Usb battery bank help and questions ?

well i want to add like a battery pack instead of the 9 volt batteries i have now and this a ruff model i made today, but i will make a better case but back to my question is would this work?  or do you recommend something else it has to be rechargeable,  

Picture of Usb battery bank help and questions ?
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iceng5 years ago
To do what ?
Run an RC car or a copter or a keyboard ?

How much current then ?

imnew59585 (author)  iceng5 years ago
a cell phone charger, just a back up usb battery bank
imnew59585 (author)  imnew595855 years ago
so 5volts
USB is 5vdc capable of  up to 1 amp.

Cell Phone batteries are 3.3v to 7v what is yours ?

Now what ?
imnew59585 (author)  iceng5 years ago
3.8vdc 1730mah 6.57whr
See the circuit uses two 1N5819 Schottky diodes ( 14¢ ) in series to
drop the 5V USB supply on the left side by 1.2 volts resulting
in 3.8 volts on the right for your battery.

The 47 ohm resistor limits the charging current to 80 ma.

If you need more current use a lower resistance.

I didn't use a 317 regulator because it needs a 2 volt difference to
regulate and that would make it impossible to output 3.8 volts..

Don't use another diode because these were selected to provide
the necessary voltage drop...

USB DiodeReg.jpg