I've had a cell phone of some type or another since the mid '90s. I can't say I've ever had one of my vehicles kill a cell phone.
I can understand one scenario where it might happen, and that's if the voltage regulator goes bad. If it sticks "on" the alternator may go wild and send upwards of 20 volts through the system. If this happens, it sure won't do cell-phone chargers any good and just might send wild voltage into the cell-phone itself. I suppose a bad battery may cause it too, if the battery gets an internal short while the vehicle is running the alternator will try to feed that pig. This will show itself the next time you try to start, the shorted cell will drain the battery so much that starting will be next to impossible and if you connect a charger to get started expect the indicator to peg at the top of the range. While running, the alternator was feeding wild current through the system, maybe too much for cell phones that were plugged in at the time and--- doggone good thing the truck didn't burn to the ground if that happens, too. Though usually a fusible link will stop proceedings before that happens.