The problem with OTG and simultanous charging is that you'll probably need a custom kernel supporting this.
Because if you use OTG (or a data cable respectively), the phone will only charge with 500 mA max. - this might not be enough to charge your phone while using power-consuming apps (navigation, games,...). If you want the phone to charge faster/draw more current, you'll need to short-circuit the data leads - but then you can't use OTG/data. Tricky...
Moto G (XT1032) - rooted & xposed stock 4.4.4 / Nexus 7 - rooted stock 4.4.4