e-Scooter 101

[PolarBearBob]

Hello EUC Faithful

I'm sure I'll get rapped in the mouth for this, but what goes into these wonders of creation? AC motors, DC motors, dual motors, controller functions, types of power, chassis materials, suspension systems. Can you build one DIY. Please share your wisdom with "A Bloody Tourist" as I've been lovingly referred too. Can you construct your own battery array for greater distance and speed? Are there any three wheel versions with all wheels powered?

I await your measured reply. 

PBB

[Esper]

Greetings and welcome to the forum.

The current highest performing, currently for sale, scooter that I know of is the Dualtron Ultra. 
But due to the tariffs, sales have currently been postponed.

If you want to build one yourself from the bottom up. I'd first learn about how to make a battery pack. You need to secure the battery pack in a case that is as dust/watertight as you can possible get it. There needs to be a cooling system so the battery doesn't overheat. For motors you are probably looking at getting an electric wheel hub. I would not know where to direct you to get one. The wheels vary in strength and thus speed.
For wheel size, depending on the speed you want, you would be looking for a 10 inch or more. Find a tire that is not too expensive and not too hard to replace but still in great quality.
I would recommend a tubeless tire. Solid is not good for high speeds and tube tires could get costly.
For controllers, you can buy an already made one from many vendors. They are not waterproof either so it would be a good idea to look for one that is suited to your area.
You need a charging port, a charger, and to make sure the charger and batteries are built properly otherwise you would end up with a fireball on wheels.

To be honest man. If I were going to make one myself, I'd make one thats gas powered with a lawnmower engine. 

[PolarBearBob]

How hot do these battery packs get? Give me some sort of reference. What kind of amperage and voltage are we looking at here?

PBB

[Esper]

That would ultimately be up to the size of battery pack you make and the control board you use. For the high powered scooters on the market today, they run at 60 volts, with almost 2000 WH. The scooters have built in heat sinks to help keep the battery cool. You are asking for hypothetical stats on a device that you would build to your own specifications. If you wanted you could run it at 100 volts with a 4000 wh battery and 2 wheels at 2000w each. You would have the final say in how hot to expect something.

Others may have more information for you that I am not skilled enough to provide.
@esaj I know I call you often, but this person could use some higher knowledge.  

[esaj]

Never owned or built either, but in my mind an electric scooter (whether it's the "kick-scooter" -type or one where you sit down) isn't that different from an e-bike, and much simpler than an EUC, since it doesn't need to balance by itself. Off the top of my head, for DIY-route, I'd look into smaller e-bike motors in the 10+ -inch range, and ready-made controllers which have throttle, just as example (I have no idea whether these are good or not, just basically what you're looking for):

The latter motor above is actually 16", which might be a bit large for scooter (but why not, if you can build the frame for it? ), there are smaller ones, and they may or may not come with drum brakes or disc brakes. EUCs use commonly 16S (67.2V max, 57.6V nominal, but most sellers round that up to 60V, so the above motor is meant to be used with 16S batteries) or 20S (84V max, 72V nominal) lithium-batteries. Common voltages in ebikes are lower, like 36V (10S) or 48V (13S), but there are some with 60V motors too. The "S" stands for "series", how many 3.6V (nominal) lithium cells are put in series to get the required voltage. Battery packs are usually marked with S and P (series and parallel), like 16S4P, meaning 16-cells in series and 4 series in parallel. If you want to build your own batteries, you'll likely need a battery spot-welder (which is different than the "typical" metal-working spot-welder), time to learn to use it and a lot of cells. Lithium-cells have the downside that they can go up in flames if "mishandled"...

Using anything else than lithium for batteries is not really effective, as other battery technologies are larger and heavier for the same capacity. Of course you could stack a bunch of car batteries on your scooter, but for the voltages required, you're going to have to put many (3-6) car batteries in series and that's going to take space and add weight.

The motors are typically 3-phase BLDC's (brushless direct current) / PMSM's (permanent magnet synchronous motor) and are driven electronically by creating an AC(-like) high power signal through computer controlled half-bridges (inverter). Making the controller yourself isn't really simple, especially when it comes to the software-side (hope you like higher level math on top of knowing C -programming language and microcontroller specifics ), luckily there are ready-made controllers available.

E-bike/scooter motor controllers usually come in a aluminum box with some cooling fins, and contain the necessary wires:

Of course the voltages for the motor, controller and batteries should be the same, the two latter being critical, technically you can drive a motor with different nominal voltage from higher/lower voltage, but the top speed will be different and possibly something like a 36V motor can burn with 60V set up (it pushes too much current through the motor and burns the windings). Personally I'd go only with one-wheel drive, getting the two motors to run at same speed might be an issue (although many commercial high power/speed scooters do have 2-wheel drive, like 1000W motor on both ends), and you most definitely wouldn't want your front wheel to start skidding while the back wheel still drives the vehicle forwards  

One option is to buy a kit which comes with the motor and controller, possibly other knickknacks and batteries, that way you won't have to deal with finding motor and controller that work together.

Whether it actually becomes any cheaper than buying a whole escooter from the start, I don't know. The motor with shipping (depending where you live) can cost >200€/$, a high-power controller (1000W or more) likely another hundred, and the battery packs with good quality cells and BMS can be 100-200€ per 16S1P (shipping lithium batteries internationally can also be expensive). For higher power/range, you likely want to have 4 packs in parallel. Then you need the controls (throttle), inner tubes, tires, mechanical brakes (the controllers have regenerative / dissipative braking, but at high speeds it may not be enough), shock absorbers (I actually saw a kit containing a front fork with suspension + motor somewhere), other frame materials and tools. Possibly lights, speedometer etc. The parts price in total can quickly go above 1000, and that's assuming you already have tools for metal working, like a welding machine, angle grinder and such, so I don't know if you actually end up saving any money, but if you're just more interested in building your own for the fun of it, then go for it.

 

No idea if the above scooter is any good, it was on sale for about 1300€ + 300€ shipping (from China).