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USB battery + 12V DC charger

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Newbie level 2
May 22, 2015
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Hello everyone

I could like to ask a question: I have an USB battery with 5V output. How I boost from 5V to 12V with a charger?
I have also have a DC to DC Boost Buck Converter from 5V to 12V, but it is not working!
With a transformer from 220AC-to-5V DC it is working: 5V input and 12V output. But with battery does not working...

Please help with this matter.

Thank you
Aris Kyranas

We may sugest, that your USB battery gives you 5V 1A power. After step-up converion we can expect for 300mA max and 200mA in real conditions. So, it should work, but don't expect high efficency because USB battery already has 3.2-4.2 -> 5V step up converter.

The real limitations of boost converters is not just the power relationships for VI in vs out but the requirements for impedance ratio being much lower than load than simply /N²
, where N is the voltage boost ratio.

this is because due to input load regulation requirements to keep USB charger within 10% , its source impedance must be 1/10 of expected transformed impedance levels . Or with 1% load regulation must be 1% =Rs/Rload

from testing your 5V source for load regulation using any reasonable load R measure drop in V for rise in current and this is your ESR. Then for Good regulation using 5% criteria and voltage gain of 12/5=2.4 your load impedance cannot be less than ESR(5v)*1/5%* 2.4²=ESR(5v) * 115

So what are your measurements?

Hello all

I have another experiment witch I believe it is a solution for DC-DC boost converter.
I have 2 5V USB batteries and I connect in series, so I have a 10V dc. The module in input is 10V and in the output is 12-13V, so I connect the load I prefer. The solution is not the best, but it works!

Thank you for your attention
Aris Kyranas

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