Output Voltage is low

[dbens293]

Hi,
I recently ordered, received, and built a MintyBoost, but i am having a problem with it charging my USB devices. I tried connecting 2 D batteries in series as the input for the device, but it seems that the output voltage keeps dropping down below the 4.5 volt level which makes the device toggle back and forth between saying it's charging and not charging. I also tried connecting 4, 3.7 volt batteries all in parallel as the power supply. The open circuit voltage for the batteries is 4.2 volts, but i am still having the exact same problem as before with the output of the MintyBoost dropping too low. Has this been an issue before?
Thanks!

[adafruit_support_bill]

What are you trying to charge with it? Are you measuring the output at the MintyBoost, or at the other end of the charging cable?

[dbens293]

I am trying to charge a Zune HD, and I am measuring the voltage at the pins of the USB port that is soldered on the PCB.

[adafruit_support_bill]

If you post photos of the front & back of the board we can check your assembly. It is also sometimes the case that the device is trying to draw more than 500mA from the MintyBoost. There were no charging standards until a few year ago, and not all devices follow them. Some devices behave better if you short together the two center pins of the USP socket.