Ultracapacitors Soon to Replace Many Batteries? 415
einhverfr writes "According to an article in the IEEE Spectrun, the synergy between batteries and capacitors — two of the sturdiest and oldest components of electrical engineering — has been growing, to the point where ultracapacitors may soon be almost as indispensable to portable electricity as batteries are now. Some researchers expect to soon create capacitors capable of storing 50% as much energy as a lithium ion battery of the same size. Such capacitors could revolutionize many areas possibly from mobile computing (no worries about battery memory), electricity-powered vehicles, and more."
Re:Myth (Score:5, Informative)
The problem I've had with all of them is their life span. After a year of regular use, they then to hold a fraction of their original charge. It appears ultracapacitors have a much longer life span. rock on
Re:Myth (Score:3, Informative)
Re:obvious (Score:4, Informative)
Re:NiMH are also affected, in a different way. (Score:2, Informative)
Call me back when it's 100% or more (Score:1, Informative)
Any step backward simply cannot be tolerated in regard to power stored.
Until they can provide the same density as a lithium ion battery, their product is essentially useless to the public.
Re:Better tasers? (Score:5, Informative)
The capacitor is charge via the battery, and the charge is released over a shortened interval. Same deal with a camera flash.
The could already make tasers lethal in nearly all cases if they wanted to, but the point of them is that they aren't lethal in most cases.
Re:Could someone explain the jargon? (Score:4, Informative)
Article wrongly disses flywheels (Score:3, Informative)
Re:Call me back when you have some imagination (Score:2, Informative)
even if these caps only hold a charge for 1 hour, they will recharge in a few seconds and will be 5 time lighter then batteries. are you really so dense as to be unable to see applications for a lighter faster charging power source?
Re:Myth (Score:5, Informative)
Re:Do they burst and leak fluid? (Score:2, Informative)
So-called memory effect (Score:3, Informative)
Re:Vaporware (Score:2, Informative)
Re:Do they burst and leak fluid? (Score:5, Informative)
The most common thing you see are electrolytic capacitors, which can indeed burst if they're of extremely poor quality (and cause an environmental hazard along the same lines) -- but of course, saying that is true of many many things. Take paint for instance -- we cover everything in it, and it's generally safe, with only a few exceptions like lead paint, which will make you sick, or the stuff they coated the Hindenberg with, which could also be used as rocket propellant...
Modern electrolytics are much better, although their operating characteristics aren't the greatest -- they have a high capacity, and that's about it.... they're not at all reliable or tolerant of varying operating conditions. Fortunately, many applications don't require this...
You can use all sorts of other things inside a capacitor: paper, glass, ceramic and kevlar are used to name a few, or you can forego the dielectric completely, and put a vacuum between the two plates.
Oh, and supercapacitors don't use electrolyte as the dielectric. That's not to say they won't go boom -- I have no idea how they operate, but they're not filled with the same stuff as what you're thinking of -- if they were, they'd still just be plain old unremarkable electrolytic capacitors.
Re:Myth (Score:5, Informative)
Plastic film capacitors will wear out if they are operated at excessive currents.
High-k ceramic capacitors degrade partially over time.
Re:Myth (Score:5, Informative)
Memory is a very specific occurrence in very specific conditions with a very specific type of cell (sintered plane nickel-cadmium). It exists. You've never seen it.
>>I have an 2 year old cell phone that doesn't hold a charge at all and it has a lithium battery.
It's not memory. It's worn out (too many cycles) or reached the end of its calendar life (since manufacturing, not since you bought it - newer-generation LiIon cells are much better at this aspect). Or both. All cells do this eventually. 2-3 years for a consumer grade cell is not at all unusual. Yes, there are exceptions; I own a few of them.
Capacitors have a lifespan of "functionally forever." You're right: perfected, they'll be a whole lot better than any type of cell we have now.
R
mod parent up (Score:4, Informative)
Memory is a very specific occurrence in very specific conditions with a very specific type of cell (sintered plane nickel-cadmium). It exists. You've never seen it.
The above is spot on.
Another common cause of what is incorrectly thought to be "memory" is the corollary myth that you MUST deplete NiCd batteries completely before charging. While a full discharge can, in fact, sometimes be useful for certain types of cells, this is generally untrue for real-world batteries (comprised of multiple cells). A battery with several cells in series will always have slightly unbalanced cells, and the weaker cells will lose charge first. As the weakest cell begins to collapse, its neighbors in the string will crush it to zero volts, and then to a negative (reverse) voltage. To permanently damage a cell more effectively, you'd really have to apply yourself.
ALWAYS stop using the battery at the first sign of depletion -- continuing to use it will just kill one or more of its cells.
Re:Myth (Score:3, Informative)
Battery memory is a specific problem with specific preventative measures and fixes. Would you call a lead acid battery's tendency to sulfate if left uncharged(or deeply discharged) memory? While it does lead to lower capacity and shortened life, it's not the same thing as NiCad memory.
From my understanding, LiIon tech currently degrades with age - it doesn't matter how often the battery is charged*, it's charge state or anything. It's pure degradation over time - it could be sitting in a controlled climate warehouse and it'd still be substantially worse after only a year or three. And it's permanently lost - so I'd hardly call it a memory issue. At least with memory problems you can more or less fix the batteries without reprocessing them.
