This summer, I decided to upgrade from my trusty old clamshell LG dumb cell phones — one that I use as my primary phone and a second that I keep in the car for emergencies — and join the two billion people on this planet who use smart phones. As a Mac guy since 1984 who has owned 25 Macs, there was no question that I'd go iPhone rather than Android. I'm also not made of money and live a very frugal life, so I wasn't about to pop for a new iPhone 6s. I bought two used/refurbed iPhones on eBay — a five-year-old iPhone 4 with 16gb of memory and a four-year-old iPhone 4s with 32gb — for $44 and $79 respectively. Both phones are in excellent cosmetic condition and work perfectly, but the batteries were predictably close to the end of their lifespans. According to CoconutBattery, they had 850 and 740 full charge cycles respectively and would charge only to about 75% capacity. I used another company's kit to replace the battery in the iPhone 4, and that procedure went without a hitch. I bought the ifixit battery kit with Liberation screws for the 4s. I could have opted for a cheap $5 battery for the 4s, but I felt more secure that I'd get a truly new battery from ifixit.
Battery replacement on the iPhone 4 was so easy that I anticipated no problems for the 4s. I did encounter a couple, however. After removing the two pentalobe screws on the bottom, the glass back plate wouldn't slide up to remove. I had to sort of push and pry to get it to release. Installation of the battery was easy and straightforward, but the provided Phillips screwdriver seemed too large to fit the battery screw heads. Luckily, I had a tiny jeweler's Phillips that did fit. Reassembly of the phone brought a second glitch. The new Liberation Phillips screws were shorter than the Pentalobes and wouldn't "catch" in the threads of the back plate. I ended up re-using the Pentalobe screws, which also didn't catch in the threads. They spin freely but don't fall out. The back plate must be misaligned, but it looks correct and fits very snugly, so I'm not going to worry about it. All in all, another success.
CoconutBattery confirmed that both new batteries were, in fact, new — with zero charge cycles. I did the recalibration procedure as suggested, draining the batteries down to 10% before a full charge, and they both provide full rated capacity of 1430mAh and perform flawlessly. Capable of only 3g, neither phone is a 4g speed demon, and they allow no upgradability — the iPhone 4 is topped out at iOS 7.1.2, and the iPhone 4s at iOS 9.3.5, but that's fine with me. I'm happy with both. Since I'm not likely to watch streaming movies or TV on them, their smaller size is especially pleasing. They should serve me well for a year or two (and inexpensively using PagePlus) before I get upgraditis and pop for a used iPhone 5c or 6s, which should be easily affordable by then. Owning, as I do, a 17-year-old Saab, a nine-year-old MacBook, and a five-year-old iMac (all of which are in great shape), I'm unconcerned about lagging behind the curve of the newest, shiny techno-toy. My two nearly "ancient" iPhones should serve my needs very nicely.