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I have an encoder which I have been successfully using when powered from my a USB2.0 outlet on my laptop. I need to be able to run it whilst disconnected from the laptop and so tried powering it from a power bank. This is only intermittently powering the encoder with more noise in the returned signal when it was working.

The encoder requires between 4.75V and 5.25V the power bank supplies 5V

The encoder requires current of 0.07A the power bank provides up to 2.1A

The encoder is the MAXON EASY 16 https://www.maxongroup.com/medias/CMS_Downloads/DIVERSES/ENXEASY_EN.pdf Pg 19

The Power bank is: http://www.energizerpowerpacks.com/product_page.php?p_code=P0014&l=en

What is different between the usb port and the power bank? And how could I replicate the output of the usb port without having to connect to a laptop?

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  • \$\begingroup\$ The powerbank is probably using a single lithium battery with a very poor step-up converter. Try it with a 5 V USB phone charger and if that's OK then get a better battery pack. The datasheet gives no voltage ripple specification \$\endgroup\$
    – Transistor
    Commented Jul 24, 2019 at 18:30
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    \$\begingroup\$ There should be no difference. However, you do have a different connector - perhaps this is gone loose and creating problems. Also, if you are reading the outputs on some other device, then do confirm that the GND points are tied together. \$\endgroup\$ Commented Jul 24, 2019 at 18:46
  • \$\begingroup\$ This question is off topic, however you probably have two issues: First a cheap powerbank will have a noisy DC/DC converter which can interfere with radio or audio circuits, next many shut themselves down when too lightly loaded. At light load currents you'd probably do better using say 5 or 6 AA cells and a quiet linear regulator with a physical off switch. \$\endgroup\$ Commented Jul 24, 2019 at 19:32
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    \$\begingroup\$ The powerbank is in all probability shutting down due to you NOT drawing sufficient current. The data sheet says your encoder requires only 22mA typical current. You could simply include a resistor across the output to increase the current ...wasteful, but may be effective. Many of the powerbanks do shutdown if lightly loaded. \$\endgroup\$ Commented Jul 24, 2019 at 19:34
  • \$\begingroup\$ This question is a duplicate of many other similar ones, e.g. electronics.stackexchange.com/a/286539/117785 electronics.stackexchange.com/q/270337/117785 \$\endgroup\$ Commented Jul 25, 2019 at 1:34

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The product page for the power bank says that it guarantees against short circuit, and over-charging for your portable battery and devices.

Opened up the user manual and the third line under Safety Instructions states once the product is fully charged, your power pack automatically shuts off to save power.

My guess is that this is messing with your desired operation. Your laptop is outputting a steady 5 V and doesn't care about overcharging, whereas the power bank is treating your encoder like a phone and so it shuts down intermittently.

I suppose a solution would be to determine what the power bank uses as a queue to shut off and circumvent that or buy a different power bank that doesn't shut down.


EDIT: I found the following on the Arduino Stack exchange: Power bank turns off spontaneously.

It agrees with my thought but also adds that a possible reason is that your load is too small. You could try putting an additional load in parallel with your encoder to trick the power bank.

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