Which power adapters to replace these 2 battery packs in roller curtain project?

I have this project. I drew it by hand because I couldnt find a couple of parts in fritzing and eagle is much less sophisticated in terms of end user parts which would have it even more of a hassle (i think).

The parts are:

  1. Arduino Uno
  2. Esplora Wifi shield (generic)
  3. L298N motor driver module
  4. Breadboard
  5. 6xAA battery pack (energizers)
  6. 20kmah rechargeable battery pack for phone charging. (its got about 9 18650s inside)
  7. 30 rpm low geared motor for roller curtain (tested and used quite frequently)

The thing is I dont want to be connecting the AA batteries and the battery pack to each module in order to be able to use it. I want to plug it into a wall socket.

A. I have a 5V & 9V 1A which I can use for the Uno/Wifi Shield.

B. I have a 9V/1A and even a 9V/3A I could use for the motor.

C. The main issue is the energy waste. I think I remember a bit about the L298N pulling power from the source (6xAA) battery pack until it drained it dead which is why I always leave 1 battery off until I plan to use it.

How much power are we talking about getting wasted by the L298N? Im guessing the one from the Uno/Shield would be insignificant.

Where do you think the lost energy actually goes? It goes to heat your home! Is a little electricity power converted into heat costing more than that same amount of energy you currently use to heat your home? Usually not.


Yeah but how would I calculate it? Would it be 9V * 2A = 18W? No, that would be the max, but when it's just sitting there not being used the amps flowing would be much less no?

Measure the quiescent current draw with a meter and multiply by 9V?

The reduction gearbox on the motor may be enough friction to prevent back-driving if the
power is removed - have you tried this?

If not then perhaps a worm-gear drive would have been a better choice as they don't

Ok just double checking. i have a klein 1000. If i want to measure current draw, I can interrupt the (-) cable from my power source (adapter) to my L298N Gnd connection with the meter set to uA, oh wait, but the max read on this meter i think is from 400-2000uA which is 2mA. Ok i need my other meter with 10A max.

But I can interrupt the (-) line right? I mean just as well as the (+). Its just that given my current setup, its easier for me to interrupt the (-) line.

ok I set my meter to 10A setting on DC current and with the motor at idle it reads 0.04 and when the motor runs it reads 0.08. Im guessing those are not A, cause that would mean it draws 40mA idle and 80mA on operation? I dont know about that, 80mA for a motor seems too little. Its a 12VDC 10 or 30rpm motor, I cant remember which:

oh ok, its the 10rpm…so maybe it is 80mA.

Can anyone help me with the calculation?

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