Man, that Route 9 story gave me chills because I did the exact same thing last year with a dead phone in a rural area. It's crazy how we never think about this stuff until we're actually stuck. Testing your old phones for six months of battery life is super smart though, most people would've just grabbed whichever one looked tougher and called it a day. And yeah, that barrel plug on the Nokia is a real pain, good luck finding a car charger for that thing these days. I totally get the rabbit hole feeling too, you start with one simple backup idea and end up researching SIM cards and battery tech for a week straight.

Mix in smaller batches when it's that hot, or keep the pile shaded and hit it with a wet tarp. Also, set a timer on your phone for 20 minutes max, that stuff sets fast in Phoenix. Been there, wasted a whole afternoon chipping it out too.