Question Qualcomm Quick charging

[JMB1911]

When quick charging is the voltage supposed to stay a constant 9V or should it step down to 5V once the device is fully charged?

I've been testing some chargers / battery packs using a USB volt meter and a Galaxy Note 4 and I've notice when in quick charge mode it's a constant 9V even when the battery is fully charged. If I turn off fast charging on the Note 4 it charges at 5V.

 

[shabby]

The output wattage should lower near the end, if the voltage is staying the same then the amperage must be changing.

 

[agent00f]

When quick charging is the voltage supposed to stay a constant 9V or should it step down to 5V once the device is fully charged?

I've been testing some chargers / battery packs using a USB volt meter and a Galaxy Note 4 and I've notice when in quick charge mode it's a constant 9V even when the battery is fully charged. If I turn off fast charging on the Note 4 it charges at 5V.

The voltage going to the battery itself will necessary decrease unless you're of the mind to blow it up. Li-on are generally charged w/ cc/cv strategy; the "quick charge" just allows more voltage during the cc stage.