Hi Derek
Good question ?? IMHO the problem with the small rechargable batteries is the usual problem of being designed to fail after some time to keep sales going. No profit in things that last for years. But do not go back to Nicads as they had their problems too. They need careful attention to keep going. We had some CDMA Nokia phones from ?? that had a torch in the end and we kept them till only some years ago and the batteries were still good and only needed a charge a couple of times a year.

I have two 40Ahr lithium batteries that are about 8-9 years old and only get charged occasionally when I need to use them and they are OK and seem to have full capacity. They have not been worked hard though. I think the newer style of drop in units may be a different story but it will be revealed in the future how they go !
Jaahn

I haven't used LFP batteries yet but have been using Li ion and NMHI for years and found out in the early stages it's all about the charging, I will use one brand as a guide, brand X, I bought about 20 for different uses throughout the home, they came with a charger that you simply plug in the wall and overnight they charge upto 4 AA's, AAA's or a 9V, the issue is they charge on a timer not on voltage, therefore they were being over charged in most cases and I was only getting a few years use out of them, not long after buying these I also bought a industrial 18v screwgun, drill set which also came with a charger, this charger is multi stage and tells you when the battery is full, overhot, dead and shuts down when the battery is full.

Now 15+ years later out of those 20 original AA's and AAA's I think I have maybe 10 left some nearly dead and some (most likely newer ones) still going strong, the screwgun and drill batteries (3) a bit tired but still do as intended, a few years ago I bought a 17.5Ah purpose built Kayak battery the charger that came with it was IMHO something similar to the ones you get for phones and alike, so I bought the upgrade model charger (a hobby charger) this charger is a proper balancing charger $49, you set the type of battery (chemical) and its build (number in series) and capacity (not needed) then press start and it then asks for confirmation, it checks the battery then starts the charge it records the input to the battery and shuts down once charged, the charger has a 6Ah output and you can watch the display and see what it's doing while charging, my kayak and screwgun batteries are made with Li ion 18650 and have never given me any issues charging this way, my other batteries are charged with a similar self contained charger purpose built for Lithium/nicad that you can buy from Jaycar or any e cigarette shop.

Just like you buy a specific dc to dc charger for your house batteries the same consideration needs to be given to your rechargeable batteries I'm yet to find a way to charge my phone or other self contained battery products, although a thought  just occurred to me that I connect a cig lighter adapter/usb to my chargers output and run things from that and hope it doesn't conflict.

Im a tradie and I find that 18v lithium batteries are pretty well shot after 2-3 years.
Im having a dual battery system installed in my new HiAce van next week, my auto elec said to stick to AGM.
In his opinion I can buy/replace a few AGMs under warranty for much less than a lithium battery cost, he also says that the warranty period on lithiums are reducing I dont know, but thats what he tells me, he works this stuff daily I dont.

As PeterD stated you must be careful comparing the various types of Lithium batteries.

This link provides information about the various types, their typical applications and life etc.

 https://batteryuniversity.com/article/bu-205-types-of-lithium-ion

Ken

-- Edited by kgarnett on Wednesday 25th of August 2021 12:39:07 PM