I am trying to use a power bank to power a project which consumes 700mA. But the power bank only delivers about 100mA.

But when I connect my phone to it, it easily delivers 1.5A to the phone.

Power Bank: http://ambraneindia.com/product/p-1310-premium

I've tried
1. shorting the data pins
2. putting a resistor on the data pins

What am I missing here? Is there some kind of handshake involved? If yes, how can I bypass it?

Sorry if this is a stupid question, but I'm new to this.

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    \$\begingroup\$ Please learn the difference between mA and mAh. That "h" is important, and putting it in the wrong place will lead to all kinds of confusion. Hint: all of the places you've used it are wrong. \$\endgroup\$ – JRE Jun 29 '17 at 7:31
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    \$\begingroup\$ There is no such thing as "a project which consumes 5V 400-700mah". What does that mean? mAh is the capacity of a battery or power bank. So a power bank cannot deliver "only about 100-150mAh". Also, which data pins?! \$\endgroup\$ – nickagian Jun 29 '17 at 7:35
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    \$\begingroup\$ Similar? electronics.stackexchange.com/questions/121366/… \$\endgroup\$ – Sachin Jun 29 '17 at 7:45
  • \$\begingroup\$ Extremely sorry, but I've made the changes. By data pins, I mean the middle 2 pins of USB. I've spliced a USB charging cable from android phone to supply power. \$\endgroup\$ – mgtech Jun 29 '17 at 8:03

First of all, there is a difference between mAh and mA.

mAh is how many milliamps can be supplied over the course of an hour. For example, if your power bank was 1000mAh, then it could supply 1A for 1 hour, or 500mA for 2 hours, 250mA for 4 hours (so on and so forth). mA should be pretty self explanatory if you are using electronics.

I think you will need to check the specs of your project again, do you mean to say your project should consume 400-700mA? I am pretty sure you meant to say when your project was powered by the power bank, the power bank only delivered 150mA?

If it easily delivers 1.5A when your phone is connected, that shows it is not the power bank. It may well be your project that is not working correctly, or it quite simply doesn't require the power you seem to think.

I have had to make a few assumptions about your question in this answer, so if I have anything wrong, please write a comment, but I think what you really need to do is double check the specs on everything and provide the correct units as this will help make it slightly less confusing!

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  • \$\begingroup\$ I'm very sorry about the confusion. I meant 'ma' instead of 'mah' & I've made the changes. \$\endgroup\$ – mgtech Jun 29 '17 at 7:57
  • \$\begingroup\$ The project uses anywhere between 400-700ma. I've been using the project on a 2A USB Wall charger (came with a moto phone) & it works perfectly fine. But when connect it to power bank, it only works for few seconds. I've measured the current using a multimeter. \$\endgroup\$ – mgtech Jun 29 '17 at 8:00
  • \$\begingroup\$ Mind if I ask what your project is and how you have built it? \$\endgroup\$ – MCG Jun 29 '17 at 8:13
  • \$\begingroup\$ Sure. Its an android tablet (nexus 7 2013). The micro-usb port is used to connect mouse via OTG (since touch screen is broken). The battery went bad. So it has been removed & 5V is supplied to the battery protection circuit (the small PCB stuck to the battery). It works fine when connected to 2A wall charger. \$\endgroup\$ – mgtech Jun 29 '17 at 8:20
  • \$\begingroup\$ I read somewhere for some android devices you can stick a 200 ohm resistor across the D+ and D- pins.... give that a shot \$\endgroup\$ – MCG Jun 29 '17 at 8:43

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