Universal Battery Charger Battery charger for general purpose usage. Universal Battery Charger circuit diagram The charger's output voltage is adjust

Universal Battery Charger

Battery charger for general purpose usage.

The charger's output voltage is adjustable and regulated, and has an adjustable constant-current charging circuit that makes it easy to use with most NiCad batteries. The charger can charge a single cell or a number of series-connected cells up to a maximum of 18V.

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

12 V SLA battery Charger circuit with explanation

It is a 12 V SLA (Sealed Lead Acid) battery charger circuit

ref : http://www.talkingelectronics.com/projects/BatteryCharger-12vSLA/BatteryCharger-12vSLA.html

Alkaline Battery Charger circuit with explanation

This circuit was specifically designed to recharge alkaline cells. The unusual connection of the transistor in each charging unit will cause it to oscillate, on and off, thus transferring the charge accumulated in the capacitor to the cell. The orange LED will blink for around 5 times a second for a 1.37V cell. For a totally discharged cell the blinking is faster but it will decrease until it will come to a stop when the cell is charged. You may leave the cell in the charger as it will trickle charge and keep it at around 1.6V. To set the correct voltage you have to connect a fresh, unused cell and adjust the trimmer until oscillations set in, then go back a little until no oscillation is present and the circuit is ready to operate. You should use only the specified transistors, LED colors, zener voltage and power rating because they will set the final voltage across the cell. A simple 9V charging circuit was also included: it will charge up to around 9.3V and then keep it on a trickle charge: the green LED will be off while charging and will be fully on when the battery is close to its final voltage.

A 2.5VA transformer will easily charge up to 4 cells at the same time although 2 only are shown in the schematic. In order to minimize interference from one circuit to the other they have nothing in common except the transformer and, in order to show a balanced load to the transformer, half of the charging units will use the positive sinewave and the other half the negative sinewave. Make sure to use high beta transistors such as BC337-25 or better BC337-40. Given the dispersion of the transistor parameters it might happen that oscillations do not take place. Use a slightly higher zener voltage: 7.5V instead of 6.8 or a green led in place of the orange ones.

All types of alkaline cells can be recharged: it will take 1 day for a discharged AA cell or 9V battery and up to several days for a large D type cell. The best practice is not to discharge completely the cell or battery but rather to give a short charge every so often although admittedly this is not easy to achieve. Do not attempt to recharge a totally discharged cell or a cell showing even the slightest sign of damage.

I tried successfully to recharge NiMH cells as well. Although the charging profile for these cells is quite different from alkaline cells, the circuit seems to work fine provided you do not leave them in the charger forever, because of the possibility of overcharging especially for the smaller batteries.

The mains transformer must be suited for the voltage available in each country: usually 230Vac or 115Vac.

By Using transistror Create a 12v battery charger

A very simple 12v battery charger circuit can be designed using a TIP3055 power transistor to limit the current to the battery by turning off when the battery voltage reaches approx 14v or if the current rises above 2 amp.

This battery charger electronic circuit is very simple and require few external electronic parts . Signal to turn off the TIP3055 transistor comes from two other transistors , the BC557 and BC 547. Firstly, the circuit turns on fully via the BD139 and TIP3055. The BC557 and BC 547 do not come into operation at the moment.
As the battery voltage rises, the voltage divider made up of the 1k8 and 39k creates a 0.65v between base and emitter of the BC557 and it starts to turn on at approx 14v.
The input voltage required by this charger electronic circuit project must be around 15 volts DC.

Paper-based batteries to power electronics

Scientists are working hard to develop paper-based batteries made from algae to power electronics in the coming decades. The batteries used now are made off metals, which cause pollution once they are thrown away. Also these batteries are big in size and expensive. Not at all environmentally friendly too. So the people behind the research are aiming at developing a battery from non-metal parts which is having the following properties:

i) Thin

ii) Flexible

iii) Lightweight

iv) Inexpensive

v) Environmentally friendly

Structure of Algae Battery:

Conducting polymers: (most promising materials for these batteries but…)

Can be used for developing batteries with the above mentioned properties. But their ability to hold a charge often degrades over use.

Green algae known as Cladophora:(a solution to the above problem…)

The above figure shows the cladophora algae. This algae makes a special kind of cellulose, which is having a very large surface area. Almost 100 times compared to the cellulose found in paper.

This large surface area dramatically increase the amount of conducting polymer available for use in the new type of battery, enabling it to better recharge, hold and discharge electric charge.

Advantages:

The algae batteries consist of extremely thin layers of conducting polymer, just 40 to 50 nanometers.

The algae batteries can store 50 to 200 percent more charge as compared to similar conducting polymer batteries.

The algae batteries can be recharged much faster than conventional rechargeable batteries.

Recharge time is eight minutes to just 11 seconds.

The algae batteries have greater ability to hold a charge over use.

The algae batteries showed just a 6 percent loss of charge through 100 charging cycles.

Algae battery applications and other properties read more at:

.coreelectronics.