Motor power usage tests...

Namuna · #1 02-06-2003, 01:10 AM

I pulled out my digital multimeter (again) for some more indepth testing...This time for specific current draw from different Motors. Here are the results (I'll leave the conclusions for all of you to come up with, but these numbers are 'interesting' indeed)

The voltage output is constant for all motors (basically the same as the rating of the car battery)

The Test Setup:
Taking you 56k'ers into consideration, I put all the pitures into the Gallery (so check it all out there)
Took out my Digital MultiMeter , Helping Hands and used a small length of Wire. The last time I took out my DMM I ran the mA tests with no load whatsoever (no motor), this time we'll find out what the deal is with the motors.

In order to properly test the current drain, the DMM has to be setup as part of the current flow...Which gets TRICKY doing it yourself (thank gawd for the helping hands!).

http://tinyrc.com/gallery/motortests/aaa
I took the black lead (from DMM, with alligator clip attachment) and locked it down on the metal plate that the motor endbell rest on, then using the wire with the ends stripped I attached 1 end to the metal in the chassis that the motor rests on, then the other end wraps around the motor (while being held by the helping hand clip).

http://tinyrc.com/gallery/motortests/aae
With that rigged up, the only thing left to do is touch the red lead (from the DMM) to the metal on the endbell (of the motor) and press the forward/reverse button to start the current flow and read the results.

Cars Tested: (Both fully charged before tested)
Stock Bit Char-G
Stock ZipZaps

Motors Tested:

1) ZipZaps 1.6 (Performance)
2) ZipZaps 2.35 (NOS)
3) ZipZaps 2.15 (Turbo)
4) Clone 2.8
5) Tomy 1.0
6) Tomy 2.2
7) Tomy 2.6
8) TinyRC R-Spec
9) TinyRC 3.8

Results

The R-Spec and 3.8 motors both had problems pulling enough juice to run properly in the ZipZaps, the numbers given were when the PCB would intermittently give the needed amount

*MicroHP = 1/1,000,000th of a Horsepower

BenCloned · #2 02-06-2003, 10:00 AM

Awesome, Namuna! I've been begging for actual testing. Great news for R-Spec fans.

The one you left out was the 1.6, which is supposed to be high torque.

And the new ones on the Tiny RC site.

hogjowlz · #3 02-06-2003, 10:09 AM

1.6 = weak not worth mentioning.

kwikbb · #4 02-06-2003, 10:19 AM

Quote:

Originally posted by hogjowlz
1.6 = weak not worth mentioning.

I for one don't feel this way and would love to see the results, I'd be curious to see effects on draw caused by the higher torque... if that is a consideration at all. I was shocked to see that the draw on 2.2 was 50ma higher than the 2.6

.
Sweet job Namuna!

BenCloned · #5 02-06-2003, 10:25 AM

Now if we could only figure out how to build a tiny dyno...

We could get the RWH and RWT numbers!

Namuna · #6 02-06-2003, 11:32 AM

Quote:

Originally posted by kwikbb
...I was shocked to see that the draw on 2.2 was 50ma higher than the 2.6

Yup, people thought I was crazy before when I'd say my 2.6 motor would run for much longer than my 2.2 motor...Now I have PROOF of why!

Alright, I'm updating (with pictures) my original post. So if it looks different next time you come back to this thread...That's why.

BabyKiller · #7 02-06-2003, 12:09 PM

so to use a r-spec to fullest with mods u need a 150mah battery?

spikeymike218 · #8 02-06-2003, 12:17 PM

Quote:

Originally posted by hogjowlz
1.6 = weak not worth mentioning.

...well 1.0 is weak also, but he mentioned it...also 3.0 was not mentioned and that motor is not weak. maybe he didn't mention it because he didn't have a 1.6 or 3.0 on hand. just because a motor isn't mentioned doesn't mean its weak...

Namuna · #9 02-06-2003, 12:27 PM

Quote:

Originally posted by spikeymike218
Maybe he didn't mention it because he didn't have a 1.6 or 3.0 on hand. just because a motor isn't mentioned doesn't mean its weak...

You are correct, I can ONLY test motors I have...I don't have a 1.6 or 3.0, nor anything else except for what I tested.

funkymonkey · #10 02-06-2003, 12:35 PM

Namuna, i'm assuming these current draw figures are for 'no load'? If that is the case the figures may be misleading - you need to test them with load on. Seeing as you can't test 'em racing round the track I suppose the test figure is 'maximum load' or stall current - ie hold the motor so its stalled and check current draw then.

This would surely be a better indication of motor strength?

Namuna · #11 02-06-2003, 12:59 PM

Your assumption is correct funkymonkey, the motors ran free with no load.

You have a point about testing for 'strength' and i'll adjust my testbed and re-adjust for max load/stall current...I'd imagine the ZZ motors would have a better outlook under such tests.

But, I do believe that the numbers I did find are significant in that they can give, at least, a general 'Efficiency' of the motors.

Spanky · #12 02-06-2003, 02:19 PM

excellent tests.

i would like to see tests between cars such as the shen, bit, prescious, thunderbolt, etc. to see if they all draw electricity the same way, or if somehow their deisgn is preventing higher or lower charges/voltage going to motor.

kwikbb · #13 02-06-2003, 02:38 PM

Namuna;
Great pics man! I have you to owe for my 'continuing education' in the field of electronics

Thanks,
B

BenCloned · #14 02-06-2003, 02:53 PM

Quote:

Originally posted by BabyKiller
so to use a r-spec to fullest with mods u need a 150mah battery?

Not exactly. If you want run-time, the higher mah rating is what you want. If you're looking for performance, NiCAD's pump out more current.

It's the difference between capacity (mah) and current (wattage).

Kinda like the "Cold Cranking Amps" rating on a car battery. It says nothing about how long the battery will last, but it tells a great deal about power output.

Namuna · #15 02-06-2003, 03:36 PM

Quote:

Originally posted by BenCloned
It's the difference between capacity (mah) and current (wattage).
[/b]

Just a little correction...

Capacity = mAH
Current = Amperage (Or for our uses, milliamps)
Wattage = Voltage X Amperage

A good thing to keep in mind with all this fun stuff is Ohm's Law (V=IxR), and a delightful thing to help keep it simple is the 'magic' triangle for Ohm's Law.