acid batteries. If you use this circuit for charging a lead-acid battery, replace it with a normal pulsating DC charger once a week. Keep checking the water level of the leadacid battery. Pure DC voltage normally leads to deposition of sulphur on the plates of lead-acid batteries.

For charging Ni-Cd cells, shift switches S1 and S3 to “on” position and use connector “B.” Regulator IC 7806 (IC1) is wired as a constantcurrent source and its output is taken from the middle terminal (normally grounded). Using this circuit, a constant current goes to Ni-Cd cell for charging. A total of four 1.2V cells are used here. Resistor R2 limits the charging current.

For charging Li-ion battery (used in mobile phones), shift switches S1 and S2 to “on” position and use connector “C.” Regulator IC 7805 (IC2) provides 5V for charging the Li-ion battery. Using this circuit, you can charge a 3.6V Li-ion cell very easily. Resistor R3 limits the charging current. Image #2 shows the circuit for a small LED-based lamp. It is simple and lowcost. Six 10mm white LEDs (LED2 through LED7) are used here. Just connect them in parallel and drive directly by a 3.6V DC source. You can use either pencil-type Ni-Cd batteries or rechargeable batteries as the power source.

Assemble the circuit on a general purpose PCB and enclose in a small box. Mount RCA socket on the front panel of the box and wire RCA plug with cable for connecting the battery and LED based lamp to the charger.

With this circuit, you can save on your electricity bills by switching to alternative sources of power.

This is the circuit diagram of 12 Volts, 4 Amperes Solar Photovoltaic (PV) battery charger which will be suit to charge a 12V battery or accumulator. The circuit handles up to 4 amps of current from a solar panel, which equates to about 75 watts of power. A charging algorithm called “pulse time modulation” is introduced in this design. The current flow from the solar panel to the battery is controlled by an N-channel MOSFET, T1. This MOSFET does not require any heat sink to get rid of its heat, as its RD-S(on) rating is just 0.024 ?.

Components List:

R1 = 15k?
R2,R3 = 3.3k? 1% R4 = 2.2M?
R5 = 1k?
P1 = 5k? preset
C1 = 22uF 25V, radial
D1 = MBR1645G (ON Semiconductor) D2 = LED, 5mm
IC1 = TL431ACLP (Texas instruments)
T1 = IRFZ44NPBF (International Rectifier)
T2 = 2SC1815 (Toshiba) (device is marked: C1815)
T3 = BC547
Miscellaneous:
K1,K2 = 2-way PCB terminal block, lead pitch 5mm

How the circuit works:

Schottky diode D1 prevents the battery discharging into the solar panel at night, and also provides reverse polarity protection to the battery. In the schematic, the lines with a sort-of-red highlight indicate potentially higher current paths. The charge controller never draws current from the battery?it is fully powered by the solar panel. At night, the charge controller effectively goes to sleep. In daytime use, as soon as the solar panel produces enough current and voltage, it starts charging the battery. The battery terminal potential is divided by resistor R1 and trimpot P1.

The resulting voltage sets the charge state for the controller. The heart of the charge controller is IC1, a type TL431ACZ voltage reference device with an open-collector error amplifier. Here the battery sense voltage is constantly compared to the TL431″s internal reference voltage. As long as the level set on P1 is below the internal reference voltage, IC1 causes the MOSFET to conduct. As the battery begins to take up the charge, its terminal voltage will increase. When the battery reaches the charge-state set point, the output of IC1 drops low to less than 2 volts and effectively turns off the MOSFET, stopping all current flow into the battery.

With T1 off, LED D2 also goes dark. There is no hysteresis path provided in the regulator IC. Consequently, as soon as the current to the battery stops, the output of IC1 remains low, preventing the MOSFET to conduct further even if the battery voltage drops. Lead-acid battery chemistry demands float charging, so a very simple oscillator is implemented here to take care of this. Our oscillator exploits the negative resistance in transistors. In this implementation, a commonplace NPN transistor type 2SC1815 is used.

When the LED goes out, R4 charges a 22-uF capacitor (C1) until the voltage is high enough to cause the emitter-base junction of T2 to avalanche. At that point, the transistor turns on quickly and discharges the capacitor through R5. The voltage drop across R5 is sufficient to actuate T3, which in turn alters the reference voltage setting. Now the MOSFET again tries to charge the battery. As soon as the battery voltage reaches the charged level once more, the process repeats. A 2SC1815 transistor proved to work reliably in this circuit. Other transistors may be more temperamental?we suggest studying Esaki”s laureate work to find out why, but be cautioned that there are Heavy Mathematics Ahead.

