Electronics-Lab.com Blog

The LT3651 enables fast charging of Li-Ion/Polymer batteries by delivering up to 4A of continuous charge current with minimal power loss. This is due to its high efficiency switchmode topology, including on-chip synchronous MOSFETs. Its autonomous operation means no microcontroller is necessary and the device integrates an onboard C/10 or timer charge termination. The LT3651’s programmable input current limit with PowerPathTM control regulates charge current to maintain a constant supply current, preventing the input supply from collapsing.

• Wide Input Voltage Range: Up to 32V (40V Absolute Maximum)
• Programmable Charge Current Up to 4A
• Selectable C/10 or Onboard Timer Termination
• Dynamic Charge Rate Programming/Soft-Start
• Programmable Input Current Limit

LT3651 – Monolithic 4A High Voltage 1 Cell Li-Ion Battery Charger - [Link]

State-of-Charge Measurement for Lithium-Ion Batteries is an advanced task, but can be simplified using specific ICs able to measure accurate SOC of Li-Ion batteries. Stephen Evanczuk writes:

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.

For rechargeable batteries, however, battery management depends on the best possible measurement of what is known as the state-of-charge (SOC) of battery cells. For lithium-ion batteries, the characteristics of Li-ion cells complicate SOC measurement and can challenge engineers looking to maximize Li-ion battery lifetime. To simplify design of Li-ion battery management systems, engineers can leverage a variety of SOC measurement techniques supported in ICs from Atmel, Linear Technology, Maxim Integrated Products, STMicroelectronics, and Texas Instruments.

Advanced ICs Simplify Accurate State-of-Charge Measurement for Lithium-Ion Batteries - [Link]

mic @ wemakethings.net writes:

For a long time I wanted to enter the 21st century by stopping using NiCad or NiMH batteries and upgrading to Lithium accumulators as they provide more power per volume and are cool in general. Constant flow of obsolete cell phones provides a nice source of reasonably high-performance batteries for free – I felt compelled to tap into this resource for my battery operated projects.

Open source Lithium battery charger modules - [Link]

The LT®3651-8.2/LT3651-8.4 are 2-cell, 4A Li-Ion/Polymer battery chargers that operate over a 9V to 32V input voltage range. An efficient monolithic average current mode synchronous switching regulator provides constant current, constant voltage charging with programmable maximum charge current. A charging cycle starts with battery insertion or when the battery voltage drops 2.5% below the float voltage. Charger termination is selectable as either charge current or internal safety timer timeout. Charge current termination occurs when the charge current falls to one-tenth the programmed maximum current (C/10). Timer based termination is typically set to three hours and is user programmable (charging continues below C/10 until timeout).

LT3651-8.2 and 8.4 – Monolithic 4A High Voltage 2-Cell Li-Ion Battery Charger – [Link]

Bryon Moyer writes:

The development of wireless sensing technology has made possible tasks that would have been unthinkable in years past. Sensors can be installed where it is impractical or impossible to run a communication wire; their ability to communicate wirelessly, as long as they are within range of a hub, means that it is possible to gather data in places or situations that were previously inaccessible.

The inability to run a communication wire to the sensor also means no power line as well. Sensors need power both to sense and to communicate, so that has typically meant using a primary battery. While you would presumably select a battery with as long a life as possible, the battery is still unlikely to outlast the life of the sensor, meaning that someone will have to go out and replace the battery at some point – which can be expensive.

Managing the Energy and Lifetimes of Thin-Film Batteries - [Link]

Stephen Evanczuk writes:

Lithium-ion batteries have emerged as a common energy-storage device in many energy-harvesting applications. For engineers, maximizing battery performance and lifecycle requires use of battery charging circuitry able to account for the specialized characteristics of Li-ion cells. Engineers can cost-effectively build in Li-ion-charging functionality using available ICs from manufacturers including Analog Devices, Diodes Inc., Fairchild Semiconductor, Fujitsu Semiconductor, Intersil, Linear Technology, Maxim Integrated, Micrel, Microchip Technology, and Texas Instruments.

Unlike many other battery technologies, Li-ion cells require a charging profile maintained within a tight envelope. An undercharged Li-ion battery simply cannot provide its full rated energy output. On the other hand, charging circuits cannot afford to push Li-ion battery voltage above recommended limits or apply charging currents that exceed manufacturer-recommended levels. In either case, application of overvoltage or excessive charging current begins to break down Li-ion cells, reducing overall battery life or even resulting in catastrophic failures. For engineers, the challenge is maximizing charging rate and cell voltage without overcharging the cells.

Constant-Voltage/Constant-Current Devices Optimize Li-Ion Battery Charging for Energy-Harvesting - [Link]

circuitsdiy.com writes:

This is a simple li-ion charger without a dedicated li-ion charger IC. This circuit can be used to efficiently and intelligently charge any single cell Li-ion battery pack like mobile battery, digicam battery, etc.

Features:

• Charging via mini-USB connector which is very common.
• Charging status display by LED
• Simple circuit by using opamp, resistor, and not by any complex dedicated IC or micro-controller.
• Charges completely drained (0V) battery packs.
• Max charging current 500mA (limited by USB supply), depending on battery.

Simple USB DIY Li-ion battery charger - [Link]

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]

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]