Hybrid 50cc Ultracapacitor Scooter

We’re all familiar with hybrid gas-electric cars these days, but how about a hybrid scooter that uses supercapacitors instead of batteries? Our hats are off to [Alex] from Labs Bell for the almost entirely-DIY conversion.

The hybrid idea is to drive the vehicle’s wheels with electric motors, but generate the electricity with a normal gasoline engine. This allows the hybrid to control the engine speed almost independently of the wheel motors’ demand for power, allowing the gas engine to run at its most efficient speed and charge up batteries with the extra energy. As an extra bonus, many hybrids also use regenerative braking to recoup some of the energy normally wasted as heat in your brake pads.

[Alex]’s hybrid scooter does all of the above and more. Since the stock vehicle is a 50cc scooter, any increase in acceleration is doubtless welcome. We’d love to see the scooter starting from stop with a full charge. Using supercapacitors as storage instead of batteries is a win for charging efficiency. In urban stop-and-go traffic, the natural habitat of the 50cc scooter, the regenerative braking should help further with gas consumption.

What’s most impressive to us is the completely DIY hybrid control unit that takes some simple inputs (wheel speed and throttle position) and controls regenerative braking, the gas engine’s throttle, etc. Since the hybrid control system is currently under development, there’s even a button to switch between different trial algorithms on the fly. Very cool!

Oh yeah, and [Alex] points out the fire extinguisher on-board. He had occasion to use it for his hybrid motorcycle V1. Safety first!

40 thoughts on “Hybrid 50cc Ultracapacitor Scooter

          1. I have a better idea:
            Girls ride whatever they want. Men ride whatever they want.
            This will come as a great surprise to many people, but it is exactly the reproductive organs that a person is born with that defines their gender, NOT what they like or what they do or how they feel or any such thing.

    1. Man card only gets lost if it’s a “liquor-cycle” If it’s two wheels, and traveling on the same roads as the Cages, then, at least as far as I’m concerned, he gets some respect.

  1. Real motorcycles have had to use 4 strokes only for more than 30 years. Why are these sickening stinkin oil farting engines still legal.
    Not slamming the project just the engine. I hardly ever see or hear a real motorcycle anymore. Just a lot of very noisy untagged no-peds.
    No-peds should go all electric. Small engines make more pollution than big ones.

    1. I strongly doubt that is a two-stroke motor. Remember, it is aimed at your slightly more tech-unshavvy masses. Expecting them to figure out the ratios of 2t oil and the like when filling up at the petrol station is a recipe for disaster. I have not seen a road vehicle with a 2t engine that has been made in the past 10 years. In South Africa 2t is only reserved for chain saws, bush cutters, racing motorcycles that are not road legal and older diesel engines.

        1. Wow that’s really interesting. I have never seen such a pump where I live! Motorcycles are not as popular here as regular cars. People die on them here so we prefer cars. But I assume in countries where you have millions of motorcycles it makes sense to have the proper fuel at the filling station.

        2. Vietnam has the highest number of motorbikes per capita in the world, so I guess that makes sense. Some of them are truly ancient, awesome, and unique (the neon pink one branded ‘Attila’ comes to mind). I’ve seen some semi-homemade ones too, a couple of them nice.

      1. I didn’t see a mixing pump in the last years, but anyway I’m wondering: Don’t you know the self-mixing vehicles? You fill in gas (and sometimes Oil) and there is a pump mixing oil and gas?

        1. Same in Spain, mopeds are VERY common for short distance commutes, and pretty effective in cities with warmer weather, and for the last 10-15 years they all have a mixer in the carburator, you just fill your fuel tank with gas, and everry 10 or 15 tanks you would have to fill the oil tank too (there a dash light that will warn you). No need to me messing with mixing by yourself, using those small 100cc oil tubes on each tank, etc. And they work like a charm.

          1. In my experience the oil mixer always gets gummed up after a while and the engine seizes up. Then the engine is unjammed by beating the piston down with a block of wood and the piston rings are replaced, and then it’s cleaned up and sold to some poor sod along with instructions to add oil to the fuel.

            They’re not so much mixing the oil with the fuel, but simply dripping it down the intake by a small hole, which fills up with residue or dirt from repeated refills.

      2. There are many two stroke scooters and mopeds on the road, and that’s a scooter, not a no-ped, no-peds are mopeds without pedals. It would appear to be 4-stroke as well. To blanket two-strokes as being more polluting is little much. I mean Tomos wouldn’t have been able to sell the A55 like they have. One company that managed to sneak through by designing an engine that passed the EPA’s requirements. Took a Honeycomb cat in the exhaust and other design changes but they got it done.

        They have also used an oil injection system for many years, a pump is driven from the crankshaft which pumps oil into an inlet on the intake.
        Real motorcycles have had two strokes well after your so called 30 years as well and some, mostly racing bikes, still do today.

        I doubt you’ll see much more decline in the use of two strokes from where we are today, with the changes and improvements in technology I’d bet that we see more, cleaner two strokes.
        You have a whole R/C market which relies on them as well but I can’t really speak on that front.

