Battery Splitter Circuit Diagram

Source: http://www.circuitsuggest.com/battery-splitter.html

car battery charger circuit diagram

auto battery charger PCB

Battery Charger Circuit Diagram

Universal Battery Charger Specifications

• Ideal for in car use.
• LED charge indication.
• Selectable charge current.
• Charges Ni Cd or NiMH batteries.
• Transforms a mains adapter into a charger.
• Charge cellular phone, toys, portables, video batteries

Low Cost Charger Features

• LED function indication.
• Power supply polarity protected.
• Supply current: same as charge current.
• Supply voltage: from 6.5VDC to 21VDC (depending on used battery)
• Charge current (±20%): 50mA, 100mA, 200mA, 300mA, 400mA. (selectable)

Determining the supply voltage:
This table indicates the minimum and maximum voltages to supply the charger. See supply voltage selection chart below.

Determining the charge current:
Before building the circuit, you must determinate how much current will be used to charge the battery or battery pack. It is advisable to charge the battery with a current that is 10 times smaller then the battery capacity, and to charge it for about 15 hours. If you double the charge current , then you can charge the battery in half the time. Charge current selection chart is located in diagram.

Example:

A battery pack of 6V / 1000mAh can be charged with 100mA during 15 hours. If you want to charge faster, then a charge current of 200mA can be used for about 7 hours.

From http://www.extremecircuits.net/2009/10/low-cost-universal-battery-charger.html

• 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.
• Constant current can be set as per the battery capacity by using a potmeter and multimeter in series with the battery.
• 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.
• If the battery is discharged below a limit, it will give deep-discharge indication.
• Quiescent current is less than 5 mA and mostly due to zeners.
• DC source voltage (VCC) ranges from 9V to 24V.
• The charger is short-circuit protected.

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 required value.

Adjust 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.

If the battery terminal voltage drops to, say, 11V in case of a 12V battery, adjust potmeter VR3 such that transistor T3 is cut-off and T4 conducts. LED2 will glow to indicate that the battery voltage is low.

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.

Assemble the circuit on a general-purpose PCB and enclose in a box after setting the charging current, overcharge voltage and deep-discharge voltage. Mount potmeters VR1, VR2 and VR3 on the front panel of the box.

Battery Charger Circuit Diagram

Source: http://www.electronicsforu.com

Usually , NiCd batteries must be charged in 14 hours at a charging current equal with a tenth percent from battery capacity. For example, a 500 mAh is charged at 50 mA for 14 hours. If the charging current is too high this will damage the battery.

The level of charging current is controlled with P1 between 0 mA – 1000 mA. T1 is opened when the NiCd battery is connected with the right polarity or if the output terminals are empty. T2 must be mounted on a heatsink.

If you cannot obtain a BD679, then replace it with any NPN medium power Darlington having the output parameters at 30V and 2A. By lowering R3 value the maximum output current can be increased up to 1A.

NiCd Battery Charger Circuit Diagram

NiCd Charger PCB Layout

5V battery type with 4 or 5 cells are charged at 55mA. Again, with P1 adjust the NiCd charger circuit so it disconnects after 14 hours. Window inferior level must be set at 0.8V below this value.

Automatic 9V Battery NiCd Charger diagram

D1 is a protection diode while R1 and C1 decouple the power live of the IC1 U2401B. D3 is for protecting the batteries in case we mount them wrong. R4 limits the current at 5 mA. After we connect the adapter to the main line, the button batteries will start to charge at maximum current for a period of time, after this it will start to charge in impulses. The impulse charging it is always made at 1/10 of the maximum charging current.

R5 = 0,1 * R4
button battery charging time table

Button battery charger circuit diagram

Battery Discharger Circuit Diagram

The battery discharger circuit can be tested with a variable power supply (with current limitator). Connect the discharger circuit at the power supply, adjust the voltage at the desired level at which T1 is blocked. Adjust P1 until D2 lights a bit.
Because the amplification is not too high, there is a zone where D2 goes off gradually and the current decrease gradually. R4 value is calculated for a discharging current of 0.5 A.

Battery Switch Circuit Diagram

Using this battery disconnect switch circuit is simple. To build it in the device, the positive line of the power (battery) to the device must be cut and the circuit (S1 and output) connected in series to this positive line. The ground line of the circuit must be connected to the minus line.

This battery cut-off switch circuit can handle current consumptions up to 150 miliampers. Originally, it was used to control a multimeter.

The setting of each pot is quite critical and must be adjusted repeatedly until the correct threshold level is reached. Finnaly, the pots must be replaced by fixed value resistance values. These resistance values can be found by measuring the actual resistance setting of each pot.

The combination of the LEDs ON condition displays the battery’s condition as shown in the table.

Battery Monitor Diagram