The circuit uses both op-amps of an LM358 to control the charging of a single cell lithium ion battery. Charging automatically stops when the battery is full, and it is possible to charge batteries that have gone below the undervoltage limit. Power is provided through USB or any other 5V source.
Simple USB DIY Li-ion battery charger - [Link]
If you design circuits powered by CR2032 batteries here’s an article located by Joe Desbonnet which you should consider: [via]
This is an interesting article on how the performance of a cell/battery under pulsed loads can vary dramatically depending on period, peak current, duty cycle and other factors. The article discusses the performance of a CR2032 button cell driving low power wireless protocols such as ANT+ and Bluetooth v4.0.
The impact of high pulse drain on CR2032 coin-cell battery capacity - [Link]
The Texas Instruments bq28550 battery gas gauge provides current and voltage protection, and secure, SHA-1/HMAC authentication for single-cell Li-Ion battery packs. Designed for battery-pack integration, the bq28550 requires host microcontroller firmware support for implementation. A system processor communicates with the bq28550 using one of the serial interface configurations to obtain remaining battery capacity, system run-time predictions, and other critical battery information.
The bq28550 uses an accurate gas gauging algorithm to report the status of the cell. The gauge provides information such as state-of-charge (%), run-time to empty (min.), charge-time to full (min.), battery voltage (V), and pack temperature (°C).
Single Cell Li-Ion Battery Gas Gauge and Protection - [Link]
The design is based around the MCP1640 IC. It is a 350mA 500Khz boost converter with an integrated switch. Due to it’s design the device requires very few external components to function. One Inductor, two capacitors, and two resistors are all that is needed.
The efficiency ranges from 60% to 90% depending on the load and input voltage.
Single battery boost converter - [Link]
New technology improves both energy capacity and charge rate in rechargeable batteries.
EVANSTON, Ill. — Imagine a cellphone battery that stayed charged for more than a week and recharged in just 15 minutes. That dream battery could be closer to reality thanks to Northwestern University research.
A team of engineers has created an electrode for lithium-ion batteries — rechargeable batteries such as those found in cellphones and iPods — that allows the batteries to hold a charge up to 10 times greater than current technology. Batteries with the new electrode also can charge 10 times faster than current batteries.
The researchers combined two chemical engineering approaches to address two major battery limitations — energy capacity and charge rate — in one fell swoop. In addition to better batteries for cellphones and iPods, the technology could pave the way for more efficient, smaller batteries for electric cars.
The technology could be seen in the marketplace in the next three to five years, the researchers said.
A paper describing the research is published by the journal Advanced Energy Materials.
“We have found a way to extend a new lithium-ion battery’s charge life by 10 times,” said Harold H. Kung, lead author of the paper. “Even after 150 charges, which would be one year or more of operation, the battery is still five times more effective than lithium-ion batteries on the market today.”
New technology improves both energy capacity and charge rate in rechargeable batteries - [Link]
Lithium-polymer battery charger chips @ Dangerous Prototypes – [via]
Lithium-polymer batteries are an excellent choice for portable projects. They are relatively cheap, hold a significant charge, and last for a long time. The drawback with these batteries is that they require rather complicated charging protocols. You have to watch out for overcharging, undercharging, overheating, etc…
We are looking for a standard part to use in our projects, so we decided to do a roundup of open source lithium polymer chargers from SparkFun, Seeed Studio, and Adafruit. With the exception of Seeed, all the chargers are based on Microchip’s MCP738xx family of battery management ICs that come in SSOP and DFN packages. They handle all the charging algorithms and usually only require a single external capacitor.
Lithium-polymer battery charger chips - [Link]
Freescale Semiconductor introduced the MM912J637 intelligent battery sensor (IBS), which accurately measures the voltage, current and temperature of lead-acid batteries and calculates the battery state, all while operating in harsh automotive conditions. The ability to accurately assess these battery parameters is becoming more important with increases in the number of hybrid vehicles on the road and overall electronic content in vehicles, as well as the introduction of start-stop systems. [via]
Freescale introduces intelligent sensor for car battery monitoring - [Link]
This is a bar-graph voltmeter for a 12V battery based on the well known LM3914 IC.
I have a 12V car battery attached to a regular 500VA UPS and, because the UPS is old and doesn’t have any management options, this is how I measure the amount of charge in the battery.
It was developed mainly because it gives a nice look to the UPS, with its red, yellow and green leds. It is also easier to read than conventional digital or analog voltmeters.
LM3914 Battery Monitor - [Link]
NiMH cells are gaining wide popularity in, amongst other places, digital cameras. The energy density in NiMH cells may be lower than that of lithium ion cells, but the fact that they are, in most equipment, interchangeable with disposable dry cells makes them very attractive power sources. The similar electrical and mechanical considerations of NiMH and to dry cells, translates into a wide supply of relatively low cost cells. Also, in case of an emergency, you can always revert back to dry cells if all your NiMH cells are discharged. NiMH should under ideal charging conditions charge for 14 hours at 10% of their rated hourly capacity.
A CPU based NiMH charger - [Link]
Over 110 years ago, the legendary inventor Thomas Edison was granted a patent for the nickel-zinc (NiZn) battery, but a multitude of technical problems blocked the commercial success of this type of battery, and it vanished into distant memory. However, the situation started to change around 2000, when nickel-zinc battery technology again became a focus of intensive research due certain advantages over nickel-cadmium (NiCd) and nickel metal hydride (NiMH) batteries – in particular a higher cell voltage, which simplifies the use of primary batteries as direct power sources. The EU is also campaigning to prohibit the use of NiCd batteries due to their cadmium content. The first generation of NiZn rechargeable batteries is now available in AAA and AA formats from suppliers such as Conrad and Volkner (in Germany). [via]
Nickel-zinc batteries get a new lease on life - [Link]