Seeking Long-Term Power Solution for Arduino Uno and SG90 Servos

Other Hardware Motors, Mechanics, Power and CNC
1

I'm working on a project with an Arduino Uno and two SG90 servo motors, and I need some advice on a long-term power solution.

Here's my current setup:

4x AA batteries for the two servos
9V battery for the Arduino

The problem is that the 9V battery runs out in just a few hours. My Arduino is only powering an LED, maintaining a constant current from 5V to an I/O pin, and sending out a servo PWM signal. I suspect the AA batteries will also run out soon.

I'm looking for a reliable, cost-effective, and rechargeable battery solution to power the Arduino and servos for a longer period. As a beginner in electronics, I'd appreciate any suggestions or guidance.

Thank you!

2

What does it look like in real numbers?

That's normal.

The SG90 is a Servo, not a servo motor rotating 360 degrees.

What is the load on the servo axle?

3

None
I only has to move, that's it. The load is a extremely light which requires a push of a finger, at the end. Its basically no load.

4

I hope it can be around at least 10 days without recharge.

5
  • Is AC power available ?
6

To estimate battery lifetime, first use your multimeter to measure the average current draw of your project, say in milliAmperes (mA).

The required battery capacity (which is part of the product description) is that number of mA multiplied by the number of hours (h) you want the thing to operate.

Example:

Alkaline AA batteries typically have capacity 2500 mAh.
if the project draws 250 mA, the battery lifetime is about 2500 mAh/250 mA, or about 10 h.

7

No, not in the position it is currently in.

8

I'd say li-ion is the way to go, as they can store a lot of charge, however they can cost $20. :thinking:

9

  • Can the power be turn OFF between servo changes ?

  • What is the time between servo changes ?

  • Do you have an RTC .

  • Best show us a schematic too.

10

So, do I need to just attach the multimeter in series with the arduino and the servos and measure their mean current draw and the search a battery for it?
Thanks

11

Correct. But keep in mind that manufacturers tend to overstate battery capacity, and it is reduced as the battery ages, so it is reasonable to overestimate the required battery capacity by a factor of 2.

12

Yeah, Lead -acid batteries online look cheap for their charge, but will they provide enough current for a long time is my doubt

13

Thanks!

14

No need to doubt, do the math using the battery capacity formula.

15

Yes, but I doubt the Servo requires much current at rest. It is at rest most of the time.

Its quite random actually, it just turns on a switch whenever it detects someone going inside the room, which I guess is random.

I am sorry, but I am still a beginner and have no idea what that is.

Yes, I will share in a moment.

Thanks.

16
  • Is it okay for the servo power supply to be turned OFF between detections ?
17

Yes, it is okay.

Thanks

18

How much longer?
8 hours, 8 days, 8 weeks?

19

I would prefer 10 days without recharge.

Thanks

20

those can provide a LOT of current, which you might need some day.
as for power storage, they can power an entire room for hours.
and you can charge them easily, no need for as much protection as a li-ion battery, just don't put too much current though there, or it might explode, I recommend 6A for charging.
1 lead-acid battery can provide 600A, for a few seconds.