R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Thread Tools Search this Thread
Old 08-18-2005, 06:41 PM   #1
Tech Addict
imjonah's Avatar
Join Date: Oct 2003
Location: Colorado
Posts: 704
Default Poor mans Dyno

I know, I should not be such a cheapskate and go out an by a real dyno, but......

If I take the motor I am testing and connect its shaft so it rotates another motor, when I power up the motor I am testing then I should be able to attach my mulit-meter(in 10 amp ammeter mode) to the tabs of the other motor and read amps output.

I can than compare the relative amps output of several motors or several different configurations of one motor. While kind of rough it will give me a benchmark to spot a weak motor or a motor with a potential problem.

I have read about using a resistor as a "shunt" when using a multimeter to measure amps, is this necessary in this case?

Is the above going to work or is it a waste of time?
imjonah is offline   Reply With Quote
Old 08-18-2005, 06:45 PM   #2
Tech Adept
handyrandyrc's Avatar
R/C Tech Charter Subscriber
Join Date: Oct 2003
Location: Salt Lake City, UT
Posts: 206
Send a message via ICQ to handyrandyrc Send a message via AIM to handyrandyrc

EXACTLY the principle behind the Bud's dyno I have. It uses a multimeter to give you reference numbers.

Basically, you've got to come up with a "baseline" motor -- one that you know works well on the track. All of your other motors will be compared to your baseline motor, and that will tell you whether it runs better or worse on the dyno. (On the track is another thing...) It can also help you figure out how to gear any given motor, as long as you can find that "gearing sweet spot" on your baseline motor.
handyrandyrc is offline   Reply With Quote
Old 08-18-2005, 07:59 PM   #3
Tech Master
Join Date: Nov 2003
Location: Florida
Posts: 1,154
Trader Rating: 1 (100%+)

Although one "small" step better than a non-load motor checker device for comparing motor A to motor B......you'd still be missing several of the "most" important determining measurements that a true dyno can give about a motor.........a true dyno reading is more of a mixture of several important readings that are taken into consideration......not just Amps at one unadjustable load setting.......Even if you were to use a good dyno like the turbo 45 and just looked at the one reading your going for, it would tell you very little about the motor since your only getting one very small piece of the pie........For example:you can find two motors that are almost dead even in the amp draw readings (under a specific given load) but the RPM's, Torque, Watts, and effeciency can be off the chart different..........so, mabe fun to play around with,(like the motor checkers) but not really valuable for much else..........
1/8 Scale: Tekno EB-48.2... Tekin RX-8 GEN-2 W/2050kv... Airtronix M11-X Radio... HiTec HS-7954SH Servo...

1/10 Scale: Associated B-5(rear motor)...Tekin RSX Gen-2 W/8.5t... Savox SC-1258-TG Servo
Joe B is offline   Reply With Quote
Old 08-18-2005, 08:50 PM   #4
Tech Master
kerry's Avatar
Join Date: Jul 2003
Location: Alberta, Canada
Posts: 1,157
Trader Rating: 1 (100%+)

if you dont have the funds to buy a dyno, then let the track be your dyno follow the ten basic steps on rebuilding a motor and let your lap times be your guide.
kerry is offline   Reply With Quote
Old 08-18-2005, 09:53 PM   #5
Tech Regular
RandomFellow's Avatar
Join Date: May 2005
Location: Plymouth, MI
Posts: 311
Trader Rating: 3 (100%+)

... and lets all remember that these "motor checkers" are not true dynamometers, so any information gained from them is speculative. The track is your best "dyno".
RandomFellow is offline   Reply With Quote

Similar Threads
Thread Thread Starter Forum Replies Last Post
24 Heures du Mans Mason Chat Lounge 42 06-18-2008 06:52 AM
Le Mans series pinky2252s Chat Lounge 1 03-15-2008 03:03 PM
Le Mans Bodies simba350 Australia Wanted to Buy 0 03-27-2007 05:19 AM
1/10 Le Mans Body simba350 Australia Wanted to Buy 0 04-27-2006 02:56 AM
Le Mans Bodies GTMilenko Electric On-Road 0 01-05-2003 03:50 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

All times are GMT -7. It is currently 10:22 PM.

Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net