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17 Jun 2013


Testing laptop battery: pinout, SMBus, charge capacity @ KuzyaTech.

As a result of visiting Hamfest, I ended up with a laptop to take apart – a fairly new Toshiba Satellite C675D with a broken screen. It’s not a Hamfest if you don’t bring home something to take apart of course! Today we’ll be testing the battery it came with to see if it’s salvageable.The date code says it was made in 11/2011.


Testing laptop battery: pinout, SMBus, charge capacity - [Link]

14 May 2013


Battery-Charging Controllers for Energy Harvesters by Jon Gabay:

Whether your energy harvesting application uses large solar panels with high voltages and currents or, more often the case, must make do with minute amounts of power derived from various other ambient energy sources, one thing is almost certain: some type of energy storage is on board, whether in the form of a small rechargeable lithium ion battery, a supercapacitor, or solid-state energy storage technology. For the engineer this means that not only do we need to design circuits to harvest and convert ambient energy, but we also have to include an energy-harvesting interface (and protection circuitry) as well as a charge controller. This article looks at single chip energy harvesting devices that also provide some form of charge control. It discusses the different conditions under which energy can be extracted as well as what to expect when trying to squeeze power out of the ambient environment. Finally, the article will present some typical integrated solutions for small-sized low-power energy-harvesting designs.

Battery-Charging Controllers for Energy Harvesters - [Link]

5 Feb 2013


mic @ wemakethings.net writes:

For a long time I wanted to enter the 21st century by stopping using NiCad or NiMH batteries and upgrading to Lithium accumulators as they provide more power per volume and are cool in general. Constant flow of obsolete cell phones provides a nice source of reasonably high-performance batteries for free – I felt compelled to tap into this resource for my battery operated projects.

Open source Lithium battery charger modules - [Link]

4 Feb 2013


Kennith needed a 1A constant current lead-acid battery charger for his HAM radios so he writes:

Since the SLAs are relatively small, and I only need them charged between radio outings, I opted to build a 1A constant current charger, based on the 555 Battery Charger which won first place in the 555 Design Contest Utility category. Using a 555 is a rather clever way to get two comparators and a Set-Reset latch in a single 8DIP package, which is needed for the high and low trip points. The major difference between my design and Mike’s is that instead of using a relay like him, I use an LM317 as a constant current source to limit my batteries charge rate.

555 based constant current lead-acid battery charger - [Link]

8 Jan 2013


With the new AIR 40 wind turbine it is possible to gain 40 kWh monthly – easily and safely. 

Advantages / Features:

  1. high quality wind turbine with 12, 24 or 48V output voltage
  2. 40 kWh monthly at an average wind speed of 5.8 m/sec
  3. operation at 3.1-22 m/s wind speeds
  4. microprocessor based controller
  5. aluminium body
  6. composite blades optimized for a quiet operation
  7. 1.17m rotor diameter
  8. electronic overspeed protection
  9. brushless alternator (dynamo) with a long lifetime

Small wind turbines are an excellent electric energy source for all „off-grid“ applications with a low and middle power consumption like telecommunications, lighting, SCADA (telemetry) and other. In comparison to photovoltaic panels, they require only a very simple installation – to tighten to a shaft.

AIR 40 are top quality microprocessor controlled wind turbines with a precise mechanical construction. Thanks to a low weight and an integrated controller, they´re easy to install and provide an energy right after the installation.   Composite blades are optimized for a quiet operation, durability and a maximum power in a wide range of wind speeds. A big advantage of Air 40 is a relatively low start-up wind speed – already from – 3.1 m/s. „The heart” of  AIR 40 is a brushless alternator dynamo with permanent magnets and with a long lifetime.

Output power of AIR 40 depends from real on-site conditions, however in average it is able to provide 40 kWh monthly, at an average wind speed of 5,8 m/s (21km/h). At higher wind speeds it can be even substantially more. Wind turbines are capable of a standalone operation and they´re also a well-proven complement of PV panels, where they conveniently supplement a decreased power of PV panels, especially in winter season.
Detailed information will provide you the AIR 40 datasheet. In case of interest, please contact us at info@soselectronic.com.

Catch the wind into a net (or into a battery) - [Link]

15 Dec 2012


Bryon Moyer writes:

The development of wireless sensing technology has made possible tasks that would have been unthinkable in years past. Sensors can be installed where it is impractical or impossible to run a communication wire; their ability to communicate wirelessly, as long as they are within range of a hub, means that it is possible to gather data in places or situations that were previously inaccessible.

The inability to run a communication wire to the sensor also means no power line as well. Sensors need power both to sense and to communicate, so that has typically meant using a primary battery. While you would presumably select a battery with as long a life as possible, the battery is still unlikely to outlast the life of the sensor, meaning that someone will have to go out and replace the battery at some point – which can be expensive.

Managing the Energy and Lifetimes of Thin-Film Batteries - [Link]

12 Dec 2012


Stephen Evanczuk writes:

Lithium-ion batteries have emerged as a common energy-storage device in many energy-harvesting applications. For engineers, maximizing battery performance and lifecycle requires use of battery charging circuitry able to account for the specialized characteristics of Li-ion cells. Engineers can cost-effectively build in Li-ion-charging functionality using available ICs from manufacturers including Analog Devices, Diodes Inc., Fairchild Semiconductor, Fujitsu Semiconductor, Intersil, Linear Technology, Maxim Integrated, Micrel, Microchip Technology, and Texas Instruments.

Unlike many other battery technologies, Li-ion cells require a charging profile maintained within a tight envelope. An undercharged Li-ion battery simply cannot provide its full rated energy output. On the other hand, charging circuits cannot afford to push Li-ion battery voltage above recommended limits or apply charging currents that exceed manufacturer-recommended levels. In either case, application of overvoltage or excessive charging current begins to break down Li-ion cells, reducing overall battery life or even resulting in catastrophic failures. For engineers, the challenge is maximizing charging rate and cell voltage without overcharging the cells.

Constant-Voltage/Constant-Current Devices Optimize Li-Ion Battery Charging for Energy-Harvesting - [Link]

4 Dec 2012

circuitsdiy.com writes:

This is a simple li-ion charger without a dedicated li-ion charger IC. This circuit can be used to efficiently and intelligently charge any single cell Li-ion battery pack like mobile battery, digicam battery, etc.


  • Charging via mini-USB connector which is very common.
  • Charging status display by LED
  • Simple circuit by using opamp, resistor, and not by any complex dedicated IC or micro-controller.
  • Charges completely drained (0V) battery packs.
  • Max charging current 500mA (limited by USB supply), depending on battery.

Simple USB DIY Li-ion battery charger - [Link]

23 Nov 2012

Planning on powering that next über-low-power board of yours from a measly CR2032 coin cell?  Read this app note to understand exactly what the limitations of coin cells are: [via]

When designing a small wireless sensor node to be powered by the popular CR2032 coin cell, some sources claim there is a 15mA “limit” and that drawing more current is not possible or will “damage” the battery. This may give the impression that at 15mA everything works perfectly and battery capacity is great, while at 16mA nothing works. There is little public information available to explain why such a limit exists (if it indeed does exist), and little information explaining why 15mA would be a “magic number”.

Understanding Coin Cell Limitations - [Link]

23 Oct 2012

Maxim describes various SMPS regulator topologies for battery powered systems. Isolated and non-isolated topologies are covered:

This tutorial presents an overview of regulator topologies for battery-powered equipment. The discussion covers linear regulators, charge pumps, buck and boost regulators, inverters, and flyback designs. The importance of peak current is explained, and schematics of each topology are shown.

Switch mode regulators for battery powered systems - [Link]





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