Engineers Take 2nd Look...
Written by Greg Allen
Tuesday, 13 May 2008
I love it that more engineers are starting to realize the true benefits of ultracapacitors over traditional lead acid and lithium ion batteries. Ultracapacitors are so perfect for many electronic components. Batteries offer great energy storage, but they take a very long time to charge and degrade after a few hundred charge/discharge cycles. Now we have ultracapacitors, where you can store energy quickly and have hundreds of thousands of charge/discharge cycles.
Let’s recap a few significant characteristics of ultracapacitors:
Virtually unlimited life cycle
Low internal resistance compared to a battery
Ability to operate at very low temperatures (-40°C)
High power density due to high discharge current
Low Equivalent Series Resistance (ESR)
Effective capacitance for specific pulse widths
Charge in seconds and no danger of overcharging
A great example of current use of ultra capacitors are in Uninterruptible Power Supply (UPS) systems. Until recently, batteries were the only choice you had. Ultracaps can reduce the size of the UPS system needed as well as the cost. Ultracapacitors also provide instantaneous supply of energy without delay and are being used as a short term power bridge for applications that are using fuel cells.
Below is a great chart that someone sent to me that breaks down the differences of batteries and ultracapacitors...
Most all products and applications have been engineered the traditional way. Times have changed and I think engineers need to take a good look at ultracapacitors as a new alternative. The car industry has taken a 2nd look at ultracapacitors.. now consumer electronics are looking. So.. this is my passion and I am very interested in helping get ultracapacitors into more and more products. It will help make this world greener... one product at a time.
Readers have left 9 comments.
One piece of important data is missing from the chart: density. We see a high power density by weight, and a low but reasonable energy density by weight, but we have no way of knowing numbers by volume. Volume doesn't matter much in UPS devices, but it becomes very important for vehicles.
No.2 Great Point
Good point on the volume. I will see if I can find a chart that represents that as well because it is very important with vehicles. I was thinking and focusing on the UPS solution.
No.3 Ultracapacitors are sexy
I think ultracaps are sexy.
it seem like the duration is too short for ultracap to maintain the output. 30S?
assume that we put few ultracap together so that it will have the same output duration with battery, will the volume and weight outmatch battery?
[kuku], a low discharge time is a good thing. Of course you don't have to discharge that fast - it's the minimum time to discharge. Think of a bottle of water with a wide neck (ultracap) versus one with a very narrow neck (battery).
No.6 Steve, PE
I'd like to the see the volume spec too. However, if you consider the empty space in a car, there's really a lot of space available. No gas engine, how about the volume for the gas tank. An how about adding mere 2" layer the width and length of a car -- that's several cubic feet. Surely a prototype car could be made with this technology.
No.7 so i understand?
a ultracap can discharge in less than 30s if that much power is reqired but if like a cell phone that only need 5v minor amps would last all day? is this correct?
Wow, very interesting read thanks. Agree with above comments re volume, would also be interested in adding Li-Ion to the above and also a comparison of the approximate current costs per equivalent capacity/volume for the different ultracap technologies and battery technologies...
No.9 Practical performance
If you are comparing a UC UPS w/ a conventional UPS, then you could/should give a more practical comparison of the performance. Yes, a UC doesn't HAVE to discharge that fast, but if in practical use it still DOES discharge that fast, then where's the benefit?
If you're saying that w/ a LA battery UPS, I can get 20 minutes (.3 hr) to 3 hours to do critical work w/ my computer, but I only get 30 seconds to shut it down w/ a UC, then I'm cooked. If, instead, you are saying that a UC will give similar performance to say a 550 VA UPS, then that should be said.
And how about an easier way to figure capacity... it's been 30 years since my EE courses. I have a hard time figuring which way to put AA batteries in my TV remote! (just kidding, but simple formulas would help).