USB

[steven c]

Can a USB device work off a 6 volt battery? I mounted one on my 78 Honda with a 6 volt battery but it would not charge the phone which charges at 5.5 volts. It works fine on 12 volts.


chemical properties of aluminium metal

[Zoom Zoom]

Probably not. Generally speaking these things are just transformers. X in = X out. In this case 12 vdc in = 5.5 vdc out. So 6vdc in would yield about 3 vdc out.

John Henry

edit: Thanks Wayne. I knew it was not really a transformer per se but I didn't know beyond that. I was trying to keep it easy to understand. Thanks for the explanation!

[Wayne Orwig]

Not transformers.
They are usually buck down converters. They use a switching transistor, storage inductor, a few caps to filter it, and a diode to catch the inductor kick.
Older versions use a Darlington pair for the transistor. They needed over about 1.4 volts, just to turn on. So 5 + 1.4, means you need 6.4 volts just to start.
But I have seen some that are LDO (low drop out voltage) with a good mosfet that operate down to near 5 volts.

Alternately, I got a small bag of cheap BOOST converters from China years back for a project. I took one of those and wired it up for a friend to run a 12 volt GPS from his model T 6 volt system. You could do that, boost the 6 to 12, then use a normal charger. Inefficient though, if that matters. It will likely need almost 10 watts in, just to get 5 watts out.

I would get a couple of cheap chargers and test them, I'll bet you find one that works just fine at 6 volts. It is going to depend on the chip used and the power transistor type.
 

[steven c]

I ended up getting a cheap back up battery kept the phone plugged into and I was good for the day.
 And thank you for the explanation now I no why it didn’t work for me.