Re: Car Battery for post-season bot
 

Eric,
I agree with Tom. If I read your post correctly, you want the reduction to give 850 RPM to the wheels. That sounds pretty high. I am out of my element on mechanical design here, but, backing into the calculation, a 6" wheel needs to turn about 170 RPM for 3 MPH. For a larger wheel that number needs to be reduced. A 15" wheel would only need 67 RPM. Is that what you get, Tom? Again, on the published curve, I think you want to design around paramater on the left side of max power. I would feel more comfortable for a mechanical guy to chime in here but I would think the 150 to 200 oz.in. part of the curve should be OK. Keeping the RPM up and gearing down multiplies the torgue and lowers the current.

Re: Car Battery for post-season bot
 

I dont want to take it 20, just know that if i get into a race, i can whoop som a$$. :) Well, i want it to go faster than what a normal person runs, which is about, im guessing because the walking speed is 3-5 mph, that running is around 10-13 mph. Do you think max speed is ok at 15 mph then? Im going to control the speed with a potentiometer next to the steering wheel. I doubt ill ever bring it that high when there is people on the track, but i find 15 mph ok. The pot will be not be contected to the motor, but programmed to slow the motor.

Tom, thanks for the reality check. Online on google... ahhahah google... well it says that the average human walking speed is between 3-5 mph, which makes sense due to the fact that in PE 10 min to do a mile, well im middle school for me it was, but that is so that they know everyone ran a part of it. 1h/5mph= 1/5 (60) *min in an hour* = 12. Aka the 12 min mile which senior citizen walk. So the average human walk is about 3-5 mph. Also, our robot, i am almost certain at top speed is more than 5 miles per hour. We use four CIMs to drive, as well as after the gear box, we gear it up a little.

So, is 15mph still too high?

Re: Car Battery for post-season bot
 

Eric,
10 ft./sec is about 7 MPH. Depending on your design, a device that gets up to 10MPH may get unstable on a rubberized track. You don't want to go fast and throw your ride on the ground. Remeber that CG is going to be inherently high in a ride with a person sitting up.

Re: Car Battery for post-season bot
 

so 10 should be good? I think ill stick to 10 then (as i wont take to full speed most of the time), as i dont want to mess up a track, especially when the new rubber tracks that Birmingham and my school, Granada, have. I got a lot of designing to do... thanks for all the help. I going with a four large CIM drive system, 2 on each the back wheels, and geared to 10 mph. That as well as a larger 12v battery with 4 spare 883's. I think im all set. Thanks again, all you guys, for the advice and information.

Re: Car Battery for post-season bot
 

you owe us jpegs when its up and running :^)

Re: Car Battery for post-season bot
 

Its a long way away. But if it gets approved, which im going to fight to get it approved, ill post pics and at least a couple of videos. The reason why it may not get approved is because of the previous thing where they smoked the victors. But im not going to let that happen. Now i have to do a write up for the proposal. There is way more than just being a go-kart, but i wont reveal what that is :) . But it will ROCK YOUR SOCKS OFF!!! ahaha. Well, back to chicken soup and designing, being sick really is a bummer.

Re: Car Battery for post-season bot
 

Go-Kart was declined :(
But im still using all of this info for another project that is just as cool, but underwraps until unveiling... :)