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I'm trying to power my Arduino Uno using a basic power bank (5V/2.1A Output), the Uno lights up for around 20 secs. and then stops taking power from the bank. What can be the issue? Am I making a huge mistake here? Further details: 1. The power bank has a LED that lights up during the charging process, it doesn't light up when I connect jt to Arduino though (but powers the Arduino for a short span, after which the Arduino goes off) 2. The power bank is 10,000 mAh, 5V/2.1 Amps, charges my cell phone normally.

Edit: As requested, adding a photo of the whole setup.enter image description here

Kv07
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  • Please tell more. Add the extra information to you question. Can you make a photo? How did you connect it? When you power the arduino uno with a usb plug that has 5v, then it should work. Perhaps the powerbank is the problem? – Jot Sep 04 '18 at 07:55
  • @Jot Added the details as requested. Also, the Arduino is working fine when connected to a cell phone charger. – Kv07 Sep 04 '18 at 08:34
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    Maybe the power drawn is too few, and the powerbank is shutting down. Try adding some load to the arduino (e.g. a 100-150 ohm resistor between +5V and GND) – frarugi87 Sep 04 '18 at 08:49
  • @frarugi87 Yeah, I suspect this too. I'll try your solution and update here. – Kv07 Sep 04 '18 at 08:51
  • @Kv07 just keep in mind that 100 ohm at 5V is 250mW, so a 1/4W of resistor is very borderline. If you have 1/4W resistors, maybe it is better to put two in parallel (for instance two 150 ohm in parallel will draw 65 mA, with a power rating of 150mW each) – frarugi87 Sep 04 '18 at 08:57
  • @frarugi87 No worries, I have a 1KOhm resistor. – Kv07 Sep 04 '18 at 08:58
  • @Kv07 1k resistor will cause a 5mA load; try putting them in parallel, but I think you'll need at least 10-20 in parallel to have a "good" load. In any case, adding and subtracting 1k resistors you can find the value of current you need to keep the power bank "up and running", if this is the problem – frarugi87 Sep 04 '18 at 09:01
  • 1kΩ does not draw enough current. Do you have a 5v relay (use the coil as a load). Powerbank: http://ambraneindia.com/product/p-1122 I read a number of reviews that say that it turns off when the phone is charged, and a apple watch can not be charged with it, because a apple watch draws not enough current. I can not find the specifications for the minimal charge current. – Jot Sep 04 '18 at 09:01
  • @Jot my apologies for not giving the spec sheet in the question itself. I think the minimal charge current is too high for the power bank. – Kv07 Sep 04 '18 at 10:27
  • @frarugi87 I only have 5 units of 1KOhm resistors and some basic sensors like Ultrasonic/DHT11/LM35 etc. Can we work out a makeshift arrangement? – Kv07 Sep 04 '18 at 10:28
  • Some power banks can be forced to keep on, by only consuming more current for short pulses. See https://arduino.stackexchange.com/questions/55193/keep-battery-pack-awake-and-run-motor-every-6-hrs . This would keep the powerbank on, but not use as much power, leading to a longer runtime. – Gerben Sep 04 '18 at 12:59
  • @Gerben The power supply shuts off after 2 good hours of supply in the other question, in my case, the power bank hardly supplies for 20secs. However, to my understanding, a current drawn less than the minimum operational current should shut the power bank in a short while, as in my case. I don't know what's going on in the other question though. – Kv07 Sep 04 '18 at 19:24
  • hi again 5x1k = 25mA, which is roughly the same current the arduino absorbs, so I think you do not have enough current pulled out of the powerbank. Maybe you can attach a USB port hub and recharge your mobile while powering the arduino... If this works then it was this problem, and we can try figuring out what is the best solution to keep it alive without mobile (e.g. modifying it, or using Gerben's solution to use short pulses to increase the average current...) – frarugi87 Sep 05 '18 at 07:56
  • Voila! Attaching another power absorber (my cell phone in this case) caused the power bank to supply current continuously to both the Uno and the Cell phone. Infact, I took output of the power bank and plugged it back into the input of the powerbank, even that worked! Thanks for your help. If you could write this as an answer, I'll mark it as the accepted answer. Cheers! – Kv07 Sep 05 '18 at 13:26

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