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]
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]
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]
Measuring Battery Capacity with an Arduino. Dennis writes- – [via]
I needed a couple of AA batteries and found the display at the supermarket where they were all arrayed. Normally when I’m shopping in the supermarket, I tend to look at the price/kg or price/l when comparing similar products. In the case of the batteries, there was no such indicator. Fine, I thought, I’ll work it out myself. I grabbed a few different makes and scanned the packaging for some measure of their capacity. Nothing. Not a single one of the batteries had any indicator of how much energy they would provide. Instead, they all had terms like ‘PLUS’, ‘SUPER’, ‘ULTRA’ and of course had wildly differing prices. So, I decided that it was time for an experiment and bought one pack of every type I could find.
Measuring Battery Capacity with an Arduino - [Link]
Sam Byford writes:
NEC has been developing its organic radical battery (ORB) technology for a while, and today it unveiled the latest iteration. The newest ORB is a 0.3mm (0.012 inch) flexible battery that’s designed to fit into integrated circuit (IC) cards, commonly used for public transport payment, credit cards, and suchlike. Standard IC cards are 0.73mm thick, meaning the addition of a battery shouldn’t prove too taxing on your wallet. Furthermore, the battery can be printed directly onto the IC card as part of the manufacturing process, and the surrounding 0.05mm polymer film can incorporate circuit boards with small components like antennas.
0.3mm thin ‘organic radical battery’ can be printed - [Link]
This is a very simple capacity tester. It consists of single resistor that discharges battery. Arduino measures the voltage drop across resistor. According to Ohm’s Law current = voltage/resistance. Every second value of current is divided by 3600 and summed up to get the capacity expressed in Ah (Amp per hour).
I have used two parallel connected resistors that total resistance is 6.9 ohm. Make sure that they have proper power rating, if you don’t want them to convert to smoke. If voltage across 6.9 ohm resistor is 3.7 V, then current – 0.54 A, power ~ 2W.
Arduino Lithium-ion battery capacity tester/discharge monitor - [Link]