As the battery becomes fully charged, the oscillator’s “on” time shortens while the “off” time remains long as determined by the timing components, R4 and C1. In effect, a pulse of current gets sent to the battery that will shorten over time. This charging algorithm may be dubbed Pulse Time Modulation. To adjust the circuit you’ll need a good digital voltmeter and a variable power supply. Adjust the supply to 14.9 V, that’s the 14.3 volts battery setting plus approximately 0.6 volts across the Schottky diode.

Turn the trimpot until at a certain point the LED goes dark, this is the switch point, and the LED will start to flicker. You may have to try this adjustment more than once, as the closer you get the comparator to switch at exactly 14.3 V, the more accurate the charger will be. Disconnect the power supply from the charge controller and you are ready for the solar panel. The 14.3 V setting mentioned here should apply to most sealed and flooded-cell lead-acid batteries, but please check and verify the value with the manufacturer. Select the solar panel in such a way that its amps capability is within the safe charging limit of the battery you intend to use.

By: T. A. Babu (India – Elektor)

This is the cell phone shield circuit which can be used as mobile charger. Give protection to your cell phone from unexpected use or theft working with this easy circuit. It is able to produce a loud chirping sound when someone tries to take away the mobile handset. The added function is that the circuit also operates as being a mobile charger.

The circuit is powered by a step-down transformer X1 with rectifier diodes D1 and D2 and filter capacitor C1. Regulator IC 7812 (IC1) together with noise filter capacitors C2 and C3 gives regulated power source.

The cell phone shield circuit uses two NE555 timer ICs: One as being a very simple astable multivibrator (IC2) and then the 2nd as being a monostable multivibrator (IC3). The astable multivibrator has timing resistors R1 and R2 but no timing capacitor since it operates with stray capacitance. Its pins 6 and 2 are directly joined to a safeguarding shield built up of 10cm?10cm copper-clad board.

The inherent stray capacitance of the circuit is enough to supplied an output frequency of about 25 kHz with R1 and R2. This arrangement gives better sensitivity and allows the circuit with hand capacitance effect. Output pulses from the oscillator are immediately assigned to trigger pin 2 of the monostable multivibrator. The monostable utilizes a low-value capacitor C6, resistors R3 and preset VR1 for timing.

The output frequency of the monostable multivibrator is altered utilizing preset/trimmer VR1 such that it is slightly less than that of the astable multivibrator. This makes the circuit standby, as soon as there is no hand capacitance present. So in the standby mode, the astable”s output is going to be low. This tends to make the trigger input of monostable become low and output become high.

The warning indicator buzzer and LED1 are joined such that they come to be active only when the output of the monostable multivibrator sinks current. During the standby state, the LED1 continues to be “off” and also the buzzer is silent. As someone attempts to take the cell phone from the defending shield, his hand comes close to the shield or makes contact with the shield, which introduces hand capacitance within the circuit. Because of this, the astable”s frequency changes, which makes the trigger pin of the monostable become low and its output oscillates. This generates chirping sound from the buzzer and also makes the LED1 blink.

The circuit can even be utilized as being a mobile charger. It delivers output of 6V at 180 mA through regulator IC 7806 (IC4) and resistor R5 for charging the cell phone. Diode D3 defends the output from polarity reversal.

The circuit could be wired on a general PCB. Enclose it inside a appropriate case with provision for charger output leads. Produce the protective shield making use of 10cm?10cm copper-clad board or aluminium sheet. Hook it up towards the circuit working with a 15cm plastic wire. Leads of all capacitors ought to be short.

Fine-tune VR1 little by little working with a plastic screwdriver until eventually the buzzer stops sounding. Get the hand nearby to the shield and fine-tune VR1 right up until the buzzer sounds. With trial-and-error method, set it up for the highest level of sensitivity such that as shortly the hand comes close to the shield, the buzzer begins chirpring and also the LED blinks. As an alternative to applying the copper cladding for shield, a metallic cell phone holder can be utilized as being the shield.

Mobile phone chargers offered in the marketplace are quite expensive. The circuit shown right here shows up as a low-cost option to charge cell phones or battery packs having a rating of 7.2 volts, for example Nokia 6110/6150.

The 220-240V AC mains source is stepped down to 9V AC by transformer X1. The transformer output is rectified by diodes D1 through D4 connected in bridge configuration and the positive DC source is straightly wired to the charger”s output contact, while the negative terminal is connected through current limiting resistor R2.

LED2 operates as being a power indicator with resistor R1 serving as the current limiter and LED3 signifies the charging status. While in the charging period, about 3 volts drop happens across resistor R2, which switches on LED3 through resistor R3.

