www.robowars.org

RoboWars Australia Forum Index -> Technical Chat

Motors info
Goto page Previous  1, 2

Post new topic   Reply to topic
  Author    Thread
Knightrous
Site Admin


Joined: 15 Jun 2004
Posts: 8492
Location: NSW


 Reply with quote  

TAT uses 18v Drills on 24v i believe and use a floating hub system to relieave the drill gearboxes from all the stress. Brett & Gary knows the details the best.
_________________
Team Knightrous

Post Tue Aug 10, 2004 8:06 pm 
 View user's profile Send private message
Spockie-Tech
Site Admin


Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


 Reply with quote  

TAT's drills are actually Dick-Smith drills (I dont think Bunnings had the XU1's back when we built TAT - our first Bot), and they are running on 12v in the video clip of it driving around..

I did try them on 24v and it had awesome power and literally did burnouts on full-power take-off's, but they would get smoking hot within a minute or so and it didnt need that much speed so we dropped them back to 12v and just ran the spinner on 24v.

The full-floating hubs are definitely worthwhile for a lightweight bot though, you can literally stand on The Acid Test without breaking anything and the gearboxes have had no trouble at all even carrying 28Kg around, the only failure it had was the laminations coming loose on the motor shaft and the isnide of the motor was going around, but the output shaft wasnt.. Laughing
_________________
Great minds discuss ideas. Average minds discuss events. Small minds discuss people

Post Wed Aug 11, 2004 9:16 am 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
Glen
Experienced Roboteer


Joined: 16 Jun 2004
Posts: 9479
Location: Where you least expect


 Reply with quote  

hey brett/gary,

would a 4 wheeler using 2x 100w scooters running off 30v drill nicads either blow the motors, ibc or run the batteries flat?

any advice once more appreciated.
_________________
www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

Post Fri Aug 20, 2004 7:21 pm 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
timmeh
Experienced Roboteer


Joined: 20 Jul 2004
Posts: 2517
Location: Victoria


 Reply with quote  

Maybe
if you can work out how long the drill nicads will last @ 12v if thats the normal rated voltage of the motors and then triple the amps of the motor cos motors use more amps the higher you over load em and that would give you an idea on 'if the batterys will go flat too quick and if the ibc can handle the amps Question

As for the motors surviving you overvolting them to 30v in the first place i dont know Confused

What are the batterys in one of those scooters are they sla's or nicads
Cool
And brett Very Happy how did you go about making those floating hubs on TAT what are they Question
_________________
Tim Team Reaper.


Last edited by timmeh on Sat Aug 21, 2004 11:19 am; edited 1 time in total

Post Fri Aug 20, 2004 8:24 pm 
 View user's profile Send private message Send e-mail
Spockie-Tech
Site Admin


Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


 Reply with quote  

The IBC is rated to handle ~36v. It will take voltages a bit higher than that, but you need to allow for the fact that freshly charged 36v packs will come off the charger at a higher voltage than their rated voltage.

For an *equivalent* amount of power, its better to make it with a higher voltage and less amps, than a lower voltage with more amps, since voltage doesnt produce heat in the IBC, but amps do. The power dissipation of the IBC's Fets is directly related to the amps passing through them, whereas an increase in voltage doesnt bother it at all (provided you stay under the rated voltage).

So in that respect, if you want more power, you are better off overvolting 12.4v drills to 24v than you are taking 9.6v drills to 18v say. In both cases, you are doubling the volts (and hence the amps), but one nets you more power..

As an example (ignoring efficiencies for now) if you were using 10amps at 12v on a drill motor, thats 120 watts of power (watts=volts x amps), and you double the voltage to 24v, you now flow 20 amps of current for 480 watts of power, or an extra 360 watts for an increase of 10 amps of extra load (heat) on the controller.

If you are running a 9.6v drill that produces 120 watts (the same as above) of power, that must be using 12.5 amps (more amps for the same power), which is immediately heating the controller more, and we now double the voltage to 18v, the current doubles to 25 amps but we are only getting 450 watts from the motor but putting an even higher stress on the controller. To get 480 watts of power at 18v you need to be using 26.6 amps or more than 6amps extra than you would at 24v.

Thats a little vague I know, but the bottom line is that higher voltage lower current motors will produce more power with less stress on your controller than lower voltage higher current motors will.

Running higher voltages and lower currents have other benefits as well with small voltage drops along your wiring and connections causing less of a power loss than they would at lower voltages and higher currents.

Also, the lower current demmands on your batteries will mean they will last longer than lower voltage batteries being asked to put out more amps will.

The main drawback of higher voltages is of course you need more cells to produce it, and you need motors that will take the voltage without melting down..

for anyone interested in fiddling about with this osr tof thing, the team tentacle torque/power calculator at http://4.47.235.131/tcr/torquecalc.htm can be very informative.
_________________
Great minds discuss ideas. Average minds discuss events. Small minds discuss people

Post Fri Aug 20, 2004 10:59 pm 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
timmeh
Experienced Roboteer


Joined: 20 Jul 2004
Posts: 2517
Location: Victoria


 Reply with quote  

Dose over volting your motors give you more runtime?
I picked this one up from franchesco.
_________________
Tim Team Reaper.

Post Sun Oct 03, 2004 8:35 pm 
 View user's profile Send private message Send e-mail
  Display posts from previous:      

Forum Jump:
Jump to:  

Post new topic   Reply to topic
Page 2 of 2

Goto page Previous  1, 2

Forum Rules:
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

 

Last Thread | Next Thread  >
Powered by phpBB: © 2001 phpBB Group
millenniumFalcon Template By Vereor.