Chip McClelland @ hackster.io published his solar li-po battery charger based on MCP73871 to manage the solar and DC charging of the LiPo battery, TPS63020 Buck-Boost Converter and Maxim 74043 LiPo Fuel Gauge. He writes:
I build connected sensor which are often deployed in local parks where there is no access to utility power. Over the past couple years, I have been refining and testing my solar power modules and have arrived at this compact integrated design. I have a number of these deployed and they have been in continuous service for up to two years. I wanted to share this design in case it might be helpful for your projects. I would also greatly appreciate any input or suggestions on this design so v3 will be even better.
The MAX17055 single-cell fuel gauge from Maxim not only eliminates battery characterization, but also keeps SOC (state-of-charge) error to within 1% in most scenarios. With its ModelGauge m5 EZ algorithm, the device provides tolerance against battery diversity for most lithium batteries and applications. It also allows system designer’s to decide when to shut down the device when the battery gets low, maximizing device runtime.
As the battery approaches the critical region near empty, the ModelGauge m5 algorithm invokes a special error correction mechanism that eliminates any error. In addition, it provides three methods for reporting the age of the battery: reduction in capacity, increase in battery resistance, and cycle odometer.
Fuel gauge needs no battery characterization – [Link]
Fritz Weld @ edn.com proposes a simple circuit to check li-ion battery health. He writes:
Lithium-ion batteries are sensitive to bad treatment. Fire, explosions, and other hazardous condition may occur when you charge the cell below the margin that the manufacturer defines. Modern battery chargers can manage the hazardous conditions and deny operation when illegal situations occur. This fact doesn’t mean, however, that all cells are bad. In most cases, you can replace the discharged battery and increase your device’s lifetime. Figure 1 shows the circuit for testing battery packs.
Simple circuit indicates health of lithium-ion batteries – [Link]
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.
Harvard University researchers have developed a low-cost flow battery that stores energy in organic molecules dissolved in neutral pH water. In their report (see below) they claim that the new battery can run for a decade or more without maintenance.
Flow battery can run for 10 years with zero maintenance – [Link]
This circuit can produce an output of 3.3V and 1A current continuously for a voltage input varying from 2.5V to 4.2V. The LTC3441 is a high efficient buck boost converter which plays a vital role in portable instrumentation because of its fixed frequency operation. This circuit produces the output from a single Li-ion battery. Multiple cells can also be used within the specified range of input voltage.
Input(V): 2.5V DC to 4.2V DC
Output(V): 3.3V DC
Output load: 1A
2.5V-4.2V input to 3.3V output – 1A Buck Boost Converter using LTC3441 – [Link]
Brian Dipert discuss his experience replacing an iphone battery @ edn.com:
About a week ago, in preparing to run some errands, I plugged my iPhone 4S into the charger in my car so that I could stream Pandora while I drove. Oddly, a “this accessory may not be supported” message appeared on-screen; when I unplugged and re-plugged the iPhone to the charger, it didn’t reappear, so I didn’t think anything more of it … until a half hour later, when the iPhone again alerted me, this time with a “low battery” message.
Battery technologies of all chemistry are experiencing revolutionary changes nowadays. Nanotechnology is leading this revolution by yielding new battery technologies including but not limited to Tiny Supercapacitors and Li-ion batteries that never explode at any condition. But, it’s bothersome to make different chargers for different types of batteries. So, Microchip solved this problem by introducing a new hybrid PWM controller, MCP19124/5, that charges batteries of any chemistry.
The power of this charging device lies in the combination of an 8-bit PIC microcontroller and an analog PWM controller in one package. This mixed signal low-side PWM controller features individual analog PWM control loops for both current regulation and voltage regulation. It can be configured with separate feedback networks and reference voltages. Any voltage, current, temperature, or duration can be used to trigger a transition to a different charging profile.
Various types of batteries require different charging profile. So, the only way to charge all kinds of batteries with a single device is to simulate all the charging profiles. A user can set his/her desired profile with the help of two independent current and voltage control loops, along with variable reference voltage. Now let’s get to know more details about this versatile PWM controller IC.
The MCP19124/5 is a mid-voltage (4.5-42V) analog-based PWM controller with an integrated 8-bit PIC Microcontroller. There are two devices, the MCP19124 and MCP19125, where the last one has four I/O pins more than the first one. MPC19124 and MPC19125 are packaged in 24-lead QFN package and 28-lead QFN package respectively. It has following features:
Smooth, dynamic transitions from constant-current to constant-voltage operation
Dynamically adjustable output current and output voltage over a wide operating range
Wide operating voltage range: 4.5-42V
Analog peak-current mode Pulse-Width Modulation (PWM) control
Available fixed frequency (31 kHz to 2 MHz)
I2C communication interface
9 GPIO for MCP 19124 and 12 GPIO for MCP19125
Integrated high voltage linear regulator, with external output
Integrated temperatures sense diode
Integrated 10 bit A/D converter
Minimal external components needed
Custom algorithm support
Topologies supported include Boost, SEPIC, Flyback, and Cuk
In fact, the above list is just a brief overview. The controller is so complicated that user must read all 236 pages of the datasheet to gain sufficient knowledge.
Now, the question is, how can we use this IC to design an efficient battery charger?