        I ride a moped everyday I possibly can while the roads are good. I drive on average ~30km perday getting to work and back.
        If I put $5 worth of gas into the bike, I can get to work and back for 2 weeks.
        That’s 300km. If I put that same $5 worth of gas into my truck, I might make it to work, but I might not make it home.
        To get to work for 2 weeks in the truck I haven’t figured out, but I’m pretty sure just guessing, that I would pollute a whole lot more using the truck, just due to shear volume of gas being burned. And yes I’ve seen the Mythbusters episode.

  2. Unfortunately, any efficiency gains you get from optimum engine speed, is swamped by the generator->battery->motor losses. (with going in and out of the batteries the place where most of the losses happen) Its really difficult to get something that complex to have lower losses than a metal shaft, and a gear or two.

    There is also a weight penalty, you need a generator big enough to take full output from your engine, and the electric motor has to be big enough to supply all the power you are going to have. With a parallel hybrid (like almost all the currently sold car systems), your generator only has to be big enough to support the max charge rate of your power system, and the electric drive motor only needs to be big enough for the output of your storage system, as it will be adding to the engine output, not replacing it.

    On systems with currently available batteries, the recharge rate is well below the discharge rate, so the generator can be quite small. In the case of the supercapacitor system, they could be close to the same size. If you go with the “electric turbo” like system that honda uses, they can be the same motor. (really saving weight, but it means you can’t move on electric drive alone).

    Yea, I used to think series hybrids were the obvious thing, after all diesel electric locomotives are series drive, just no batteries. But that system exists because getting power down to the wheels mechanically is hard at the power levels and number of direction changes needed). Add enough gears (especially right angled) and combined with no losses from batteries, and they make sense, especially since you need your locomotive to be heavy, otherwise its wheels slip.

    Yes, I have owned a hybrid vehicle (parallel, multi-motor) for the past 14 years. Long enough for some weird age related issues to crop up. Drive train has been fine, still on the original HV battery. Instead the problems have all been related to operating on New England’s salted winter roads.

    First issue was with a vacuum operated flap valve in the exhaust system getting stuck. The latest: trouble codes from the evap system. Turns out the hose clamps had rusted away, and the various bits of tubing were letting normal air in. I had assumed that one of the 10 hoses had given in to dry rot, so I started tugging on them to find the bad one. Instead of a broken hose, they just pulled off the barbs, with no resistance. I replaced the clamps with stainless worm gear clamps, and so far so good. (It also became obvious that the evap system was first assembled to the not yet installed gas tank, then the whole assembly was bolted into place. Tightening some of the clamps, not having dropped the tank, and especially with my hands (big, meaty, but with fairly short fingers for their size), was special…)

    1. I’m quite sure booth the petrol and the electric engine is mechanically connected to the engine. While it’s not spelled out directly on his site I guess charging the caps when up to speed just uses a bit of “generative breaking”.

      I have a full-electric eu-25 moped, I don’t use it much now (walks to work), but earlier I used it to work (3.5km one way) for a few years, a very nice mode of transport. In the end the total cost of ownership was about the same as the buss fare.

    1. This setup uses supercaps instead of batteries, virtually removing the issue of battery internal resistance losses, which very well may fix the issue. Reading your response, I also wondered about other applications of hybrids in this fashion, like diesel-electric trains and heavy construction equipment. I believe that in the case where transmission loads are high, the weight and reinforcements required to make a traditional transmission work result in a lot of weight and parasitic energy losses.

      The argument you make also only applies if you’re keeping the same sized engine as you started with. Vehicles with this type of transmission, when combined with energy storage can get away with much smaller, more efficient engines. They only need to be powerful at a specific rpm, which allows them to be optimized for that speed, and they don’t need to be powerful enough to move the car, allowing them to be very small and light, since their power output is stored over time.

      Now, only my first point applies to this scooter, but I’d like to see if he’s actually getting improved efficiency.

  3. I was surprised that most of the criticism targets not the mod but the vehicle itself. Here in Poland any adult is allowed to drive a sub-50cc with no license at all. Within the city borders a 2T scooter/moped/light motorcycle is a very efficient alternative to everything I could think of: municipal communication, bicycles and especially cars! Not to mention that some 2T 50cc mopeds allow you to reach 80kph (50mph) with no sweat. Acceleration is not that bad, after all power/weight ratio is what matters, besides there’s little point in blasting off like a rocket on a daily commute. All this under 2.5 litres/100km (94MPG).

  4. Very nice!

    I would like to see a version that has no transmission, where the gasoline motor does nothing but provide electrical power. Might be able to shave weight off that way, using a motorcycle alternator that has no permanent magnets perhaps?

    1. that would be easy to build. have considered putting a small diesel generator on a trailer behind an electric bike for long voyages, but then that kind of defeats the purpose of going electric, unless you have some kind of clean, renewable biodiesel or something. Still, it would be more efficient converting the fuel to electricity than going through transmissions and all that. Super/Ultracapacitors would really make it worthwhile.

  5. I was going to say I don’t understand why/how you’re using a transmission with a hubmotor, but then i realized that this is a hybrid, and I also use a transmission with my hubmotor. except mine is a human/electric hybrid.

  6. I’m not quite sure i understand the mode of operation. It sound like when you take off from a stop the motor is idling and it’s running on capacitor power. Then, at some point, the caps discharge, the motor revs up to drive the bike and recharge the caps. If you’re still at a lowish speed, maybe the caps take over and cycle repeats? Or maybe the caps only drive it at takeoff?

    Very cool and well executed though in any case.

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