The charging system for a portable device is not always given a high priority in design but it can have a major role in the battery life of the system and, properly optimized, can allow the use of a smaller battery pack than otherwise would be needed. Not only are compact battery-management controllers needed, but intelligence also needs to be deployed tactically to allow the power system to be correctly optimized. This article will look at the needs of the Li-ion chemistry in terms of charging and what techniques can be used to maximize energy delivery and storage and summarize key solutions available for that purpose.
Lithium-Ion Batteries Call for Multi-Cycle Support to Maximize Uptime – [Link]
Determine the power absorbed by the VCVS in the figure. Solution: The VCVS consists of an open circuit and a controlled-voltage source. There is no current in the open circuit, so no power is absorbed by the open circuit. The voltage vc across the open circuit is the controlling signal of the VCVS. The voltage Vc (across 2 ohm resisitor) measures vc to be vc = 2V. The voltage of the controlled voltage source is vd = 2 vc = 4V. The current in the controlled voltage source is 6V/4 ohm= 1.5A. The element current id and voltage vd adhere to the passive convention. Therefore, p = id*vd = (1.5)(4) = 6W is the power absorbed by the VCVS.
Power and Dependent Sources – [Link]
by T.K. Hareendran:
Here is a tried and tested sample circuit of a Li-Ion battery charger that can be used to charge any 3.7V Li-Ion battery using a 5VDC (USB, Solar Panel…) power supply. At the heart of the circuit is one microchip MCP73831, available in SOT-23-5 package. MCP73831 is a highly advanced linear charge management controller for use in space-limited, cost-sensitive applications. This IC employs a constant current/constant voltage charge algorithm with selectable preconditioning and charge termination.
3.7V Li-Ion Battery Charger Circuit – [Link]
by BinksBrew @ instructables.com:
For a long time I’ve had old back up cell phones taking up space in my desk drawer. I was curious if I could put any of these old phones to some use. I can’t just throw them away so I decided to try and re-purpose one of them as a portable charger for my current smart phone.
Portable Charger for your Smartphone – [Link]
You don’t need to travel far in the Dutch countryside before you come across a traditional windmill. Now a consortium of Rotterdam-based companies are planning to build a massive wind-powered generator structure in Rotterdam harbor that will generate energy without using rotating blades. The innovative ‘Windwheel’ will work on the EWICON (Electrostatic WInd energy CONverter) principle developed at TU Delft and Wageningen University backed by a government economy/ecology innovation program.
The striking design has no moving parts but will use wind power to move charged particles (water droplets in this case) against the direction of an electric field. Charge will be transferred to a plate and then fed into the grid. Plans for the proposed generator structure are ambitious and indicate that it will contain a 160-room hotel built on seven floors, 72 residential apartments, a restaurant and other visitor attractions including an outer glass and steel ring structure containing viewing gondolas.
A Bladeless Wind-Powered Generator – [Link]
by DIY Hacks and How Tos @ instructables.com:
A “Joule Thief” is a simple voltage booster circuit. It can increase the voltage of power source by changing the constant low voltage signal into a series of rapid pulses at a higher voltage. You most commonly see this kind of circuit used to power LEDs with a “dead” battery. But there are many more potential applications for this kind of circuit.
In this project, I am going to show you how you can use a Joule Thief to charge batteries with low voltage power sources. Because the Joule Thief is able to boost the voltage of a signal, you are able to charge a battery with a power source whose output voltage is actually lower than the battery itself.
This lets you take advantage of low voltage power sources such as thermoelectric generators, small turbines and individual solar cells.
Joule Thief Low Voltage Battery Charger – [Link]
The LTC®3305 balances up to 4 lead acid batteries connected in series. All voltage monitoring, gate drive, and fault detection circuitry is integrated. The LTC3305 is designed for stand-alone operation and does not require any external control circuitry.
The LTC3305 employs an auxiliary battery or an alternative storage cell to transfer charge to or from each individual battery in the stack. A mode pin provides two operating modes, timer mode and continuous mode. In timer mode, once the balancing operation is completed, the LTC3305 goes into a low power state for a programmed time and then periodically rebalances the batteries. In continuous mode, the balancing operation continues even after the batteries are balanced to their programmed termination voltage.
LTC3305 – Lead Acid Battery Balancer – [Link]
by SparkFun Electronics @ youtube.com:
In today’s episode of “According to Pete,” SparkFun Director of Engineering Pete Dokter is taking a look at homelighting solutions and the SparkFun FemtoBuck LED Driver
SparkFun According to Pete #40: LED Home Lighting and the FemtoBuck Driver – [Link]
TheSignalPathBlog @ youtube.com:
In this episode Shahriar attempts a repair of an Agilent E3642A DC Power Supply which is completely non-responsive. After presenting a teardown of the power supply, the GPIB interface is used to verify the functionality of the power supply. The problem is traced to the main display unit which communicated with the main power supply via a serial interface.
After disassembly of the display, it is revealed that the entire unit has suffered a catastrophic failure due to the VFD display drive IC. All components must be individually removed and replaced. Unfortunately the main processor is a Mask ROM IC version (80C51) and cannot be sourced. Can you help Shahriar find a replacement part?
Teardown, Repair and Analysis of an Agilent E3642A DC Power Supply – [Link]
I bought recently on yahoo auctions a set of 4 gameboys (1 brick, 2 colors and 1 pocket 1st gen) because I had a plan to hack them and I needed some guinea pigs. I have already 2 at home but … well, it was a total of 1,500 JPY (10 euro w/ delivery) so. Got them yesterday morning, quick check: all working modulo the inevitable sticky buttons or gunk that went everywhere after 15 years. Dismantle, wash (water & soap), remove glue (ugly pokemon stickers) and marker (acetone), dry, reassemble. Working fine, nice looking and that vomiting man-sweat smell is gone (previous owner must have had very sweaty hands).
Gameboy battery upgrade – [Link]