Brushless Razor e300

[vanilla ice]

Args!! Did you get the thinnest one they offer which is the cheapest one?? That is the one that worked out on mine, and without having to make it thinner. But my brake is larger in diameter. Yours looks thicker than I remember.. Im sorry it didn't work out easier.

[fizzit]

Yeah it's 3/16ths of an inch by 1 inch, which appears to be the thinnest they have. I bet it has to do with the smaller brake diameter. Oh well, I hope there's some way to make it work.

[vanilla ice]

I'm trying to think of an easy way to make the friction material thinner, but coming up blank.

[fizzit]

I really appreciate the help. I'm kind of wondering if it will wear in if I put it on and run it for a while, or if bad things will happen. The rotor can spin, there's just a couple of places on the pad that continuously touch it.

[fizzit]

You know, I just sanded a bit, and it sands really well. So I have a solution! Thanks again!

[vanilla ice]

Great! It seems a big waste both material wise and money wise to have to replace the whole thing just because the lining chunks up and falls apart. That is what mine did also.

[fizzit]

I just got it all put together and stuff 2 days ago. It works great and I can definitely feel it brakes better than my non-destroyed brake. Plus the temp stays way lower and it doesn't fade on the way down a hill, probably because of the 6 holes I drilled in the brake casing

[fechter]

I've seen a whole new one for around $20, but if your fix is working, that's great.

I've always had bad experience with band brakes on small wheels. I modified the one on my Zappy by filling in the inside of the drum with an aluminum disk to help dissipate the heat. It also had fins on the side of the drum. All this helped, but it still sucked on long, steep hills. If you have regen braking on the motor, it will help out the brakes a lot.


I really like your throttle interface. What are you doing for a 5v regulator?
I made an analog version, but it takes a lot of parts to do that way.
There are probably quite a few people that would be interested in getting something like that.

Adding some extra capacitors across the battery input wires would be a good idea. The stock caps are going to be stressed pretty badly and may fail prematurely.

[fizzit]

Yeah. I actually bought a whole new one but I wasn't satisfied with its performance, so I decided to try vanilla ice's suggestion to see if I could get better braking performance. And surprisingly, I did. Thanks again to vanilla ice

The e300 has a freewheel. Which is kind of nice, but then... no regen

The 5v regulator is just a normal LM7805. There's a cap directly soldered to the input and the bundle is heat-shrunk in-line. On the board itself there's a ceramic and another electrolytic cap just to be safe.

Hmmm... you've got me thinking now. Maybe I'll buy the parts for another and start tinkering with making it more refined, etc... One thing, have you encountered liability issues with selling a throttle unit? I don't want to end up like toyota

[fechter]

Just don't make it so the throttle sticks on.

I guess that's a worry, but I haven't had any problems like that.
The PWM throttle input is usually fail safe in the event the processor locks up or something.

It might be a thought to have some kind of safety feature to detect broken throttle wires. With a typical hall throttle, if the ground wire breaks, the signal will go a bit higher than it would for full throttle. This could be sensed and used to shut down the output. Same goes for a short between the 5v and the signal line.

Not all hall throttles have the same output characteristics, so some amount of programmability may be needed to compensate. Something like hold a button and run the throttle from zero to full and back to calibrate would be cool.

[fizzit]

That would be very cool! That way you would have failsafe AND fine-tuned throttle response.

Since the chip has an ADC left over, I'm thinking of also allowing the user to plug in a temp sensor or shunt, for optional current or temp sensing. That would probably be something I would have to manually program.

[Robomaniac]

Just don't make it so the throttle sticks on.

I guess that's a worry, but I haven't had any problems like that.
The PWM throttle input is usually fail safe in the event the processor locks up or something.

It might be a thought to have some kind of safety feature to detect broken throttle wires. With a typical hall throttle, if the ground wire breaks, the signal will go a bit higher than it would for full throttle. This could be sensed and used to shut down the output. Same goes for a short between the 5v and the signal line.

Not all hall throttles have the same output characteristics, so some amount of programmability may be needed to compensate. Something like hold a button and run the throttle from zero to full and back to calibrate would be cool.

In any kind of micro there is a thing call a watch dog that keeps a eye on the status of your micro. You have to reset the watch dog timer every X millisecond. In other words if you don't reset the watch dog fast enough it will reset the micro.
So if you micro "locks" up or anything, the micro won't be able to reset the timer so it will time out and reset the entire micro and start your code over!

I use it my PIC and maybe you can find that in the PICAXE.

Code: Select all

   setup_wdt(WDT_2304MS);  /*In this case you have 2,3 seconds to reset the timer */

   while (TRUE)    /*start an infinite loop inside main()*/
   {
           do something smart here but not to long
           reset_wdt();   /*you  must reset WDT every so often while awake*/
    }

In my scooter, the moment I press the brake, I go in this loop where I tell the motor to stop and do nothing else until I release the brake. The moment of panic simply press the brake.

Also you can simply add a foot switch, if your feet move (you fall) you could stop the scooter.
If you have potentiometer for the throttle,you could have a other voltage divider where "no throttle / no speed" equals 1V and then when you read 0 with the micro you know there is a problem. You could do the exact same thing with the MAX speed.

[Uncle D]

You've got a cool build going on. I also have an E300, but there seems to be quite a bit of folks modifying the E300 so I opted to build something smaller utilizing R/C components.

Anyways, I'm not sure its been suggested yet, but have you considered going to a larger diameter drum brake? I've used 90mm drum brake assembly on 8" tires and they'll latch on pretty good. However, it seems these band brakes, after a hard squeeze, they don't stop so well until they cool again-15-20 seconds or so.

[fizzit]

Thanks, Uncle D. Well I have those pocket bikes. One has a big drum brake, the other disc brakes. Guess what's in the works:

[fizzit]

Well I got the disc brake installed. If anyone's interested, let me know and I'll take some pics and post them