To find the answer, one must read the datasheet thoroughly. At the same time, in-depth knowledge about the target battery is also required. However, Microchip provided a few schematics (as references) in the datasheet based on different applications. The circuit on battery charger is given below:
This ultimate powerful dual-loop PWM controller is going to be a game changer and part of the battery technology revolution. It possesses lots of possibilities. To learn more about this fantastic hybrid controller, study the datasheet carefully.
Battery anxiety is a modern day problem for many of us. Mobile phone and wearable technologies are getting developed rapidly, but battery issues seem to be neverending. As phones and wearables are getting thinner, there needs to be a trade-off between battery life and design. Scientists are searching for a way to make a battery that’s tiny yet capable of holding the charge for a long time. So, what’s the solution? Supercapacitor.
Scientists have been researching on the use of nanomaterials to improve supercapacitors that could enhance or even replace batteries in electronic devices. But it’s not an easy task. Considering a typical supercapacitor, it must be a large one to store as much energy as a Li-ion battery holds.
To tackle the battery issue, a team of scientists at the University of Central Florida (UCF) has created a tiny supercapacitor battery applying newly discovered two-dimensional materials with only a few atoms thick layer. Surprisingly, the new process created at UCF yields a supercapacitor that doesn’t degrade even after it’s been recharged/discharged 30,000 times. Where a lithium-ion battery can be recharged less than 1,500 times without significant failure.
So, what else makes the supercapacitor special apart from their tiny size? Well, let’s hear it from Nitin Choudhary, a postdoctoral associate who conducted much of the research :
If they were to replace the batteries with these supercapacitors, you could charge your mobile phone in a few seconds and you wouldn’t need to charge it again for over a week.
Supercapacitors are not used in mobile devices for their large size. But the team at UCF has developed supercapacitors composed of millions of nanometer-thick wires coated with shells of two-dimensional materials. A highly conductive core helps fast electron transfer for fast charging and discharging. And uniformly coated shells of two-dimensional (2D) materials produce high energy and power densities.
Scientists already knew 2D materials held great promise for energy storage purpose. But until the UCF developed the process for integrating those materials, it was not possible to realize that potential. Nitin Choudhary said,
For small electronic devices, our materials are surpassing the conventional ones worldwide in terms of energy density, power density, and cyclic stability.
Supercapacitors that use the new materials could be used in phones, wearables, other electronic gadgets, and electric vehicles. Though it’s not ready for commercialization yet. But the research team at UCF hopes this technology will soon end the battery problem of smartphones and other devices. So let’s wait awhile, and at the end of this year maybe you’ll be using a new smartphone that can be charged in seconds and lasts for a week, who knows!
Lithium-ion batteries are very popular as they’re lightweight and have high energy density. But at the same time, li-ion batteries are very sensitive to overcharge/over discharge. An internal short circuit can cause fire and it may even lead to a violent explosion. Fortunately, nanotechnology found a way to prevent this kind of nightmare. How? let’s discuss:
Why Does li-ion Battery Explode?
When a device draws too much power from a Li-Ion battery, it heats up and thus melts the internal separator between the two flammable electrolytes. This phenomenon ignites a chemical reaction between the electrolytes causing them to explode. Once their package ruptures, the oxygen in the surrounding air helps the flammable electrolytes to catch fire. The fire then spreads quickly to other cells and loads a thermal runaway.
During a thermal runaway, the high heat of the damaged or malfunctioning cell can propagate to the next cell, causing it to become completely thermally unstable as well. In some worse cases, a chain reaction occurs in which each cell disintegrates at its own timetable.
So, in a nutshell, Li-ion cells possess the potential of a thermal runaway. The temperature quickly rises to the melting point of the metallic lithium and cause a violent reaction, which finally causes an explosion.
How Can Nanotechnology Prevent This?
Recently conducted research shows that atomic layer deposition (ALD) of titania (TiO2) and alumina (Al2O3) on Ni-rich FCG NMC and NCA active material particles could substantially improve Li-ion battery’s performance and allow for increased upper cutoff voltage (UCV) during charging, which delivers significantly increased specific energy utilization.
A company called Forge Nano claims to prevent this thermal runaway situation by never letting it get started even if the battery electrodes are shorted out. Forge Nano’s precision coatings on cathode and anode powders protect against the most common degradation mechanisms found in Li-ion batteries.
The benefits of Forge Nano precision coatings include extended battery life and greater safety, especially in extreme situations such as high-temperature operation, fast cycling rates, and overvoltage conditions.
By implementing lithium-based ALD films in nanostructured 3D lithium-ion batteries, significant gains in power density, cycling performances during charge/discharge, and safety is noticed.
What’s the Result?
Some of Forge Nano’s accomplishments in the Li-ion battery space includes:
Increased lifetime of commercial cathode material by as much as 250%
15% higher energy density in large format pouch cells (40 Ah) that pass nail penetration testing
60% reduced gas generation in cathode material
A low-cost high-voltage cathode powder with exceptional performance
Increased rate capability of conventional materials for enhanced fast charge acceptance using Forge Nano’s proprietary solid electrolyte coatings
Since the solution found by the research, Forge Nano has been working on a commercial version of the product that they finally believe they can place in the market very soon.