Nicad Battery Charger

This is so useful circuit for you .Because you can charge your Nicad Batteries by using this circuit.And the other advantage is this circuit is a low cost circuit.Try this.....

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Car Battery 12v Charger

The usual chargers of battery automotive, are simple and cheap appliances that charge continuously the battery, with a rythm of few amperes, for the time where the appliance is ON. If the holder do not close in time the charger, the battery will overcharge and her electrolytic faculty are lost with evaporation or likely exists destruction of her elements. The charger of circuit exceeds these faults. It checks electronic the situation of charge of battery and it has circuit of control with retroaction, that forces the battery charge with biggest rythm until charge completely.

Circuit diagram:

Car Battery 12v Charger Circuit Diaram

When charge completely, it turns on one RED led (LD2). The charger has been drawn in order to charge batteries of 12V, ONLY. What should watch it from what it manufactures the circuit, they are the cables that connect the transformer with the circuit and in the continuity the battery, should they are big cross-section, so that heat when it passes from in them the current of charge and also they do not cause fall of voltage at the way of current through them.

Adjustment

After assembling of the circuit, adjust TR1 to null value, power-up and make the following adjustments :-

1. Without connecting the battery check that the 2 LED?s are turned on.
2. Connect a car battery to the circuit and check that LD2 is OFF and a current (normally 2A to 4A) is flowing to the battery.
3. Adjust TR1 until LD2 turns ON and the charge current is cut.
4. Adjust TR1 to null value and charge the battery using the hydrometer technique (if you do not have or do not know how to use a hydrometer, then use a good condition battery and charge).

Carefully adjust TR1 so that LD2 begins to turn ON and the charge current falls to a few hundred milliamps (mA). If TR1 is set correctly then in the next round of charging you will noticed LD2 begin to flicker as the battery is being charged. When battery is completely charged, LD2 turns ON completely.TR1 does not need further adjustment anymore. Q1 is connected in line with the battery and is fired by R3, R4 and LD2. The R2, C1, TR1 and D2 sense the voltage of the battery terminal and activate Q2 when the voltage of the battery terminal exceeds the value predetermined by TR1.

When an uncharged battery is connected, the terminal voltage is low. Under this circumstance, Q2 is turned OFF and Q1 is fired in each half cycle by R3, R4 and LD2. The Q1 functions as a simple rectifier and charges the battery. If the battery terminal voltage is increased above the level that had been fixed by TR1, then Q2 shifts the control of Q1 gate. This deactivates Q1 and cuts off the current supply to the battery and turns LD2 ON indicating that the charge has been completed. Q1 and bridge rectifier GR1 should be mounted on heatsinks to prevent overheating. M1 is a 5A DC ammeter to measure the charge current.

Source :users.otenet.gr

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Simple L200 Charger

This circuit came about as the result of an  urgent need for a NiMH battery charger. No  suitable dedicated IC being immediately to  hand, the author pressed an L200 regulator and a 4.7 kΩ NTC thermistor into service.  Those components were enough to form the  basis of a charger with a cut-of f condition  based on cell temperature rise rather than  relying on the more common negative delta-V detection.

L200 Charger Circuit Diagram :

The circuit uses the L200 with the thermistor in the feedback loop. When ‘cold’ the  output volt age of the regulator is about 1.55 V per cell; when ‘warm’, at a cell temperature of about 35 °C to 40 °C, the out-put voltage is about 1.45 V per cell and the  thermistor has a resistance of about 3.3 kΩ.  This temperature sensing is enough to pre-vent the cells from being overcharged. P1  adjusts the charging voltage, and R2 limits  the charge current to 320 mA. The IC is fitted with a small 20 K/W heatsink as it dissipates around 1.2 watts in use.

The charger circuit can be connected permanently to the battery pa ck . Charging  starts when a ‘ wall wart ’ adaptor is connected to the input of the charger. The unregulated 12 V supply used by the author  delivered an open- circuit voltage of 18 V,  dropping to 14 V under load. Even though  the charge voltage is reduced when charging is complete, the cells should not be left  permanently on charge.

The author uses the circuit to charge the battery in a torch. After three years and some 150  charge cycles the cells are showing no signs of losing any capacity.

Link : http://www.ecircuitslab.com/2012/08/l200-charger-circuit.html

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Solar Inverter Charger Circuit for Science Project

The following article explains a simple solar inverter circuit consisting of its own battery charger and an automatic changeover relay system for switching the battery to the inverter in the absence of solar energy. The circuit was requested by Ms. Swati Ojha.

