I will give this a try. I have about a dozen mobile phones just sitting around doing nothing. I tried using some of those apps that turned out to be scams to try to collect some sort of coin. I have no issue leaving them run all day.
I also run a mining rig, but if there is some light app that will mine this that I could run on that as well, it could be a dual mining option.
If the mobile is to old - you can not download the app. I tried with a phone with Android 4.0 and it does not work. But with new model it work. My phone is 18 mounth old and it work. You can also mine it with a computer with a program that act as a phone - see here - https://steemit.com/cryptocurrency/@minimining/electroneum-mining-on-a-computer-via-app. Everything is working very good.