Large, charged capacitors are pretty frightening. Batteries too, but their discharge rate is limited to the speed of the chemical reaction.
Are capacitors not limited by a chemical reaction?
[deleted]
What is a Lithium-ion capacitor?
21–30 of 37 posts
Re: What is a Lithium-ion capacitor?
#22Large, charged capacitors are pretty frightening. Batteries too, but their discharge rate is limited to the speed of the chemical reaction.
Are capacitors not limited by a chemical reaction?
Not generally, no. Capacitors usually store electrons in a conductor so they are free to move instantly. Movement of free electrons within a conductor is not considered a chemical reaction.
Re: What is a Lithium-ion capacitor?
#23Dumb question but I though capacitors store energy and not power?
Power is just the time derivative of energy, like velocity is the time derivative of position. Both batteries and capacitors store energy, which they can release at some given peak and average power. Batteries tend to focus more on energy density (energy stored per weight), while capacitors tend to focus more on power density (rate of energy stored or released per weight).
Re: What is a Lithium-ion capacitor?
#24Earlier quoted context omitted.
Are capacitors not limited by a chemical reaction?
Not generally, no. Capacitors usually store electrons in a conductor so they are free to move instantly. Movement of free electrons within a conductor is not considered a chemical reaction.
aka a lightning bolt
Re: What is a Lithium-ion capacitor?
#25Large, charged capacitors are pretty frightening. Batteries too, but their discharge rate is limited to the speed of the chemical reaction.
Are capacitors not limited by a chemical reaction?
Limited by material. They store electric charge by using thin layers of insulating material and pooling negative charge on one side and positive on the other. You can puncture the material and release energy as a typical conductor, it's not stored chemically.
Re: What is a Lithium-ion capacitor?
#26Dumb question but I though capacitors store energy and not power?
Power is just the time derivative of energy, like velocity is the time derivative of position. Both batteries and capacitors store energy, which they can release at some given peak and average power. Batteries tend to focus more on energy density (energy stored per weight), while capacitors tend to focus more on power density (rate of energy stored or released per weight).
I think that just reflects that the typical usage for a capacitor is smoothing out some very spiky load that runs at a high frequency, say a microcontroller running at 100MHz. The average power needs of the MCU are low, but it's drawing almost all of it in a big burst on every clock tick (10ns).
Power supplies handle that badly, and the pulses turn your supply traces in a big antenna and suddenly you're an unlicensed FM radio station.
So for the capacitor that's put in place to buffer that load, the total capacity is important, but what really matters is that the part can manage that 100MHz charge/discharge cycle.
Re: What is a Lithium-ion capacitor?
#27Earlier quoted context omitted.
Not generally, no. Capacitors usually store electrons in a conductor so they are free to move instantly. Movement of free electrons within a conductor is not considered a chemical reaction.
aka a lightning bolt
Not really as large capacity capacitors (this one seems to be 4V) tend to be low voltage as well. You can touch the terminals without harm but attempting to short them is going to be, er, entertaining. I have accidentally touched a 200V capacitor and it was not fun.
Re: What is a Lithium-ion capacitor?
#28Earlier quoted context omitted.
It’s the best part of any electric drivetrain. Especially when you can remap the throttle to really launch from zero. :) (I find that electric acceleration makes highway merging much safer.)
My EV has the opposite problem, something like half throw is full throttle and then the rest of the pedal does nothing. They do it for marketing reasons but I still don't like it
My ICE car does the same. The only use for almost half of the pedal travel is shutting down the speed limiter when it's active, with no change at all when the limiter is off.
Re: What is a Lithium-ion capacitor?
#29Earlier quoted context omitted.
It’s the best part of any electric drivetrain. Especially when you can remap the throttle to really launch from zero. :) (I find that electric acceleration makes highway merging much safer.)
My EV has the opposite problem, something like half throw is full throttle and then the rest of the pedal does nothing. They do it for marketing reasons but I still don't like it
That’s annoying. The Genesis throttle maps are what you’d expect: Eco counteracts a leadfoot, Comfort has good pickup, Sport is borderline irresponsible in neighborhoods, Boost is unreasonably fun.
Re: What is a Lithium-ion capacitor?
#30For anyone that wants to see a real data sheet: Nominal Voltage: 4.0V High Power and Energy Densities Cycle Life > 50K Cycles Capacitance Range: 10F-1200Farads https://abracon.com/product-lineup/frequency-control-timing-... Note that the original data sheets said that these could be wave soldered. ABSOLETLY NOT. Even hand soldering they must be treated with respect, a lot of respect. One of the major problems with th…
So it's some of the performance of a supercap (hundreds of thousands of cycles, up to million-hour lifetimes with a bit of care, less finicky about soldering) with all of the safety of a LiIon battery? I think I'll give it a miss, although it probably has niche applications like use-once military systems where you're not worried about long-term performance before it disassembles itself.