Author Options:

USB 5v step up to 12v? Answered

Is there any such thing as a device that will step up 5v from usb and convert it to something else like 12v? I say this because I have a solar usb charger that charges a 2600 mah battery and outputs 5 v at 800mah to usb. i wanted to step it up so it could be used for other things.




3 years ago

I have the same question, but "HOW" to do it. Is their a product anyone knows about? I'm looking at 20w solar charger for my usb devices, but say if I got stranded, I would love to trickle charge a car battery.

Need from usb, to car battery connector.


6 years ago

Yes,  and What is a solar usb charger ?


There are a bunch on ebay/dealextreme - a small (200mA) panel trickle charges a LiPo battery in a housing with a charge controller and usb port/regulation -- acts as a spare battery and the solar is a nice touch.

As for stepping up that 5v to 12v - yes, it can be done, but as always, you give up amperage to gain voltage.

Say your battery can handle 5v 500mA (about 2.5 watts)
converted to 12 volts that's (cross multiply) 208mA of current.
You can never magic up more power, only the form that the energy is presented.

Thanks for info on that :-)

Your absolutely correct  ! !
There is no way to expect more energy when stepping up voltage
the current will be proportionally less and there will also be a conversion
efficiency loss too.

Keep in mind that when you step up the voltage the amount of available current drops. So the solar charger's battery pack is only offering 5V at say 800mA thats a total of 4 watts. If the step up converter is 100% efficient (and they never are) then stepping up to 12V will only give you about 300mA to work with. Don't know what your hoping to use it for but i doubt there is much you can do with 12V @ less than 300mA. But the 800mAh rating of the batteries don't translate over to the available amperage. The available amperage will be limited by what the converter can handle. But needless to say the battery will not last very long under those conditions.

Think about it like this. Lets say the battery will work for an hour being run through a step up converter but it takes 14 hours for the solar panel to charge the battery. Is it really worth it?