Designers of rechargeable battery-powered equipment want a charger that minimizes charge time with maximum charge current by maximizing the power taken from the supply without collapsing the supply. Resistances between the supply and the battery present a challenge. This article explains how to design the charging circuit to achieve the maximum power from the adapter despite the undesired resistances between the supply and battery.
AppNote: Extract maximum power from the supply when charging a battery - [Link]
Organic LED, microprocessor controlled, intelligent energy source for all of your electronic devices.
Legion is a portable energy source with a built-in Organic LED display coupled with a microprocessor. It can charge any USB powered electronic devices. Unlike a traditional portable battery where you’re left in the dark about the state of charge of your battery, Legion learns how you use your electronic devices and displays precisely how much more time (day:hours:minutes) you have remaining until you run out of power. Legion uses premium grade Lithium Polymer batteries designed to maximize your energy density while packing it into the smallest area possible. Legion is proudly designed in Silicon Valley, California.
LeGion Halves Phone Charge Times – [Link]
Fully Programmable Solar BMS ( Battery Management System ) Learn to program microcontrollers and HW design video tutorials Open Source:
This Battery Management System development board is designed to work with any type of rechargeable Lithium batteries and supercapacitors thanks to fully user programmable parameters.
Whenever you need to use a rechargeable lithium battery you will also require a BMS. Most small device have them integrated like the battery from your laptop, cellphone or cordless power tools (if they use Lithium). Same is true for supercapacitors (EDLC).
Open Source Programmable Solar BMS Li-ion, LiFePO4 dev board - [Link]
Embedded legend Jack Ganssle tackles the question of how much juice you can pull from a coin cell. He writes:
About a year ago I wrote of my on-going experiments to determine how coin cells behave. This was motivated by what I consider outrageous claims made by a number of MCU vendors that their processors can run for several decades from a single CR2032 cell. Some vendors take their MCU’s sleep currents and divide those into the battery’s 225 mAh capacity to get these figures. Of course, no battery vendor I’ve found specifies a shelf life longer than a decade (at least one was unable to define “shelf life”) so it’s folly, or worse, to suggest to engineers that their systems can run for far longer than the components they’re based on last.
Conservative design means recognizing that ten years is the max life one can expect from a coin cell. In practice, even that will not be achievable.
There’s also a war raging about which MCUs have the lowest sleep currents. Sleep current is, to a first approximation, irrelevant, as I showed last year.
But how do coin cells really behave in these low-power applications? I’ve been discharging CR2032s with complex loads applied for short periods of time and have acquired millions of data points.
How Much Energy Can You Get From A Coin Cell? - [Link]
Compact battery chargers require overcurrent protection and temperature monitoring to ensure safety. These chargers also need to fit into small form factors, and generally have a lot of pressure to also be very inexpensive, but only have to provide a simple charging ability.
Furthermore, compact packaging is required to integrate the battery charger into a system. Renesas has 8/16-bit microcontrollers available in compact packages with as few as 10 pins, making them ideal for these applications.
78K0/Kx2: 8-bit All Flash microcontroller: wealth of on-chip peripheral functions such as a reset circuit and on-chip oscillator; low power consumption,30 to 80 pins.
78K0/Kx2-L: 8-bit All Flash microcontroller: wealth of on-chip peripheral functions such as a reset circuit, on-chip oscillator, and operational amplifier; ultra-low power consumption, 16 to 48 pins
78K0S/Kx1+: 8-bit All Flash microcontroller: wealth of on-chip peripheral functions such as a reset circuit and on-chip oscillator; 10 to 30 pins
R8C Family: Timer, 5 V operation, and Small Package
P-ch MOSFET: Low on-resistance, compact low-profile
Renesas Battery Charger Solutions - [Link]
The electrolyte is also modified with bio-organic nanodots made from peptide molecules. The new battery technology came about as a result of crossover research into Alzheimer’s disease at Tel Aviv University. The work identified organic peptides (amino acids) which are now being used in StoreDot’s bio-organic battery. The nanodots are made from a range of naturally occurring environmentally-friendly bio-organic raw materials and employ a basic biological mechanism of self-assembly, making them cheap to manufacture.
A conventional micro USB connector would not be able to handle the 180 A necessary for a 30 second recharge of a typical cell phone battery. These sort of charge times would remove a significant hurdle in the development of electric vehicles if the technology is transferable. The design is still at its prototype phase; the developers anticipate the final design of the battery and its charger unit will see a significant reduction in size.
Bio-Battery Recharges in 30 Seconds - [Link]
cpldcpu did a teardown of an external USB battery:
The device has a USB micro-b socket which is used as 5V input for charging, and a normal USB-A socket as 5V output. The output power can be turned off and on by a toggle button. There are LEDs to indicate active power out (blue) and charging (red) states. The pictures above show the innards of the device. Most space is taken up by an ICR18650 LiIon battery, which are relatively common devices with 2600mAH. In addition, there is a tiny tiny PCB. The rear side of the PCB is dominated by a 4.7µH inductor, which is part of the boost converter to convert the 3.7V of the battery to the 5V USB output.
Tear down of a cheap external USB battery - [Link]
Startup company Aquion Energy gave MIT Technology Review a behind-the-scenes look at their battery manufacturing process. The company’s goal is to make non-toxic, cheap batteries for storing off-grid energy. The batteries will first be sold in regions that don’t have access to an electrical grid, such as rural areas and villages in poor countries.
How to Make a Cheap Battery for Storing Solar Power - [Link]
James Wood designed a simple circuit that is able to indicate when the battery of a system is low and needs replacement. He writes:
The Design Idea in Figure 1 indicates a low-battery condition in an audio test instrument that is powered by four AA cells. As the instrument was otherwise an all-discrete design, this same approach seemed more in keeping with the spirit of the project than the use of a single-sourced integrated circuit.
A garden-variety red LED serves as both the indicator and the voltage reference. A small current through R5 forward biases the LED, but its glow at this low value is barely visible, even in a dark room.
Simple circuit indicates a low battery - [Link]
The weak link in electric vehicle technology is the method of energy storage and renewal, making the vehicles impractical for long distance use. The majority of today’s electric vehicles use rechargeable lithium-ion batteries which still have a relatively poor energy density compared to conventional fossil fuels and require lengthy recharge cycles. A promising alternative battery chemistry is the lithium-sulfur battery. It can store as much as four times more energy per mass than lithium-ion batteries.
Unfortunately reactions at the battery’s sulfur-containing cathode form molecules called polysulfides that dissolve into the battery’s electrolyte. The dissolved sulfur eventually develops into a thin film called a solid-state electrolyte interface layer which coats the lithium-containing anode making the battery unusable after only 100 charge/discharge cycles.
Researchers at the US Department of Energy’s Pacific Northwest National Laboratory have succeeded in quadrupling the useful number of charge/discharge cycles. They have developed a graphite shield which moves the sulfur side reactions away from the anode’s lithium surface, preventing it from growing the debilitating interference layer. The new hybrid anode combines graphite from lithium-ion batteries with lithium from conventional lithium-sulfur batteries.
Graphite Boosts Battery Life - [Link]