Arthur Ravenscroft wrote:
On Thursday, 9 July 2020 18:28:11 UTC+1, Arthur Ravenscroft wrote:
Hi.
Can I use
https://www.rapidonline.com/gp-batte...-white-18-0522

via

https://www.rapidonline.com/bkl-1008...raight-54-6230

to power a 6 volt dc motor?

Cheers.

I should change tack and go with a power adapter, I think.

Have you measured the consumption yet ?
While sawing the coffee stir stick.

Test Source -----------X Multimeter Amps X--------X motor X---+
|
Test Source --------------------------------------------------+

It sounds like you're using a different motor now.
Have a link to the information for that motor ?

This is an example of some datapoints for a DC motor.

Specifications

Free Speed:100 rpm
Stall Torque:8.6 in-lbs
Stall Current:2.6A
Free Current:0.18A

7.2 volts

Here is another motor, where they tried their hand at guesstimates,
versus someone finding the actual table values for it.

https://electronics.stackexchange.co...n-for-dc-motor

If you have a wall adapter, you have to think carefully about the
overcurrent detection and shutdown. When the motor starts from
zero speed, for a very short moment, it draws stall current. As
the saw blade begins to accelerate (even a little bit), the
current starts to drop towards the more normal values.

If I don't know anything about a motor, I check the nameplate.
If the nameplate says "one amp, running current", then my guess
(without justification) is 10X to 20X that value.

To run a 0.2A motor, I might want a 2A adapter. The above
table example makes 3A a safer bet.

Now, if you happened to use a 2A wall adapter, are sawing a
coffee stir stick, the blade jams, then the current leaps
up to 2.6A, which is more than the 2A adapter provides, and it
shuts off the output. So sometimes, a designer might be
taking advantage of such a characteristic on purpose.

On things like electric screwdrivers, they err in the "we won't
quit" direction, choosing to let the motor burn, rather than
annoy the user by not driving that screw all the way in.

But generally, you want a power source which covers a decent
part of the operating range, for fewer surprises.

*******

Did you know that even stinking light bulbs are a challenge ?

I think it's pretty funny, when I connect a light bulb to a
wall adapter, and the wall adapter shuts off. This happens because
a light bulb draws about double the power when it is cold, and
if you connect a 1A light bulb to a 1A adapter, the adapter
promptly shuts off. The light bulb draws 2A when cold. To
run a 1A incandescent light bulb then, you buy a 2A adapter
and then the bulb lights and the adapter stays on.

And this is why we need to discuss stall current, and behaviors
possible when the load is first switched on. This is part of
the reason why "inductive loads are a pest". And why it's an
achievement when a Tesla Power Wall (two of them power an entire
house), are able to withstand a 2HP motor on the air handler
of the heating system, without tripping out. A lot of other
powering options (that small Honda emergency generator you've
got), they hate firing up big motors.

Now, if you ignore my suggestion, at least you'll understand
why the motor is refusing to spin on a too-small wall adapter.

If the datasheet for the motor has all the necessary values,
then you don't need to be doing guesstimates or making current
flow measurements.

Paul