I am trying to use a 3.7 Volt 1 Amp (so it's 3.7 Watts) Lithium Polymer battery to charge or at least trigger the charging symbol on an iPhone 5. I have charged the battery fully using the Lithium Polymer Battery charger. I plan on connecting the black and red wires on the battery with the black and red wires inside a lightning cable. Then, I will plug this lightning cable into the phone. I do not care how fast or how long it takes to charge the phone. I would just like to know if it will at least trigger the charging battery symbol on the iPhone. From what I heard, 2.5 Watts to 5 Watts with 1 Amp is enough to charge an iPhone 5, but I cannot find anywhere whether the iPhone detects this charging. I know my USB port in my older 2006 PC which only gives off 2.5 Volts can trigger it, so I believe a newer battery can easily do it. All help is appreciated.

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    I haven't tried that, but I would assume you'll need to deliver 5V for it to work properly. If you have a look inside those single cell power banks based on a 18650 battery, you'll notice that they have two switching regulators. One to step-down (buck) from 5V of a USB power adaptor to 3.7V and another to step-up (boost) from the 3.7V to the 5V, as that's the standard USB voltage.
    – Musskopf
    Commented Jan 18, 2016 at 23:02

1 Answer 1


It will not work. iPhones use USB and require 5 volts. They do have a margin of error and I have measured as low as 4.6 Volts being recognized, but 3.7 is too low.

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