Another one of my crazy projects :D

[Things]

Well, did a test rig of the setup today. The brushless motor's torque is pretty pathetic at low speeds, a LOT worse than I had expected, I can easily stop it by hand with little effort, however it seems pretty decent at higher speeds. If I had've known the low speed torque was this bad, I would have gone for the 168Kv motor instead of the 245, but oh well. Can always switch later with minimal effort if I need to. Just that in order to get the most torque with the 245kv motor, I'll need to be going 49km/h, which is a bit insane (with the 5:1 gearing). The 168Kv motor would have been more like 30km/h, which is really more appropriate if I get max torque at that speed. Unfortunately this ESC doesn't have sensor inputs, although there are similar ones that do if I really need it. I don't mind having to give it a decent kickstart to get going, but it definitely won't get you going from stop at all.

This ESC is a bit weird in that if you stall the motor, it'll try ramp up the current a bit to try get it going, but not enough to get it started under high load.

Trying to organise some cheaper postage on the grub screw sprockets, but I should have my machined prop adapter back soon enough I can test with.

Put some inline blade fuse holders on my batts, with 30A fuses, and made up a little XT60 "paralleler" adapter Eventually it'll be replaced by my BMS board though, so I can do per pack current monitoring.

 

[Fiddy]

op: can smell the victory burnouts!

 

[HitShane]

This looks fun! The consumer electric scooters are like $2k-$4k for a good one. How much is your build so far?

When I was a teen I had a gas scooter. Upgraded the intake and exhaust and 30mph was fast being that low to the ground It got 100 mpg fuel efficiency. One of these below...

Go-Ped® - Sport

 

[Things]

Well, so far it is roughly 2x $50 LiPo, $70 motor, $70 ESC, $40 charger, probably $20 or so in misc bits, and my BMS board will probably add another $60 or so onto that. Add $300 for the scooter itself and I should come out a fair bit under $800 for the completed project Will probably add a 3rd LiPo also.

Did a bit of playing with the ESC last night, and it's braking mode is actually going to work to my advantage, as it's basically built in proportional regen, it dumps the power back into the batts I recorded a 4A peak just from the motors own inertia alone.

 

[LaZeRz]

My 49cc scooter struggles to stop me at 60km/h with front and rear disc brakes, goodluck ;0

 

[Things]

Haha mad, what is it? I won't be going 60km/h on this, that's for sure Only brakes this thing has is a shitty band brake that even struggles with me on the original motor, regen should help a lot with braking.

 

[Things]

Well, my circuit design is nearing the end, just gotta quadruple check it then I can attempt to cram it all onto a PCB

 

[Things]

Well, a few days ago I actually put a bodge setup in the scooter and did a few tests, and my motor was overheating _rapidly_, as in, even going 200mm accelerating twice, the motor was already too hot to touch, and smelt really bad. Just lucky I was constantly checking as I could have damaged the magnets if it got any hotter!

Today, I put everything back, but this time I got out the ESC programming card, and set the motor timing to the highest setting. Well, it seems to have helped immensely with the heat issue

I just did a drive around the block, which is partially uphill, and motor was only warm, which considering ambient temp is around 30C, isn't bad at all. However, after riding it a few times, it became obvious another issue, with using a hobby ESC. That is, when you ramp up the throttle, the ESC is expecting the motor to gain speed rapidly like it would in an RC car, not slowly accelerate a huge inertial load.

So, if you ride the throttle well enough and don't try push it too hard for the speed you're going, it runs a lot nicer. This means generally you need to at least get a bit of a running start to get going, but once you're at a decent speed, it has grunt like anything. Even going up hill at decent speed, if you push the throttle too much, you can feel yourself grabbing on a bit tighter to the handlebars!

However, it brought up another issue with the wiring, mainly the 12AWG and 4mm bullet connectors on the motor aren't really up for the insane peak currents, they get very toasty!

But yes, I'm considering getting a small EDF and another much, much tinier ESC to drive it, which should give my motor an assload of airflow, equivalent to what it'd get driving a prop. I'll probably do motor temp monitoring too, so I can actively control the fan speed to save power. It'll sound awesome though, like a turbo or jet turbine on the scooter. Just need some flickering red LED's for an afterburner and it'd be legit

 

[Fiddy]

less acronyms more "feel yourself grabbing on a bit tighter to the handlebars!"

good progress interesting fan idea should sound like a beast!

 

[HitShane]

Awesome...

 

[Things]

Ordered a 168kv motor to try, see if it does any better at the lower speed range. With the 245kv motor, you have to almost get a running start before you can get decent acceleration. It will move you from a slight push, but you have to be lenient on the throttle, and the acceleration is probably even worse than the stock motor. Once you're moving about 10km/h, then it starts getting awesome

So hopefully with a slower motor, that threshold will be a bit lower. It also has 2 more physical poles, and 1cm longer, so the 2 more poles should instantly add another 15% more torque, and the extra length probably about the same too. Lower speed should basically double the torque of the 245kv

They are both the same diameter and mounting pattern, shaft diameter etc, so easily interchangeable.

 

[n2stuff]

Dan you crazy SOB. I hope you are wearing your safety equipment. LOL I am waiting for you to get the bugs worked out soon so I can copy it.

PS How's that big clock coming along.

 

[Things]

Safety equipment? Yeah, I'm wearing some shoes this time. First time I went out, was going along the pathway, hopped off and stood on the biggest piece of glass there was! Nice big deep cut in my foot

 

[n2stuff]

Safety equipment? Yeah, I'm wearing some shoes this time. First time I went out, was going along the pathway, hopped off and stood on the biggest piece of glass there was! Nice big deep cut in my foot

Yup That would be my luck too. The only piece of glass and my foot would find it. The lower KV motor will give more torque but it will cut down your top speed a bit.

Did you ever finish that big clock?

 

[Fiddy]

Shoes only!

 

[Things]

Well, up to about revision #2,340 on my controller/management circuit: https://dl.dropbox.com/u/203420/Scooter/Sheet2.pdf

Decided to just go back to bare bones monitoring instead of a full on battery protection chip. If the voltage gets too low, the uC will just beep at you relentlessly until you turn it off and charge it, should be enough of a warning

Unfortunately the parts for the epic clock didn't arrive in my first batch of stuff from down South, so that's on hold until I sort that out