Just found another motor on ebay , it says its 12v dc and 100w , see it here http://cgi.ebay.co.uk/ELECTRIC-SCOOTER-SPARE-MOTOR-12V-100W_W0QQitemZ200052161265QQihZ010QQcategoryZ64676QQrdZ1QQcmdZViewItem
Would it be worth it overvolting it to 24v for the added power ?
_________________
If practice makes perfect and no one is prefect, Then why practice?

More power at a given voltage yes as in if you are limited to around 20 cells because you are running 18volt drills as drive of the same pack.

I prefer to up the voltage to get the power. 30 cells in series instead of 2 lots of 15 in series parallel for instance.

Remember magnetism is proportional to the current and the length of the conductor so a long wire at low current does the same job as a short wire at high current, this translates into lots of turns and more volts to push the amps vs. less turns of heavier wire, less volts but more amps.

As the amps go up more strain and heat. If a controller can run at 24volts and switch a given number of amps and the same at 12volts I would prefer to run the bot at the highest practical voltage and use less amps.



Just re read your question, with the size and weight of your disc more power equals faster spin up or more revs or both depending on ratio.

The harder you hit the more damage you can inflict on yourself, going too fast and you limit bite, Plan B worked best with only one tooth I think and Cyclonite tried to polish things to death.

If you like to brag about your “joules” go for it.

I work on the philosophy that you have to finish to win so our bots are a bit conservative. Intercooled batteries etc a bit too extreme for me.

To answer your question
Trade off some reliability and run time for a bigger hit? I would probably get one at that price and try it .

Thanks a bunch Rotwang and everyone else ! , just bouught one off eBay , so my final decision is to run the 12v at 24v and have either a 1:1 or 2:1 ratio
_________________
If practice makes perfect and no one is prefect, Then why practice?

Happy to help out, just wondering how you are driving it, toothed belt, V belt, Friction wheel, chain ETC?

One project Brett and I have on the backburner is a motor dyno, as usual I was doing the fabricating and Brett was looking after the electronics, so far we haven’t got very far with that project; one of these days when I run out of things to do but it would be nice to just run something up and get a nice print out that means something.

Car club dyno day was last Saturday.

quote:

---

just wondering how you are driving it, toothed belt, V belt, Friction wheel, chain ETC?

---

I think that’s a good choice.
With bender we are running a radiator fan motor on 12 cells through a v belt.
It is set up nice and loose to save power and give it some slip, works fine. Recommend the internally notched type, they flex easier and waste less power.

OK , got the motor today and it is sweet Just tried it at 24v and it goes like a dream . Since im doubling the voltage could I get some help working out the possible outputs specs from the motor.
@12vdc it gives 100w 2700rpm, just need help with the 24v specs. Hopefully i should start building soon ,just gotta get Glen to help me with the design ,might even make a build thread
_________________
If practice makes perfect and no one is prefect, Then why practice?

quote:

---

Originally posted by Ali:
Since im doubling the voltage could I get some help working out the possible outputs specs from the motor.
@12vdc it gives 100w 2700rpm, just need help with the 24v specs.

---

Just remeber that the motor isn't designed for that kind of power. It's ok while is spinning, but be careful with the starting current and stall current.

Do the commercial speed controllers come with a current limiting feature? Otherwise it might be a wise move to install one, to stop your motor from cooking itself (not a pretty sight).

Thanks for the info Phil
I will be careful about the stalling currents and stuff like that , but for a motor that is cheap compared to others I'm not that worried
For turning on the motor I'm not even using the scooter speed controller ( I joust bought the motor) I'm probably just going to have a microswitch and a relay setup.
_________________
If practice makes perfect and no one is prefect, Then why practice?

Hey can anyone tell me how to get the brake drum off the 100W oatley scooter wheels?

http://secure.oatleyelectronics.com//images/scd2.jpg

I'm considering trying to drill the headless-bolt-thingys out, but since I know other people have already removed them somehow (eg. reboot) I thought I'd ask, is there a better way?

PS. My first post

they are just a press fit, get a flat head screwdriver in under each side and push UP and it just slides out
_________________
www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

Cheers Glen, that sounds a boatload easier!

Does anyone know the stall current for a 300W scooter motor (but I think I actually own 280W motors).
http://www.unitemotor.com/Product/ViewProduct.asp?ProductID=60
The chinese website is useless for that sort of thing but used their numbers to calculate 68.26A. Does that sound right? That'll explain why the IFI I use to drive Avenger's axe never got warm even without a fan. I actually thought it was twice that much, which would have cooked the IFI.

A simple way to work it out is to perform a locked rotor test. Simply lock the rotor and apply a fraction of the running voltage, so that rated current flows. Then use your voltage and current measurement to work out the motors resistance. Use this resistance to determine the current at full voltage with a stalled load.

You don't actually have to go to rated current, but I'm just used to doing it that way for uni.
_________________
They say that he crossed the fine line, from insanity to genius.