couple of questions regarding drills

[woody]

I have used the sabertooth 25A controller on a 4 drill motor setup in Tron, it did all kinds of weird stuff so I never used that setup in the arena. The sabertooth is now in Seraphim and works very well that€™s with 2 12v Como drill motors running at 14.4v this is to be increased to 16.8v soon.
In Tron which has 4 9.6V drill motors running at 14.4V I now use a Sidwinder this grabs the motors by the scruff of the neck and throws Tron around the arena with no fuss at all. I agree with the rule with 4 drill motors in a feather the bigger the speed controller the better.

GENERALISATION.

A featherweight bot geared for 8 mph with 18v drill motors could ...under normal fighting conditions... pull 24 amps total....[ 4 motors = 6 amps each 2 motors = 12 amps each ]
with 12v motors 32 amps total
with 9.6v motors 44 amps total

gearing for 4 mph will halve the amps required......gear for 12mph and you would increase the amps required by 50%.

Speed Controllers with built in current limiters could / will current limit continiously if your bot is overgeared.

Note that stall amps per motor can be also excessive.

http://www.mabuchi-motor.co.jp/cgi-bin/search/e_use.cgi

[ady]

cheers woody, so if i have 12 volt drills x 4, with 75mm wheels how can i get a indication of what amps it would draw (tried the calculator link as above but struggled.
i still need to decide 100% on what voltage to use.

[woody]

OK.

http://architeuthis-dux.org/torquecalc.asp

Choose the 12v harbourfrieght , 3 inch wheels , 30lb bot , 2 motors per side & 1:1 gearing.

You'll need a value for the RPM/volt ...So YOUR drills rpm divided by 12.

Let's say 500rpm as an EXAMPLE ....so 500/12 = 41.66

Read the amps values etc output by the calc.


Torque (per motor) to spin wheels 162 oz-in
Amps (per motor) to spin wheels 4.9922 Amps
Theoretical Top Speed 4.4617 MPH
Total Peak Amps 19.969 Amps
Amp Hours Required - 3 Min 0.6989 AH
Amp Hours Required - 5 Min 1.1648 AH

[woody]

Seems the mabuchi search link didn't work........
Here's another.

http://www.mabuchi-motor.co.jp/en_US/pr ... _0305.html

Home Appliances & Cordless Power Tools

Drill
Screwdriver
Garden Tool

RS-380PH
RS-540RH/SH
RS-550PC/VC
RS-755VC/WC
RS-775WC
RT-8B7WA


Gives an idea of the possible motor specs.

[ady]

ok cheers.