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

The LT3650-8.2 does not require external high-precision resistors to set the float voltage, further saving cost and space. Applications include industrial handheld instruments, 12V to 24V automotive and heavy equipment, desktop cradle chargers and small notebook or tablet computers.

The LT3650 Li-Ion battery charger high operating frequency of 1MHz and current mode architecture allow the use of small inductors and capacitors, minimizing noise and filtering needs. Final float voltage accuracy is specified at ±0.5%, charge current accuracy is ±5% and C/10 detection accuracy is ±2.5%. Once charging is terminated, the LT3650-8.2 automatically enters a low current standby mode that reduces the input supply current to 85uA. In shutdown, the input bias current is reduced to 15uA.

The LT3650-8.2 maximizes battery life during all non-charging periods, draining less than 1uA from the battery. For safety and autonomous charge control, the LT3650-8.2 includes features such as automatic restart and preconditioning, a thermistor input for temperature-qualified charging, programmable input current limit, bad battery detection and binary coded status output pins.

LT 3650 Li Ion battery charger features

• Wide Input Voltage Range: 9V to 32V (40V Absolute Maximum)
• Programmable Charge Current: Up to 2A
• User-Selectable Termination: C/10 or Onboard Termination Timer
• Programmable Input Current Limit
• 1MHz Fixed Frequency
• Average Current Mode Control
• 0.5% Float Voltage Accuracy (8.2V)
• 2.5% C/10 Detection Accuracy
• NTC Resistor Temperature Monitor
• Auto-Recharge at 97.5% Float Voltage
• Bad Battery Detection with Auto-Reset
• Binary Coded Open-Collector Status Pins

LT3650 Li Ion charger applications

• Industrial Handheld Instruments
• 12V to 24V Automotive and Heavy Equipment
• Desktop Cradle Chargers
• Notebook Computers

LT3650 charger circuit diagram

When the voltage is high enough to start the relay and the resistor LDR R2 receives enough solar light to open T1, the relay starts and the battery will charge.
With P1 you adjust the level when the relay acts. Because the current consumption is determined by the relay, it is important that it will be a miniature type, with high coil resistance, but strong enough to comute up to 10A (eg: Siemens V23037-A0002-A101)

Solar panel switching circuit schematic

When the battery voltage level rises, the voltage at the non-inverting input will also rise and by certain level (set with P1) the non-inverting input has a higher level than the inverting input.
The comparator is designed to have a hysteresis that prevents the circuit from “oscillating” (constantly switching on or off the relay) that could be cause by slight changes ti the battery voltage. This hysteresis is set with P2 which also sets the minimum battery voltage level at which the charging resumes.

Automatic battery charger circuit calibration

The best way to calibrate the circuit is to use a variable voltage, regulated power supply. This is connected to the circuit in the place of the NiCad battery. Set the regulated power supply to 14.5 volts and adjust the P1 to a point where the relay snaps open. Newt, set the regulated power supply to 12.4 volts and adjust P2 to a point the relay closes back. You might need to repeat this procedure severals time since P1 and P2 have an effect on each other.

Automatic battery charger circuit diagram

IC1c output is passed through 3 levels: in IC3f, IC3a and the four gates connected in parallel IC3b-IC3e. Then it is used to command t3 FET.
IC1b commands T1 and when this transistor conducts, the common point of R6-R7 will drop at 2V in the absence of D1.
T2 and T3 conducts alternatively. When T2 conducts, C10 charges untill the input signal level through T3 and D3. When T2 is blocked and T3 conducts, C9 is charging in the similar way.
It is essential that D2, D3, T2 and T3 to have a good cooling. For the best, mount them on a common heatsink.

The bold lines represent high currents circuits which must be as short as can be, because it transport up to 6A.
A very well constructed dc to dc converter can have as much as 94% efficiency (at 22.2V and 1.8Amps)

dc converter circuit diagram

Input and output voltages at a 2A load current:

Power transistor Q1 and Q2 are connected as series regulators to control the battery chargers’s ouput voltage and charge-current rate. An LM317 adjustable voltage regulator supplies the drive signal to the bases of power transistor Q1 and Q2. Potentiometer R9 sets the output-voltage level. A current-sampling resistor, R8 (a 0.1Ω 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 decreases. 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.
This can be used as a military battery charger.

Universal battery charger circuit diagram

12 Volts battery charger circuit diagram

Temperature compensation helps prevent overcharging, the LM334 temperature sensor should be placed near or on the battery. Because batteries need more compensation at lower temperatures, change R5 to 30Ω for a tc of -5mV/0C per cell il this circuit will be used at temperatures below – 200C.
The charger’s input voltage must be filtered dc that is at least 3V higher than the maximum required output voltage. Choose a regulator for the maximum current needed: LM371 for 2A, LM350 for 4A, LM338 for 8A. At 250C and with no load, adjust R7 for a Vout of 7.05V, and adjust R8 for a Vout of 14.1V.

Car battery charger circuit diagram

]]> http://ebatterychargers.com/lead-acid-car-battery-charger-20.html/feed/ 4 http://ebatterychargers.com/car-battery-charger-15.html http://ebatterychargers.com/car-battery-charger-15.html#comments Sat, 31 Jan 2009 23:36:17 +0000 eBatteryChargers.com http://ebatterychargers.com/?p=15 Car battery charger circuit review:
Modern acid batteries and plates Pb, are embodiment of simplicity in use. Unlike NiCd batteries, they must be recharged by connecting to a constant voltage. In this situation, the loading current will provide a good indication of the state of loading.

Car battery charger circuit diagram

These batteries can be quickly loaded as long as the loading current is limited even at the beginning of the trial proceedings. The charger which we propose it has a voltage regulator, IC1, and a variable current limiter which consists of T1, R1 and R4. Once the current through R1 becomes too large, T1 is opening and the output voltage decreases. Values, in volts, of output voltage is given by the formula: 1.2 (P1 + R2 + R3) / R3
For a 6V battery, the required load voltage for a rapid loading will be 3 x 2.45 = 7.35V. In this case, the actual total value for R2 + P1 will have to be 585 Ω.
To charge 12V batteries, the amount needed for R2 + P1 should be around 1290 Ω. Voltage at the entrance must be at least 3V larger than that of output.
LM317 integrated circuit needs heatsink, not only for that, otherwise, can easily destroy, but also because, at high temperatures, it can not provide the current maximum output.

12v battery charger PCB

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