*though this still wears the battery out.
Re:I doubt it will be viable in notebooks (Score:3, Informative)
Re:Interesting - crashes? (Score:5, Informative)
In terms of dumping current, yeah, the capacitor is very dangerous. That said, the amount of current contained (per device) in the largest supercaps I've seen thus far is not significantly greater than what an automotive-grade lithium ion battery pack can dump in a fraction of a second. The difference is that when you short out the supercap, only the shorting material catches on fire instead of the battery and any combustible materials nearby.
Unlike lithium ion cells, supercapacitors don't spontaneously combust when exposed to oxygen, react badly to conventional fire suppression systems, and release a highly caustic smoke that can cause severe lung damage if you breathe it. They don't burst into flames when overcharged or shorted. They don't get so hot that they can ignite adjacent materials when shorted. And so on.
Not a fan of fans (Score:3, Informative)
Some primitive recharagable Ni-cad/ni-mh battery chargers look for an increase in battery temperature to know when to stop charging.
There is a fine point where a battery stops charging and starts cooking. This is sometimes measured either by temperature or by looking a subtle changes in way the charging current varies over time. Other chargers are more stupid and either always charge or charge for a fixed amount of time.
Li-ion batteries are much more delicate and require more complex rechargers...
Re:Can you? There are other limits. (Score:3, Informative)
The GP mentioned equipment like phones and PDAs, which typically have a battery of about 700 mAh at 3.7 V = 9000 Ws. Household wiring in Europe can usually do 16 amps at 230 V = 3680 W. With a factor 2 for conversion losses and power factor it means you could recharge the battery in 5 seconds or so. The biggest problem is that you need some kind of switched power supply with 10 times more capacity than that in a desktop pc, so that would be a pretty big and expensive battery charger.
Too much faith in humanity? (Score:3, Informative)
So I'll bet someone _will_ take it as necessary proof of manhood to take it apart, cut the cables, and make a dangerous mess, just because, you know, his dad told him that Real Men mess with their car's engine. And if he doesn't take it apart and make a bigger mess (before finally taking it to the mechanic anyway), then he might as well wear a dress and a purse.
2. And that's not even counting the millions of clueless rice boys [riceboypage.com] (car modders) and the unscrupulous vendors preying on them. Someone _will_ sell clueless insecure guys a special power cable claimed to increase their horsepower by 10%, or something equally ridiculous. (Same as the 1000$ hi-fi power cables sold to "audiophiles," or 4" exhaust pipes for 1.1 litre engines. Odin knows there's no shortage of buyers for either.) Watch them take the engine apart and do dangerously irresponsible things with the cables.
Or, honestly, it just begs doing dangerous stuff with the voltage at either the capacitor (to increase range), or the electro-motor (since torque and horsepower do increase with voltage.) When some insecure kid's bragging rights depend on how fast he can accelerate, do you honestly think it won't happen? I can see the whole overclocking willy-waving contest happening all over again with cars.
And as with chips, there'll be a bit of variation to how much you can push a part. The fact that there's always a safety margin doesn't mean it's _guaranteed_ to go X% higher. The safety margin is there precisely because you get a bit of a gauss curve, and some parts will fall a bit short. Some motors will cheerfully take twice the voltage, some will have a spot of thinner wire or insulation and short out. Some capacitors will cheerfully take more voltage, some will have a weaker bit of insulation somewhere between those plates, and get an arc right through it if you push them.
Except with overclocking, at most you fry the chip, and tend to see it crashes long before that. With a capacitor you just get a hell of a lot of energy discharged in a very short time. Assuming that the capacitor only holds the energy of, say, half a tank of gasoline, discharging all that energy in half a second is very much equivalent to half a tank of gasoline blowing up. Better yet, stored energy rises with the square of the voltage, so over-volters will get quite the fireworks.
3. Well, what the blueprints say, and what the whole thing looks like after crashing into a tree, are often different things. I'm sure, for example, in normal cars radiator blueprints don't involve it having several breaks and punctures either.
Re:Interesting - crashes? (Score:4, Informative)
However, in a hybrid, there are usually one or two intermediaries between the wheels, electric motor, and battery storage. The intermediaries are the gearbox and power electronics. Both of these intermediaries convert input power to output power: input torque and shaft speed to output torque and shaft speed, input current and voltage to output current and voltage. The efficiency of the conversion varies depending on design and operating conditions, but is theoretically 100%.
With some intelligence built into the powertrain (i.e., computing power, algorithms, control laws), you can adjust the gearbox setting (by shifting gears) and the power electronics (by modulating frequency or duty cycle) such that braking torque can be constant throughout deceleration. The deceleration power in the mechanical and electrical subsystems won't be a constant, though.
My understanding is that the main reason the Prius has to use its mechanical brakes at all is that the components in the regenerative powertrain have maximum power ratings. For instance, the batteries have some maximum charging current limit. So the computer has to augment the regenerative braking (which is power-limited) with the mechanical brakes (which don't have that limit in normal usage).
This is why having ultra-capacitors in place of or augmenting the batteries will be so useful - they have almost no current limit, and can absorb the spikes for accelerating and decelerating in stride.