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About the application of supercapacitor on electric bicycle or electric motorcycle

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    #31
    I'm not very good at this. But it looks to me like 12S1P would be needed for 48V. I'm guessing 50A would be available. So a separate controller would be usually needed to boost a 48V 30A 1500W BBSHD.
    So the questions I have are-
    1. How long would the 50A power from this last. I'm thinking of it as a NOx kit type of add on device.
    2. Since 50A is usually accomplished by overvolting is this just a bad idea to start with? Would the existing 2500W controllers be good enough?
    3-Would this produce 80A if the battery wasn't switched off? In other words I wouldn't want the power to just recharge the batteries, or damage them.
    4-Would 15S1P be the way to go? Then could a diode work for this. Running a 63V to 52V overdrive cycle with a48V. main battery?


    I assume these are more expensive than batteries at this point. It's an interesting product. I'm just wondering what it might be good for.
    Last edited by Retrorockit; 06-04-2020, 08:20 AM.

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    • ZGchina
      ZGchina commented
      Editing a comment
      1. How long would the 50A power from this last. I'm thinking of it as a NOx kit type of add on device.
      - It will last across the entire operaing vlotage range.

      2. Since 50A is usually accomplished by overvolting is this just a bad idea to start with? Would the existing 2500W controllers be good enough?
      - Depends on the controller since it governs ampherage draw will be governed by PWM. It's a good idea to up-spec your controller.

      3-Would this produce 80A if the battery wasn't switched off? In other words I wouldn't want the power to just recharge the batteries, or damage them.
      - Overcurrent will definitely damage the cells. Please stick to the velues indicated in the data sheet.
      4-Would 15S1P be the way to go? Then could a diode work for this. Running a 63V to 52V overdrive cycle with a48V. main battery?
      - The working voltage range of these cells is 37.5 to 63V and 48V li-ion batt pack (13S) normally works between 36 to 54.4V. 13S (32.5V to 54.6V) will be enough to be paralleled to the li-ion pack.

    #32
    These aren't direct cell replacements since they are intended to run over a much larger range of voltages - to get the capacity out of them they should run down all the way to 2.5V which unlike Li-ion shouldn't hurt them a bit. Also a "48V" battery is 13s and a "52V" is 14s since the "nominal" Li-ion voltage is 3.7V (13s = 48.1V, 14s = 51.8V)

    Point being is that at full charge just like a "48V" li-ion a 13s pack would be 54.6V but unlike a Li-ion which we'll usually set LVCO at around 42V give or take a volt or two, these would need to discharge well past that down to 32.5V so not only are Li-ion BMS's unsuitable for these, the wide range is too much for most controllers. Consider that at 30A at 54.6V you'll get ~1640W but at 32.5V only 975W... another way too look at it is if you want to still get 1640W at the low end you'd need a whopping 50A!

    The solution to implementing these is a different management unit in the battery (they have different care and feeding than Li-ion regardless) that boosts the voltage to a more steady voltage and/or a controller that doesn't mind the wide range


    While capacitors can offer a reasonable energy storage system they tend to be larger and more expensive for a given amount of energy. The data here shows that the cells hold somewhat less than twice the energy of the Li-ion cells in present use but they have 4.4x the volume - although it appears they are rectangular and so will likely pack more efficiently. Another number I'd like to see aside from cost is the leakage current.


    Anyway, just a different animal that has to be looked at differently... right now these types of capacitors or more often found as the energy reservoir for capturing braking (regen) energy and not for the primary storage due to the limitations I mentioned and their ability to charge and discharge *much* more quickly than Li-ion cells...

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      #33
      Thanks for the 12s,13s info. that's why I said I wasn't good at this. The spec. sheet for these showed up to 4.2V. for these so they may run a little different there anyway. I guess the 80% discharge meant they can use 80% of the power. I though that went down to 80% Voltage "sort of" like batteries. But that would be unusual for capacitors. I was thinking of it as a piggy back device due to the size, and cost issues. A regular 48V range battery, and a 60V capacitive booster bank. But as Voltage drops the Amps will go way up. They list 50A in the spec. and 50Ax60V=3000W, and 50Ax48V.=2400W. I'm still curious how long they would run before they got down to battery Voltage? Might not be worth the trouble, but you have to start somewhere. A couple minutes of 3kW could make things interesting.
      Last edited by Retrorockit; 06-04-2020, 10:41 PM.

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        #34
        Since the energy (e.g. W·hr) in a capacitor is equal to CV2/2, most of the energy is at the higher voltage side of things

        OTOH I don't think it's worth the trouble

        I'm a reasonably sharp guy, patent in process and everything... but I tend to subscribe to the thinking that if it made good sense, someone else would probably already be doing it

        Like mentioned these types of capacitors already see use in regenerative braking - nothing as small as bicycles though, mostly very large vehicles with some use in cars

        Maxwell is a leading supplier (they call them "ultracapacitors") and from their website:

        Regenerative Braking and Peak Power

        Ultracapacitors’ unique performance characteristics make them ideal for capturing and storing braking energy generated in trains, trams, trucks and automobiles – and then releasing it on demand. They can deliver peak power for drive systems and actuators in a variety of vehicles.


        Ideal for UPS Backup and Pulse Power

        In UPS applications, ultracapacitors ensure that critical information and functions are available when supply voltage dips, sags, drops out or surges, or during a battery changeover. Working in tandem with a complementary power source, ultracapacitors reliably supply energy in peak power demand conditions, reducing strain on the primary source and extending its usable life.


        Modular Storage Solutions

        By linking multiple cells in a single module, Maxwell Technologies’ ultracapacitors can meet or exceed the storage and power needs of today’s most demanding applications. Based on either our K2 or BC series, modules provide a dependable, cost-effective solution for UPS, telecom, automotive, transportation, and other applications, reliably performing through hundreds of thousands of recharge cycles.
        No mention of bicycles - I'd suggest due to cost, size and the additional complexity burden on the electronics

        I've been paying attention to them for quite a while but I think they're still a ways off to compete with Li-ion for bicycles


        On an oddly different note I've owned a capacitor based cordless electric screwdriver for at least ~20yrs. Cool little device. I use electric screwdrivers so infrequently owning a battery powered one makes zero sense. The batteries would like only live for a small handful of uses and then die because I either leave them in the charger topped off (we all know that's bad) or let them sit and discharge until death. The capacitor based one doesn't last for all that many screws but it only takes 90sec to charge from completely empty to 100% and if I'm using it a lot less than a minute gets me to the next round... barely enough time to take a hit from the beer and sitting around discharged doesn't hurt it one bit =]

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          #35
          The thing is due to the Ebike legal climate adding another 1500W to a 1500w motor may not exactly fall under the heading of good sense for a lot of people. Especially Corporate types.
          I'd still like to know how long 63V (15s x4.2V) 3000W of these would take to run down to48V 2400W or 40V. 2000W powereing a BBSHD?. Automoive alternator diode plates could handle the curent easily to protect the battery, and allow whatever device had the higher Voltage to power the bike as needed.

          This is from Maxwell's website.
          "Ultracapacitors complement a primary energy source which cannot repeatedly provide quick bursts of power, such as an internal combustion engine, fuel cell or battery. "
          That's pretty much what I'm sugggesting.
          Complementing a battery with a quick burst of power. It doesn't say no bicycle batteries allowed.

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            #36
            Having worked in trucking, and on airport shuttle busses, the reason these are being used there, is regen braking on stop and go commercial vehicles like city buses and garbage trucks is about 30% fuel savings. Fuel saving on an Ebike =0%. Not a lot of commercial incentive for someone else to do this for us.

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