Default QI Charger which PSU ?

Hi

Didn't think of this before I bought it.. But I've just received a QI charger from Amazon.

Which charger do I used with it?
The one from my nexus 5 or the one from the nexus 7 2013?
Ideally I want to be able to charge either device.

The QI states 5v 1500ma input.

Also what's the best app to monitor the charging, time, input heat etc?

Thanks

Sent from my Nexus 7 (2013) KitKat 4.4.2