Thermal runaway has never been far from the minds of design engineers who use lithium-ion batteries, especially since the first reports of laptop fires surfaced more than a decade ago.
Electronics suppliers are helping engineers prevent such problems with the introduction of new battery management integrated circuits that monitor voltage, temperature, and current conditions at the battery.
"The main condition is overvoltage," says Yevgen Barsukov, IP development manager for battery management systems at Texas Instruments. "Normal voltage for a lithium-ion battery is 4.2V. If the battery is charged to 4.3V or 4.4V, it can take you to a condition where you have thermal runaway."
TI's bq275xx family of battery management ICs provides protection for battery packages. The ICs, which measure just a couple of millimeters on a side, include a microcontroller, flash memory, random access memory, and an analog-to-digital converter. The devices serve as gauges for handheld devices such as cell phones, laptops, and tablets.
Both TI and Analog Devices make management units for electric vehicle batteries. In June, TI unveiled bq76PL536, a battery management unit targeted at rechargeable lithium-ion packs for EVs, hybrid vehicles, and power tools. Last year, Analog Devices rolled out the AD8280, which works with a series of high-voltage comparators to "look" for undesirable voltage or temperature conditions in vehicle battery packs.
"The idea is to monitor for voltage, temperature, and overcurrent conditions," Barsukov says. "If any of the conditions are exceeded, the battery management system will turn off the appropriate components."
One clearly gets a sense, from all the stories recently on batteries, that portable power sources have become a gating factor for many of the things we'd otherwise be able to do easily. I'm not just talking about electric vehicles, where batteries are clearly THE gating factor. This applies to all manner of miniaturized electronics, as well as systems situated in hard to get at places (where it's difficult to recharge). Rising alongside all the work on batteries, we're seeing a ramp in energy capture technologies. I guess it's all part of the alternative energy arena. Hey, can I call it alt.eng?
Batteries are definitely the talk of the town given people's love affair with all-things electronics. Put this one in the out-there bucket: I just read about a Stanford University research team which invented a totally transparent lithium-ion battery because they want Apple to invent a see-through iPhone. Who knew?
As an electrical engineer (retired) and a casual flier of electric model airplanes, I have closely watched the development of Lithium Ion battery sources for models over the last 10 to 15 years. Lithium Ion batteries have finally made the dream of electric powered model airplane flight possible and, today, many of those in the hobby have switched over totally (I know that I have - no more glow fuel for me!).
Of course, there were some problems and the fire issue was (and still is) a very serious concern. The risk has been mitigated to some extent with better chargers, improved battery construction, smarter control devices between the battery and the motor(s), the use of different battery materials and a strong education campaign by the model industry.
There is still a ways to go and providing 'smart' batteries with more integrated control and safety circuits might be the way to proceed for the model industry. The downside is, of course, the cost increase for the battery pack and a question of standarization.
Overall an interesting marketing and engineering problem in a rapidly evolving field.
Yes, long overdue - Power management for Lithium Ion batteries, that is. My laptops, some brand new, in 'Stand-By' mode sometimes get so hot I can barely touch the back of the unit.
So the laptop is apparently converting stored energy from the battery into Heat!
I have to wonder, what the heck is this computer doing or attempting to do, that is so important, to generate all this heat, when I just told it to go into Standby...
So yes, these new chips and these new designs are welcome improvements...
A new book by Thomas Edison's great-grandniece takes on the notion that he was a lone-wolf inventor and replaces it with an image of a man who ascribed great value to the ideas of colleagues.
In response to rising interest in autonomous vehicles, the federal government has called upon states not to authorize operation of self-driving cars, except for the purpose of testing.
With LEDs dropping in price virtually every year, automakers have begun employing them, not only on luxury vehicles, but on entry-level models, as well.
Using almost 200 light-emitting diodes in the front and back of the new 2014 CTS, Cadillac designers are showing how LEDs can change the character of a vehicle.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 5
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For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This radio show will show what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.
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