I'm a 30-plus-year veteran of electrical engineering with experience that spans many areas, including digital, analog, power, communications, and microcontrollers. I work for a company called MaxVision, which makes extreme-performance, ruggedized, transportable workstations. By some strange quirk of fate, Max Maxfield the (world's go-to techno guy) has his office in the same building as mine. Over the years, he has had to tolerate my very bad punny humor attempts over the coffee table, since we share a kitchen in our building.
One day, while I was contemplating a new joke to inflict upon everyone, I overheard a conversation between Max and our mechanical design expert, Eugene "Willie" Richards, about what type of batteries would be the best option for Max's robot project. Since I have considerable knowledge about batteries (robots too), and I was feeling some remorse about my previous puns, I held off on the jokes and offered my assistance.
Max said it would be useful to a lot of readers if I wrote a series of columns on batteries -- beginning with types, technologies, terminologies, specifications, and environment. Later we will cover specific types of batteries in more detail, considering most everything required to understand and select the appropriate technology for a particular application. Once we've considered everything in excruciating detail, we will be in a position to advise Max about the optimal battery technology for his robot.
The battery was invented by Alessandro Volta of Italy in 1800. I'm sure Volta would be amazed by how ubiquitous (and varied) his invention has become. Having said this, for some tasks, it might be more appropriate to select a capacitor, rather than a battery. Surprised? Well, you might at least consider using a capacitor whenever it is assured to have a regular, high-surge-capable supply of electricity. In some cases involving very light loads, it might even be possible to ignore the regular power application -- just charge a super-capacitor once, and it will survive all the way until discarded. Once we have discussed battery terminologies and technologies, the capacitor versus battery choice will hopefully become clear.
There are lots of factors to consider when choosing the battery technology for a particular application. In addition to relative size, weight, and cost (from cheap to expensive to "if you have to ask, you can't afford it"), the main considerations and factors I plan on covering in this series are as follows:
Environment (operating and storage): Temperature, air pressure, altitude, mechanical strain, vibration, mounting position, radiation hardening, corrosive attack, packaging/shape, storage or shelf life, disposal, waste products produced and outgassing, consumables required, safety, and materials/RoHS
Application: Types (including primary, secondary, and smart), technology, chemistries, efficiency and loss, charge/discharge cycle count and rates, depth of discharge, service life, memory effect, charging techniques, capacitor/battery hybrid, use cases, capacity, density (energy and weight), protection circuitry, measuring and gas gauge, quality, reliability, and recharge and run times
Since Volta's first crude models, many types of batteries have come into use. Some of these technologies are as follows.
Nickel metal hydride
Zinc-manganese dioxide (alkaline)
Lithium thionyl chloride
Lithium poly carbon monofluoride
Lithium sulfur dioxide
Lithium aluminium chloride
Lithium cobalt oxide
Lithium iron phosphate
Lithium manganese oxide
Lithium nickel manganese cobalt oxide
Lithium nickel cobalt aluminum oxide
Nuclear or atomic
I won't be able to cover all these technologies in depth -- just some of the more common and/or noteworthy ones. Please add a comment below if you think I've omitted some important technology or if you're interested in a particular one. If you need more information right now, you may find quick, specific answers to your battery-related questions at the
Battery University website.
In my next column I'll cover classifications, general specifications, and terminology. Until then, please post any questions or comments below.
Pulse charging, became popular after Nickel Cadmium came out, to measure the internal resistance. It did something like what you describe, but also had the advantage to help break loose (spoken loosely) materials from the electrodes (or in the case of NiCd to help prevent the formation of micro-fine shorts).
@eetcowie: "Also, Nickel Cadmium types were notorious for growing metal-fiber 'wires', that would partially short out a cell. There appeared a capacitor-based rejuvenator that would pulse a high-current into the cell to blow out the metal fibers and breathe new life."
Back in the mid-to-late 70s Popular Electronics had a simple circuit for a NiCd zapper. It had a 24V transformer and a full-wave bridge that charged a capacitor, and it had a selector switch (charge or zap), a pushbutton to zap, and a meter to monitor the charge on the cap and on the battery. A friend built one to try to resurrect some surplus NiCds he'd bought. One let out a tremendous FLASH and a ZAP, and then started to take a charge. The article said if it didn't start taking a charge after 2 or 3 zaps it never would. He was able to recover most of the "dead" batteries. Not much of a special waveform, but at the cost of used batteries, you didn't lose much by trying. I doubt that would work for Li cells!
I also read that another failure mode with NiCds was that a weak cell caught in a string of good cells would be charged in reverse.
Keep in mind a Pb-based battery needs to be kept fully charged or it dies, so it is derated to allow for capacity loss over the expected life of a battery. And in some countries you need to crank at very low temperature where you have only say 25% capacity available. In temperate climates you can get away with a much smaller battery, especially when you consider you do not have to keep the battery fully charged. It is commonly stated you need only half the capacity of a Pb-based battery. Shipping of Li is an issue, however if each cell is less than 20Wh then it is not that hard.
Join our online Radio Show on Friday 11th July starting at 2:00pm Eastern, when EETimes editor of all things fun and interesting, Max Maxfield, and embedded systems expert, Jack Ganssle, will debate as to just what is, and is not, and embedded system.