Battery Charger Solar Panel Atmel ATtiny13V

Battery Charger Solar Panel Atmel ATtiny13V

Batwatch is a simple monitor for a solar panel battery charger, using an Atmel ATtiny13V. It periodically measures the allegation accepted and array voltage, and shows them by blinking two LEDs. I congenital this ambit into the bung of a VW solar charger console that is acclimated to anticipate a acquittal of the array back a car is not acclimated for some time. A avant-garde car contains a ample bulk of electronics, and a quiescent accepted of 40-50mA (about 1Ah per day!) is advised "normal"

Every brace of seconds, the software samples the two analog inputs, calculates the allegation accepted and array voltage, and shows the voltage on the red LED and the allegation accepted on the blooming LED. The voltage is apparent in units of 0.1V appliance three decimal digits, and the accepted is apparent in units of 10mA appliance two decimal digits. Anniversary chiffre is represented by a cardinal of abbreviate flashes agnate to the amount of the digit. A aught is represented by a distinct best flash. When the allegation accepted is beneath 10mA (after rounding) or negative, the blooming LED is not angry on at all.

I use 4 times oversampling to get an 11-bit result, afterward the address declared in the Atmel appliance agenda AVR121. Im not abiding if there is abundant babble on the inputs to absolutely access the resolution, but it will not aching either. The raw A/D account is adapted to a voltage appliance a abstracted brace of offset/gain constants for anniversary input. These constants are acquired from the arrangement abstracts stored in the EEPROM.

To save power, all delays are implemented by active one or added beddy-bye instructions which account the CPU to abandoned until the abutting timer interrupt. The arrest abundance is 100 Hz, so anniversary beddy-bye pauses up to 10 mS.

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Car Battery Saver Circuit

Prevents the complete discharge of the battery when the door is left open accidentally

I recently forgot to close the door of my car after parking in the garage and I found the battery completely exhausted after the week-end, when I tried to start the engine on Monday morning. This inconvenience prompted me to design a simple circuit, capable of switching-off automatically after a few minutes the inside courtesy lamp, the real culprit for the damage.

Circuit operation:

When the door is opened, SW1 closes, the circuit is powered and the lamp is on. C1 starts charging slowly through R1 and when a voltage of 2/3 the supply is reached at pins #2 and #6 of IC1, the internal comparator changes the state of the flip-flop, the voltage at pin #3 falls to zero and the lamp will switch-off. The lamp will remain in the off state as the door is closed and will illuminate only when the door will be opened again. The final result is a three-terminal device in which two terminals are used to connect the circuit in series to the lamp and the existing door-switch. The third terminal is connected to the 12V positive supply.

Circuit diagram :

Car Battery Saver Circuit Diagram

Notes:

• With the values specified for R1 and C1, the lamp will stay on for about 9 minutes and 30 seconds.
• The time delay can be changed by varying R1 and/or C1 values.
• The circuit can be bypassed by the usually existing switch that allows the interior lamp to illuminate continuously, even when the door is closed: this connection is shown in dotted lines.
• Current drawing when the circuit is off: 150µA.

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Low Cost Universal Battery Charger

Low cost solution for charging of both NiCd and NiMh batteries

Here is the circuit diagram of a low cost universal charger for NiCD - NiMH batteries. This circuit is Ideal for car use. It has ability to transform a mains adapter in to a charger . This one can be used to charge cellular phone, toys, portables, video batteries, MP3 players, ... and has selectable charge current. An LED is located in circuit to indicate charging. Can be built on a general purpose PCB or a veroboard. I hope you really like it.

Picture of the circuit: 

 A Low Cost Universal Charger Circuit Schematic

Circuit diagram:

A Low Cost Universal Charger Circuit Diagram

Parts:

R1 = 120R-0...5W
R2 = See Diagram
C1 = 220uF-35V
D1 = 1N4007
D2 = 3mm. LED
Q1 = BD135
J1 = DC Input Socket

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 …

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.

Example:

To charge a 6V battery a minimum supply voltage of 12V is needed, the maximum voltage is then 15V.

Voltage selection:

Voltage Selection Chart For Low Cost Universal Battery Charger

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.

Caution:

The higher charge current, the more critical the charge time must be checked. When faster charging is used, it is advisable to discharge the battery completely before charging. Using a charge current of 1/10 of the capacity will expand the lifetime of the battery. The charge time can easily be doubled without damaging the battery.

Note:

• Mount the transistor together with the heatsink on the PCB, bend the leads as necessary. Take care that the metal back of the transistor touches the heatsink. Check that the leads of the transistor do not touch the heatsink.

Source : http://www.ecircuitslab.com/2011/08/low-cost-universal-battery-charger.html

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