Phone draw current low when using portable charger?

Short explanation:

When I charge my phone via a usb charger you plug into the power point, by measuring the output voltage and draw current, it shows around 5.2 volts 1.5 Amps. So the phone is drawing around 1.5 Amps.

When I used a hand cranked charger (portable charger) the output is 5.4 volts with .5 Amps draw current from the phone.

So I tested the portable charger (hand cranked) and it seems that I can get as much as 5.5 volts 3 Amps from it consistently. So the hand cranked charger works as it should!

From what I’m told, this is because the phone queries the charger and tells it how much draw current there should be. Unfortunately, the phone can’t communicate with the hand cranked charger so the draw current remains low at .5 Amps.

I was told to bridge the positive and negative terminals of my charger output cord with a 1000uf to 47000uf capacitor. But I’m not sure what this will do. I can’t seem to find the person who told me this so I’m asking does anyone know why this would work and if there are any other solutions to my problem?


Fast-charging Apple products has always been difficult. There are many ways to go about it and here’s just one method (it’s more of a saga):

You could build a custom cable with those parts inside of it using parts such as:

This is an android phone… It’s not fast charging!

My apologies, I had just assumed iPhone as it’s often more annoying.

The approach is similar, you’ll need to do some light research to find the best config for smart devices that require D+/D- to be configured in specific ways.

This is a protective measure as drawing more than 500mA on USB 2.0 can trigger issues. USB 3.0 extends this to 900mA, but both are less than what you are after. You can see the conundrum though, high power USB devices need to know what they are connected to.

As you have discovered, the devices will still charge. They’ll just be limited to a conservative rate to ensure that worst case scenario, everything upstream is fine/safe.

Thanks for replying, but is there any way around this? Can I build something in between to allow my android device to think it’s ok to bump up the amperage?

When charging with a plug in USB charger, the phone draws a steady 1.5 Amps.

This is a big sideways step: but what happens when you charge a LiPo battery bank - does it take full charge?

If so, that might be a nice workaround. LiPo battery packs are very efficient at collecting energy (charging) and you might be able to charge your battery pack while your phone and other devices are connected. If it works the way I hope it does, it’ll also mean that any extra energy (beyond what the connected devices are taking) is saved within the LiPo Battery Pack.

If you don’t have a battery pack to use then I’d be happy to collaborate with you to design an inline adaptor of sorts. If you do the homework and prototype/test a circuit, I’ll design/mill/populate the PCB for you. That way you’ll have an inline USB Male to Female board that could be used for this and other things.

And who knows, perhaps others would be thankful for the shared design!

Thanks for the reply. I’m going to experiment with something I found on the web. This is where you bridge the two data connections in a USB cable either a resistor or just a straight bridge. Apparently this tricks the phone into taking more charge.

If that fails I will take another look at this idea so thanks for the offer with help.

The fast discharge rate of a LiPo battery could be useful, but I’m looking for something for travelling and will be using other applications off a battery pack so it may end up extra weight in that case.

I’m still waiting on some USB cables to test my work around with.

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