Use iPhone without battery installed

Hello, I am interested in finding a way to get an iPhone to turn on without a battery installed. The reason I am looking to do this is because I have an iPhone collection which I plan on keeping for many many years. I have most of the iPhone models in my collection and some of them already have failing batteries. I have tried booting an iPhone without a battery while connected to a charger and the apple logo appears for around 4 seconds and the device restarts and keeps doing that. In the future replacement batteries for these phones will slowly become impossible to find and that would mean I would have a pile of dead iPhones.

Thanks.