Improved solar charged

Energy & Sustainability Technology
Improved solar charged

Here’s an improved Atmel ATtiny13V solar charger, source and schematic included, Dick writes – “Batwatch is a simple monitor for a solar panel battery charger, using an Atmel ATtiny13V. It periodically measures the charge current and battery voltage, and shows them by blinking two LEDs. I built this circuit into the plug of a VW solar charger panel that is used to prevent a discharge of the battery when a car is not used for some time. A modern car contains a large amount of electronics, and a quiescent current of 40-50mA (about 1Ah per day!) is considered “normal”.

Because I wanted to keep an eye on the battery condition and charge current without opening the car, I devised a circuit that shows the voltage and current visually, by blinking a red and green LED. The charge current is determined by measuring the voltage drop over a 10 ohm series resistor. Two A/D inputs are used to measure the voltage before and after the resistor, which is the battery voltage.” [via] – Link.


  • Atmel AVR projects – Link.
  • Open source Atmel AVR microcontroller kits… – Link.
  • Build a $19 AVR Butterfly MP3 player – Link
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