how do I measure a motor?

N

Noidea

New Member
Dear All,

On the weekend, I purchased an old r/c car and took it too bits, taking it back to basics, the engine, a servo/possible stepper motor and battery compartment. I want to connect a picaxe with a couple of mods to it and want to;

[a] find out what sort of motor it is and the required voltage
figure out if the steering uses a stepper or a servo
[c] figure out how to connect the damn thing.

Any help and all suggestions would be appreciated.

(oo) NoIdea (oo)
 
E

eclectic

Moderator
Well the first suggestion is
more information please. :)

1. Datasheet / description / component labels.

2. Multimeter resistance-readings.

3. High-quality photographs.

and so on....

e
 
B

boriz

Senior Member
Motor voltage = Battery voltage. No battery? Check with manufacturer / retailer.

Very unlikely the steering uses a stepper. Some cheap RC cars have an electromagnetic solenoid type steering with only three positions – left, right, centre. Otherwise probably a servo.

Connecting a servo and a motor to a Picaxe is easy. Read the manuals.

Pictures would help.
 
B

BeanieBots

Moderator
I'll put money on it, no stepper motors.
What was the origianl battery voltage? That's your motor voltage.

In general there is no way to determine the factory desinged voltage of a motor other than speak with the designer or read the markings on the side of it and obtain the datasheet. Applying a controlled low voltage to determine the volts/rpm to give a 'sensible' speed for your estimate of the bearing limits is the best you can hope for.
A 'look' at the winding gauge and a guestimate of the number of turns will give you a guestimate of the current rating.
Overall size and strength of magnets will give a guestimate of power rating but that assumes you have a good 'catalogue' of experience to compare to.

Is the steering system a servo?
Did it have proportional steering originally or was it a cheap hard-left / hard-right type steering. Proportional will be a servo. The other will either be another basic motor or possibly a solenoid.

As suggested by eclectic, submit some photos and we can guess for you.
 
M

manuka

Senior Member
Many older R/C cars used NiCd battery packs giving 6 x 1.2V =7.2V for small vehicles, or 8 x 1.2V = 9.6V for larger.
 
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B

BeanieBots

Moderator
and cheap ones use 2XAA = 3v. Modern ones use single Lipo = 3.6v.
I've got a 1XNiCd (1.2v) IR controlled car.
I've also got one which uses an 80A 9.6v LiPo.
It's 100% guesswork.
 
A

Andrew Cowan

Senior Member
manuka said:
Many older R/C cars used NiCd battery packs giving 6 x 1.2V =7.6V for small vehicles
Click to expand...
I make 6x1.2 = 7.2v.

From what the OP says, it sounds like a a 'toy car', rather than a hobby car.

I would make the following guesses:
- Steering = a solenoid arrangement, as boriz and Bb say.
- Motor = something small - possibly a 370 type motor. Most hobby cars mostly use 540 motors.
- Battery = 6 or 8 AA cells, so 9 or 12v

Lets see some photos!

A

Bb - mine's bigger than yours - 11.1v @100A ;)
 
D

Dippy

Moderator
Mine's even bigger Andrew. That's a mere pip-squeak.

I've got a couple from an old Crawler. But if you don't know anything about proper rockets or haven't got access to Google then you won't know what it is.
 
T

Taniwha

Senior Member
Well I can't go big on motors but can i sell anyone a 3,000ah 2 volt cell? (and no that is not a mistake, we sell 3,000ah Sealed Lead Acid cells)
 
B

BeanieBots

Moderator
Never mind Andrew, by the time my driving liscence has expired, you will have completed your first few years in employment and will be able to afford a Tesla.
0 -60mph in 4.7S, 160mph, 200 mile range.
Not bad for a milk-float!
 
W

westaust55

Moderator
I’m sure Andrew would prefer a Bugatti Veyron with a top speed of 407kph.

He could then spend his time in employment to pay it off and keep it fuelled. :rolleyes:

A motoring writer out for a test drive in a AUD$475k Ferrari California near Toodyay here in West Aust last week got caught by the local constabulary for driving at 231km/h in a lesser car. On a winding country road as well! The car was impounded for 7 days under our new traffic laws.
 
B

BeanieBots

Moderator
The battery in the Veyron is a tiddly little 12v 110Ahr. Hardly a comparison!
The 1000 bhp engine might have a use for running the generator to charge a few Teslas though.
 
R

Rickharris

Senior Member
BeanieBots said:
I've got a real one too.
300v @ 90kW. (36*6cell*7.2Ahr) Gives about 2miles at 30mph with four passengers.
Click to expand...

I can't get into this "mines bigger than yours! " :)

... but we get, (got), an average of 22MPH over 4 hours with a peak speed of 28 MPH 1 driver and had to stop every 40 mins or so to changes the driver, (speed is so stressful).

All this on 4 70 Ah 12 volt standard car batteries.
 
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