The design:

The circuit mainly consists of two stages viz: the inverter, and the automatic relay changeover.

During day time for so long the sun light remains reasonably strong, the panel voltage is used for charging the battery and also for powering the inverter via the relay changeover contacts.

The automatic changeover circuit preset is set such that the associated relay trips OFF when the panel voltage falls below 13 volts.

The above action disconnects the solar panel from the inverter and connects the charged battery with the inverter so that the output loads continue to run using the battery power.

Circuit Description:

Resistors R1, R2, R3, R4 along with T1, T2 and the transformer forms the inverter section. 12 volts applied across the center tap and the ground starts the inverter immediately, however here we do not connect the battery directly at these points, rather through a relay changeover stage.

The transistor T3 with the associated components and the relay forms the relay change over stage  The LDR is  kept outside the house or at a position where it can sense the day light.

 The P1 preset is adjusted such that T3 just stops conducting and cuts off the relay in case the ambient light falls below a certain level, or simply when the voltage goes below 13 volts. This obviously happens when the sun light becomes too weak and is no longer able to sustain the specified voltage levels.

However as long as sun light remains bright, the relay stays triggered, connecting the solar panel voltage directly to the inverter (transformer center tap) via the N/O contacts. Thus the inverter becomes usable through the solar panel during day time.

The solar panel is also simultaneously used for charging the battery via D2 during day time so that it charges up fully by the time it gets dusk.

The solar panel is selected such that it never generates more than 15 volts even at peak sun light levels.

The maximum power from this inverter will not be more than 60 watts.


A MOSFET  based solar inverter can be witnessed HERE

Parts List for the proposed solar inverter with charger circuit intended for science projects.

R1,R2 = 100 OHMS, 5 WATTS

R3, R4 = 15 OHMS, 5 WATTS

T1, T2 = 2N3055, MOUNTED ON SUITABLE HEATSINK

TRANSFORMER = 9-0-9V, 3 TO 10 AMPS

R5 = 10K

R6 = 0.1 OHMS 1 WATT

P1 = 100K PRESET LINEAR

D1, D2 = 6A4

D3 = 1N4148

T3 = BC547

C1 = 100uF/25V

RELAY = 9V, SPDT

LDR = ANY STANDARD TYPE

SOLAR PANEL = 17 VOLTS OPEN CIRCUIT, 5 AMPS SHORT CIRCUIT CURRENT.

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Automatic Batteray Charger

This circuit basically is consisted of a comparator, that monitors reference tension which permanent. If battery tension exceeds maximum level which has in determining before all, relay would be active and will stop charging current. If battery tension went down under its low threshold value, relay is discharged causing enables reenter charging current.


Comparator formed by operation amplifier IC 741. Power allowance tension for amplifier Opamp stabilized by R8 and D4, so that is not influenced by stress variation of battery. Reference tension for operational amplifier alighted from power allowance is stabilized this through R7 and D3. Reference tension compared to a part of battery tension, what taken away from voltage divider R9/R10/R11.

For tuning of tension at R10 enters don’t tumble operational amplifier will become height, makes Q1 and Q2 on, causing activates relay and breaks current pegisian to battery. This aflame LED indicates that battery has been full loaded. To prevent battery connected returns to admission filling if there is the voltage drop a few, hence some of output tensions of operation amplifier is baited to input don’t tumble through R5 and R6. So thereby the operational amplifier is functioning equal to schmitt.

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Computer Power Supply for Battery Charger

Some workbenches can’t help ending up looking like a rats nest of cables and equipment, so its always an advantage if a piece of mains equipment can be removed from somewhere to free up an extra mains socket. Here we are using the ubiquitous PC as a battery charger. An unused serial interface port can supply enough current to charge (or trickle charge) low-capacity Nickel Cadmium (NiCd) batteries. You could for example, use the batteries in a radio and charge them during use.

The three serial port connections TxD, DTR, and RTS, when not in use, are at –10 V and can supply a current of around 10 to 20mA (they are short-circuit protected). The circuit shown supplies a charging current of approximately 30mA. If it is necessary to alter the polarity of the charging circuit then it is a simple job to reverse the diodes and using software, switch the port signals +10 V. Those interested could also write a software routine to automatically recharge the batteries.

Source : www.extremecircuits.net

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