Dear HNers,I am one of those die-hard iPhone SE users (the original model from 2016), and from reading related posts on this forum, I know there are many of you out there too :-)Sadly my battery life had been getting increasingly worse, to the point where a full charge would only last around half a day (when using my phone actively), or otherwise barely make it to night time (when using my phone scarcely).I think this has been compounded by my working-from-home, since my cellular signal strength at our house isn't as good as it was back at the office (I began noticing that my phone, whilst idling, was connected to 4G with very poor signal - around 1 or 2 "dots" out of 5 - but whenever I made a call, it changed over to 3G where the signal strength was 5/5).Thus I figured I'd try permanently disabling 4G on my iPhone, so that even whilst it is idling (or basically whilst I'm using it, but not on a call), it will stay connected using 3G.To do this, I went to: Settings > Cellular > Cellular Data Options > Enable 4G (and set this to "Off").My iPhone now uses 3G only, and my battery life has literally doubled (it now lasts on average 2 days if I use my phone scarcely - but even with active use, the battery is sitting at around 40% to 50% by the time I go to bed).Of course this will depend on how close you are to a 4G tower as well as the structure of your home (and therefore how good/poor your signal strength is).In my case, my 4G signal wasn't that great at all, but my 3G signal is fantastic throughout my house.This new-found battery-life has added a couple more years of usage to my little iPhone - which I am delighted about.Just figured I'd share this here in case it helps one of you too :-)