Is there a way to make iPad stay tethered to iPhone even when iPhone is locked?

Ok, the iphone and Ipad both turn their wifi antanae on for 90 seconds when you start up the personal hotspot and become "discoverable" to the other. If you're using your phone as the hotspot, then I recommend you turn OFF the autoscreen lock feature, if the screen autolocks then the wifi hotspot turns off, if you set the phone to autolock never then manually lock your screen the hotspot will not die since the autolock never kicked in and turned the wifi antanae off.

To be clear, autolock cuts off the screen AND the wifi, manual lock just cuts off the screen. I don't know if that's a bug or not, but it's not documented anywhere I've seen.

Now, if you're using the IPAD as the hotspot to the phone, when the phone screen goes off, the ipad will keep broadcasting for another 90 seconds and if nothing links up, it too will turn off the antanae to save power. HOWEVER there is a little known feature that neither the ipad nor the iphone will turn off the wifi IF they are drawing power. What this means is that if you happen to own a mophie or other external battery case for your phone you can turn on the hotspot on the Ipad, turn the mophie on, then connect the phone to the ipad then let the phone sleep. This will keep your phone tethered to the ipad hotspot indefinitely.

I suppose this could work in reverse but I don't see many Ipad battery packs so it's really only practical for people using the ipad as the hotspot for their phone.