Battery life draining more on previous phone?

[Qwebs]

About a week ago, a family member took me to Verizon to get a new phone. My previous phone was a Droid Maxx 2, which came out in 2015. I got a new Motorola Moto Z4 and kept my previous number. However, I noticed that after my old Maxx 2 had been sitting idle for a few days, the battery has drained DRAMATICALLY. It was at 5% when I turned it on, it's been 30-45 minutes now and it is only at 28% with 1 hour and 7 minutes left to charge. Granted, the phone's battery had been acting up before this, but never this bad. It would shut itself off at 20... sometimes even 30 or 35 percent. It would say "0% - Power Off." When I turned it back on, it would turn itself off within a few seconds of booting up. This isn't that much of a problem considering I have a new phone now, but I wanted to back up some of my old pictures. Is this drastic battery drainage common with old phones after getting a new one with the same number, or was me getting a new phone just in time (I figure it could be either of the two, though I'm leaning towards the latter since the phone is about 4 years old at this point).

 

[B. Diddy]

That sounds pretty typical of a failing battery. Leave it plugged into a wall outlet overnight, and then back up any important data from the phone before things completely fail.