Electronics-Lab.com Blog

Steven Keeping writes:

Lithium-ion (Li-ion) batteries have become popular for portable electronics such as laptop computers and smart phones because they boast the highest energy density (capacity per unit volume) of any commercial battery technology. Other benefits include thousands of recharges and no occurrence of the “memory effect” that plagued early nickel cadmium (NiCd) rechargeable cells.

However, it has been a tough design challenge to get the technology to where it is today. Lithium is a highly reactive material that can, for example, burst into flames if it comes into contact with water. Engineers and scientists have worked hard to develop novel compounds that can leverage the advantages of lithium while producing inexpensive, reliable, and safe batteries.

A Designer’s Guide to Lithium Battery Charging - [Link]

Brian Chu writes:

Batteries often serve as the main energy source for portable electronic devices. Although they depend on batteries, portable consumer electronic products, such as GPS devices and multi-media players, often consume energy directly from an ac-dc wall adapter or accessory power adapter (or “Auto Adapter”) when the battery is low or the device is in a stationary mode. Due to their cost effectiveness over their useful life, rechargeable batteries are often used for the power source of the portable electronic device. Attributes such as “relatively high energy density” and “maintenance free” make Lithium-Ion (Li-Ion) batteries popular in the portable consumer electronic products. Refer to the application note, AN1088, “Selecting the Right Battery System For cost Sensitive Portable Applications While maintaining Excellent Quality” (DS01088) for characteristics of Li-Ion batteries. Some examples of how to properly design with Li-Ion batteries will be discussed in this application note.

Designing A Li-Ion Battery Charger and Load Sharing - [Link]

Don Scansen writes:

For any complete energy-harvesting system designed to provide power to anything but small, short-duration loads, storage batteries represent a necessary but significant portion of the initial expense. The cost of batteries over the lifetime of the system can have an even larger impact if care is not taken to maximize the useful life of the battery component. What’s more, if unit growth continues for photovoltaic and other energy-harvesting systems relying on large-capacity storage batteries, designs that fail to maximize battery life could have a negative environmental impact due to the extra material and energy consumption needed to manufacture replacement systems as well as dispose of exhausted units.

Charge Controller Design for Maximum Battery Lifetime in PV Systems - [Link]

A little known feature of Arduinos and many other AVR chips is the ability to measure the internal 1.1 volt reference. This feature can be exploited to improve the accuracy of the Arduino function – analogRead() when using the default analog reference. It can also be used to measure the Vcc supplied to the AVR chip, which provides a means of monitoring battery voltage without using a precious analog pin to do so.

Secret Arduino Voltmeter – Measure Battery Voltage - [Link]

A Switch Mode Power Supply circuit collection from Linear Technology. It covers 12 basic SMPS circuit categories: Battery, Boost, Buck, Buck-Boost, Flyback, Forward, High Voltage, Multioutput, Off Line, Preregulator, Switched Capacitor and Telecom. [via]

Switching regulator circuit collection - [Link]

Don Scansen writes:

Ambient light, thermal gradients, vibration/motion, or electromagnetic radiation can be harvested to power electronic devices. At the same time, all energy-harvesting-based systems need energy storage for times when the energy cannot be harvested (e.g., at night for solar-powered systems). Rechargeable batteries ‒ known as “secondary” cells to differentiate them from “primary” or single-use cells ‒ are usually specified for this task. This article will examine the various secondary cell technologies available to energy harvesting system designers looking for a cost-effective and powerful battery solution.

Primary and secondary batteries contain the same basic structure of a cathode, an anode, an electrolyte for moving charge between the terminals, and a means to separate them. Secondary cells are distinguished by the type of rechargeable chemistry employed, such as nickel-cadmium or lithium-polymer, or solid-state thin film.

Storage Battery Solutions for Energy Harvesting Applications - [Link]

With the new Accucell Alpha 100 and Alpha 200 chargers you will manage it easily and moreover you don´t have to care about the type of batteries you´ll put in.

RAM batteries (rechargeable alkaline manganese) have already gained many fans, as they are environmentally friendly, have an ideal voltage of cca 1.5V and feature a very low self-discharge. They are mainly suitable for devices with a low to mid power consumption. To maintain their good properties for a long time, it is only necessary to avoid a deep discharge under 0.9V, very high discharging and charging currents and mainly to observe charging characteristics with a current limitation and a maximum voltage of 1.65V/ cell.

New microprocessor controlled chargers Alpha 100 and Alpha 200 control every channel separately, that´s why it is possible to charge any number of batteries from 1 to 4 pcs. They are designed to observe an optimum course of charging for RAM accumulators. This is also reflected in the charging current of 155-195mA x4 (AA) and 70-100mA x4 (AAA) respectively. Charging of common RAM cells lasts approx. 2-12 hours, depending on their capacity and a level of discharge.

New chargers provide one extra bonus – they are also able to charge NiMH and NiCd cells, because they are able to recognize the type (chemistry) of an inserted battery (from a voltage curve at charging), adapting a charging course accordingly.

Charge the environmentally friendly RAM batteries - [Link]

An MSP430-based USB Li-Ion battery charger with a fuel gauge: [via]

The example cases discussed in this application report provide a basic understanding of what needs to be done at production, as well as on the application level, to achieve the aforementioned goals. The associated software provides library functions to interface and communicate with the bq27410 fuel gauge, applicable to any USB-equipped MSP430 device. The software also includes a demo application that integrates the USB stacks and the fuel gauge library functions to read the battery information from the fuel gauge and transmit it to the PC through USB Communications Device Class (CDC).

MSP430 based USB Li-Ion battery charger with fuel gauge - [Link]

SolarCharge 200ds230 rev 2 - An unconventional, scalable high efficiency 12V solar power system, a battery charge controller with low voltage cutout to protect the battery. [via]

An unconventional, scalable high efficiency 12V solar power system and battery charge controller with low voltage cutout to protect the battery. (ideal for systems of 50W or less).

The most common solar charger consists of a Schottky diode to prevent the battery from draining into the PV panel and a shunt regulator that effectively short circuits the panel once the battery is fully charged.
One problem with this approach is diode losses and the resulting heat. If a 50W 12V panel supplies 4A to the battery, the Schottky diode will drop about 0,4V across it dissipating about 1,6W of heat. This requires a heat sink and loses power to heat. The problem is that there is no way of reducing the volt drop, paralleling diodes may share current, but the 0,4V will still be there. The circuit uses a MOSFET in stead of the usual diode and the primary power loss is resistive.

Scalable 12V solar power system and battery charge controller - [Link]

Alexander Weber over at Tinkerlog.com shares his work 3D printing a battery adapter for a Canon Powershot SX200. [via]

Last year I bought a Canon PowerShot SX200 on ebay. I wanted to play a bit with CHDK, the Canon Hack Development Kit to make some timelapse things. Problem was, the battery would hold only up for 2 hours or so. Even worse, the camera has no power jack to attach a power supply. The solution is to buy a battery dummy that has a jack on its back. That costs like 30 euros!

3D Printed Battery Adapter for a Canon Powershot SX200 - [Link]