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20 Mar 2011

Microchip’s MCP79411 general purpose I2C™Compatible real-time clock/calendar (RTCC) is highly integrated with nonvolatile memory and advanced features including a battery switchover circuit for backup power, a timestamp to log power failures and digital trimming for accuracy. It can use a low-cost 32.768 kHz crystal or other clock source and the chip operates over a supply range of 1.8 to 5.5 volts. [via]

MCP7941X I2C RTCC with EEPROM, SRAM, Unique ID and Battery Switchover – [Link]

16 Mar 2011

An introduction to USB battery charging: a survival guide. [via]

Arguably the most useful part of USB’s power capabilities is the ability to charge batteries in portable devices, but there is more to battery charging than picking a power source, USB or otherwise. This is particularly true for Li+ batteries, where improper charging can not only shorten battery life, but also can be a safety hazard. A well-designed charger optimizes safety and the user experience. It also lowers cost by reducing customer returns and warranty repairs. Charging batteries from USB requires balancing battery “care and feeding” with the power limitations of USB as well as the size and cost barriers ever present in portable consumer device designs. This article discusses how to achieve this balance.

The basics of USB battery charging: a survival guide – [Link]

15 Mar 2011

Seeed Studio has posted a guide to powering your projects off the grid. Battery, wind, hydro, solar, they’ve got it covered. [via]

Guide to powering your projects off the grid – [Link]

13 Mar 2011

Microchip announced the expansion of its analog power-management family with the MCP73831 battery charger, a fully-integrated, single-cell, Li-ion/Li-Polymer charge-management controller. Tiny 500mA linear charge management controller can be powered directly from the USB port. Includes integrated pass transistor, current sense and reverse-discharge protection, the MCP73831 charger reduces the number of components needed for battery-charger designs. Its highly accurate, pre-set voltage regulation (maximum accuracy 0.5 per cent to 0.75 per cent) results in more fully charged batteries and extended battery life. Since the MCP73831 charge-management controller includes a pass transistor, current sense and reverse-discharge protection on a single chip, it reduces the number of system components needed for battery-charger designs, which, added Microchip, lowers overall system costs.

Microchip’s Li-ion battery charger MCP73831 IC – [Link]

5 Mar 2011

The circuit can be used to charge 12V lead acid batteries.

Pin 1 of the LM317 IC is the control pin which is used to control the charging voltage, Pin 2 is the output at which the charging voltage appears, Pin 3 is the input to which the regulated DC supply is given.

Battery Charger Circuit – [Link]

9 Feb 2011

Here’s a circuit by Joe Desbonnet’s Random Tech Stuff that’s designed to monitor battery voltage. It uses one resistor, one diode (or LED), one microcontroller ADC input and one digital output. [via]

PIC 12F675 battery monitor using a diode/LED and resistor – [Link]

7 Feb 2011

This project is an intelligent battery charger based on PIC16F628.

PIC16F628 intelligent battery charger- [Link]

6 Feb 2011

Check out the MAX8934G dual-input Li+/Li-Poly linear battery charger: [via]

  • Monitors temperature to ensure safe charging and JEITA battery charging specification compliance
  • Delivers smart power path control to allow the system to be powered when the battery is completely dead
  • Charges safely by lowering the termination voltage and charge rate in hot or cold temperature
  • Includes all integrated MOSFETs

MAX8934G dual-input linear Li-Poly battery charger – [Link]

4 Feb 2011

Interesting article from IEEE Spectrum about the potential benefits of developing a usefully rechargeable lithium-oxygen cell (for use, most importantly, in electric cars) and the challenges that remain for that research. So-called “air batteries,” in which one of the reacting chemical species is atmospheric oxygen, are already widely employed, for instance, in hearing-aid batteries, which are commonly zinc-air cells with a piece of adhesive film that must be removed before use to allow atmospheric oxygen onto the cathode. The know-how to make lithium-air cells is available right now; the hard part is making the reverse process practical over many recharging cycles. [via]

The quest for a rechargeable lithium-air battery – [Link]

18 Jan 2011

Mrfixits writes:

This Valentine instructable shows a pair of Hearts that unite to become one! The homopolar motor is the simplest form of electric motor, consisting of a battery, a conductor, and a magnetic field. The flat Heart shape is the most basic of homopolar motors. The Heart with legs is the next most simple shape. With a little ingenuity, the two shapes can be combined to unite into one spinning body. In this Instructable, I show how to make this special 2-piece homopolar motor with a bass speaker, some coins, a battery and two pieces of copper wire. A neodymium magnet can also be used instead of the bass speaker and coins. This is a great display for Valentines Day…or any day of the year!

How-To: Valentine motor - [Link]





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