Capacitor Packs? Why not?

I found a Supercapacitor. I checked the specs. Why don't we make a pack out of these things?
Help a newb out.


Rated Capacitance: 3000 F
Capacitance Tolerance: -10%~+20%
Rated Voltage: 2.7V
Surge Voltage : 2.85V
Rated Current: 600A(25C)
Max. Current: >1100A(25C)
Leakage Current : 2mA at rated voltage for 72 hours(25C).
Max. Stored Energy: 3.04WH.
Specific Energy&Gramimetric rate: 5.7(WH/KG)

Max. Internal Resistance(100A,mohm,DC): 0.65mohm.
Max. Internal Resistance(100Hz, mohm,AC):0.85mohm.
Operating Temperature : -40°C~+65°C
Storage Temperature: -40~ +70°C
Temperature Characteristics: +70°C,the absolute value of capacitance drop divided by capacitance≤30%,ESR≤initial measured value -40C,≤ the absolute value of capacitance drop divided by capacitance 50%,ESR≤3times initial measured value.


Load Life: 1000h,+70°C±2,rated voltage the absolute value of capacitance drop divided by capacitance ≤30%,ESR≤4 times initial measured value.

SHelf-Life : 1000h,+70°C±2, the absolute value of capacitance drop divided by capacitance ≤30%,ESR≤4times initial
measured value .

Moisture Life : +40°C±2,90~95%RH,240h, the absolute value of capacitance drop divided by capacitance ≤30%,I≤2times Initial measuredvalue. ESR≤4times initial measured value

Circulation Life: Voltage 2.7V~1.35V,temp.+25°C,Circulation
charging and discharging 500,000 times, the absolute value of capacitance drop divided by capacitance ≤30%,ESR≤3times initial measured value .
Dimension: D.63*L140mm
Net Weight: 530g.

5.7Wh/kg

I use 185Wh/kg cells. Those caps hold an order of magnitude less energy than even lead.

liveforphysics said:

5.7Wh/kg

I use 185Wh/kg cells. Those caps hold an order of magnitude less energy than even lead.

Click to expand...

He hit the nail on the head.

Energy density is painfully low for super capacitors, around 2% of what something like lifepo4 will have.

https://en.wikipedia.org/wiki/Energy_density

Super capacitors aren't so super. A few suggest pairing a super capacitor with a battery as a way to potentially eliminate the C rating choke point (assuming you don't completely drain the super capacitor), the larger pack would charge the super capacitors. I don't know how all that would work out and such, but if you need extremely high capacity ratings at affordable pricing, that might be a route. Otherwise there is lipo (dangerous) and a123.

Ok, thank you so much guys! However, I'm assuming that for short distances and super fast charge times, this capacitor pack idea would work?

Better for stationary applications I'd think. There used to be talk of using caps to allow bursts of high amps by using them along with batteries. Then lithium batteries became better, and or just available.

if the capacity can be brought up to lith standard - this would be the future long life cycle and charges within blink of an eye.... there's buses in japan using capacitors that charge up between bus stops

Brief pulse of regen stored power to help get moving again, these things may find a practical use.

With lifepo4, many might carry around 20 lbs for a range of 45 miles on an upright ebike. With super capacitors, your range would be less than a mile, in theory, with 20 lbs of super capacitors.

Another issue is you cannot charge super capacitors effectively pretty close to anywhere. You could surely max out a large capacity outlet, but you could do the same for other types of chemistry and have a range longer than a mile. The option of maxing out a super capacitor doesn't really exist almost anywhere in terms of available infrastructure. If you could find super capacitor chargers on every single corner that could fill a super capacitor at an incredible rate, this might be a different discussion. The truth is, many of us might struggle a tiny bit to find a 15 amp outlet in public.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=52560 This thread might interest you.

Tek said:

Ok, thank you so much guys! However, I'm assuming that for short distances and super fast charge times, this capacitor pack idea would work?

Click to expand...

And remember a capacitor drops in voltage fast, you'd need a DC-DC converter to keep consistent speed so there's losses there too.

Tek said:

Ok, thank you so much guys! However, I'm assuming that for short distances and super fast charge times, this capacitor pack idea would work?

Click to expand...

Just do a search on Capacitor here on ES, and there are a number of threads discussing and re-discussing this concept, with discussion that explains why it isn't really as good as batteries, for most uses.

(yes, you will also find lots and lots of unrelated threads, but the subject line should tell you which ones you want. )

davec said:

if the capacity can be brought up to lith standard - this would be the future long life cycle and charges within blink of an eye....

Click to expand...

except that the energy density ( Whrs/cc) is still way off.. IE they are too big/ bulky for a Ebike.

Sorry guys, one more question. What chemistry allows the most brutally fast charging? Good run time would be nice but I really don't care so much. Fast charge, stable/safe and high power output are most important.

The Turnigy Nano 'Tech can charge at 8C. Thats pretty brutal. They are readily available. But may not meet your definition of stable/safe......

A123 26650 cells charge up to 4C and will be safer, but bulkier.


Higher charge rates will generally mean shorter life cycles.

at the recent evchallenge in newcastle australia, two entrants ( motorised bikes) were using supercap banks in parallel with the batteries, they used them to solve the problem of the bms tripping under high load

Hillhater said:

davec said:

if the capacity can be brought up to lith standard - this would be the future long life cycle and charges within blink of an eye....

Click to expand...

except that the energy density ( Whrs/cc) is still way off.. IE they are too big/ bulky for a Ebike.

Click to expand...

elon stated rather than said:

we could see a breakthru in an area which i have some familiarity which is ultracapacitors, essentially a capacitor based architecture.
there's nothing that exists today that has the energy density that's in production.
so sometimes you'll see things that are announced, like there was the fast charging of a cell phone or something.
and you can do very fast charging with a capacitor but the range that you'll get, the energy density is still far too low.
but i'm increasingly optimistic there'll be a breakthru on the energy density front, but it's not anything people are publicly aware of.

Click to expand...

http://www.youtube.com/watch?v=n3AcKTmaoE8#t=3590

Ykick said:

Brief pulse of regen stored power to help get moving again, these things may find a practical use.

Click to expand...

They are used by Toyota for the LeMans 24h race exactly like that. I would see it for an ebike to regen at stoplight and power on the beginning of the acceleration to protect the battery pack from the surge current needed by the motor. Because of the low energy density one can't take them seriously for propulsion, but for surges they should be ok.