I used to mess about with eBay batteries, became more and more difficult - to find decent batteries, and with them being glued in, "water resistant" needing to dismantle practically the entire phone, replace the back casing etc.
Now I just buy a new phone every year/18 months - I'm a fan of Motorola "G" phones - typically buy a refurb (in reality new return or grey import) on eBay for around £140 and sell the old one for around £80.
I do absolutely hammer my phones and think that just over £1/week is a bargain for a reliable up to date mid range smartphone with outstanding battery life.
An S5 is no longer supported by Samsung in terms of updates to the operating system, security etc so unless your an old codger who just uses it a a telephone then you should consider something a bit newer.
cdbe, I
am an old codger (as you so respectfully put it - ha, ha!), but I hate to use a mobile for telephone calls (except if I need to call when out) — I just use the landline. Occasionally, I send a text, but not very often. My dependence on a mobile phone is for when I do internet banking or make a purchase on eBay (via my computer, up until now) — frequently, they send a security code to my mobile phone by text message, and this allows me to log in securely. Also, it's a standby for my computer giving up the ghost (Like me, it's a old codger, and I should not be able to afford a new Mac computer, which is the only one I would use). It's even useful for in the evenings, when my computer is switched off — I can quickly look something up on the Internet, or even view my photographs conveniently. So, I should not like to be without my smartphone.
What you say about buying a refurb every year seems to make a lot of sense, though, and I shall have a look to see what is available. That would not have occurred to me. It is a way of not being left behind, isn't it? Thanks for your suggestion!
(Added later): Hey, I looked on eBay at Motorola refurbs, and (being an old codger) was completely overwhelmed by the different model numbers. So, if I may be a bit of a nuisance, may I pick your brains? What I should like is a phone with a micro SIM slot AND (what seems to be a) nano SD slot. 4G, with wifi Bluetooth and USB. If you have any way of warning me about the model number showing that it is ancient, that would be very helpful, as I don't know what the model numbers tell a purchaser. Also, any other things to watch out for. Thanks muchly, in hopeful anticipation!
L.L.