An external DC supply source (for example, from a automobile battery) may also be applied to energise the charger, in which resistor R4, after polarity protection diode D5, limits the input current to a secure value. The 3-terminal positive voltage regulator LM7806 (IC1) delivers a fixed voltage output of 7.8V DC because LED1 interconnected in between the common terminal (pin 2) and ground rail of IC1 increases the output voltage to 7.8V DC. LED1 also acts as being a electrical power indicator for the external DC source.

After building the circuit on a veroboard, enclose it inside a appropriate cabinet. A little heatsink is highly recommended for IC1.

The schematic diagram shown right here is the automatic switching-on emergency light circuit which is controlled using IC. The most important capabilities of this circuit are: automatic switching-on of the light on main power failure and battery charger with overcharge protection.

When mains electrical power is absent, relay RL2 is in deenergised state, feeding DC source from battery to inverter section via its N/C contacts and switch S1. The inverter section comprises IC2 (NE555) that is applied in stable mode to generate sharp pulses / wave with frequency of 50 Hz to drive the power MOSFETs. The output of IC3 is fed to gate of MOSFET (T4) directly while it is applied to MOSFET (T3) gate just after inversion by transistor T2. Therefore the power amplifier designed close to MOSFETs T3 and T4 functions in push-pull mode.

The output across secondary of transformer X2 can simply drive a 230-volt, 20-watt fluorescent tube. In event light isn’t needed to become on during mains power failure, then just flip switch S1 to off position.

Battery overcharge preventer circuit is designed close to IC1 (LM308). Its non-inverting pin is held at a reference voltage of about 6.9 volts that is obtained implementing diode D5 (1N4148) and 6.2-volt zener D6. The inverting pin of IC1 is connected to the positive terminal of battery. Thus when mains electric supply is present, IC1 comparator output is high, unless battery voltage exceeds 6.9 volts. So transistor T1 is normally forward biased, which energises relay RL1. Within this state the battery stays on charge via N/O contacts of relay RL1 and current limiting resistor R2. When battery voltage exceeds 6.9 volts (overcharged condition), IC1 output goes low and relay RL1 gets deenergised, and thus stops more charging of battery.

MOSFETs T3 and T4 may be mounted on appropriate heat sinks to prevent overheating on the MOSFETs and keep the MOSFETs in good performance.

This automatic switching-on emergency light circuit taken from EFY magazine. The circuit is already tested and should be working properly. This circuit idea available in PDF document, download from the following link:

Automatic Emergency Light Project

1 file(s) 275.55 KB

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Today, a lot of handheld gadgets (for example: portable reading lamps, smartphones, tablets, ipod) utilise this resource of the USB port to recharge their battery pack using the support of an internal circuitry. Typically 5V DC, 100mA electric current is needed to satisfy the input electrical power demand.

The above diagram shows the circuit of a versatile USB power socket that properly converts the 12V battery voltage into stable 5V. This car cigar lighter to USB circuit can make it possible to power / recharge any USB power-operated device. It work with in-dash board cigar lighter socket of the car.

The DC supply presented from the cigarette lighter socket is fed to an adjustable, three-pin regulator LM317L (IC1).

Capacitor C1 buffers any disorder in the input supply. Resistors R1 and R2 regulate the output of IC1 to constant 5V, that is accessible at the “A” type female USB socket. Red LED1 signifies the output condition and zener diode ZD1 acts as a protector against excessive voltage.

Assemble the circuit of car cigar lighter to USB power socket on a general purpose PCB and enclose inside a slim plastic cabinet as well as the indicator and USB socket. Whilst wiring the USB outlet, make sure proper polarity of the supply. For interconnection between the cigar plug pin as well as the device, use a long coil cord as shown in second image.

Here the Pin configuration of LM317L:

Download this car cigar lighter to USB circuit in PDF Version:

USB Power Socket Project

1 file(s) 203.89 KB

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Parts list:
R1 : 1.5 K?
R2 : 3.9 K?
R3 : 10 K?
R4 : 180 ?
R5 : 4.7 K?
R6 : Thermistor 10? PTC
PC1 : 3V solar battery from the battery lamp Landscape
C1 : 22uF/16V
C2 : 100pF
C3 : 10uF/16V
L1 : 50-300 uH choke
D1 : 1N5818 Schottky diode
Q1 : 2N4403 , or equivalent
Q2 : 2N4401 , or equivalent
B1 : Ni-Cad battery, 6V with fuse

Solar powered mobile phone battery charger circuit source: PowerSupply88.com