What's the consensus here on the Lithium Iron Phosphate vs AGM Lead battery debate? I'm looking at building a 5Kw battery bank for a solar inverter. On paper, the lithium batteries are superior, smaller, lighter, and greater longevity with greater depth of discharge. I'm also aware of how they become useless if the BMS goes and tend to blow up in EVs. If one of those things goes my house is toast. Lead batteries seem more constrained but have more peace of mind. I don't know how reliable Lithium Iron Phosphate would be in a TEOTWAWKI scenario.
I think if you compare LiFe with LA with equivalent Amphrs (even at 50% discharge for LA), you find the LiFe bank to be much more expensive. The LA bank will have a long life so long as you stay above 50% discharge and you take care of the bank properly.
My rudimentary understanding of lithium iron phosphate batteries (LiFePO) compared to older and more traditional chemistries is that they have a number of advantages compared to the older batteries/chemistries. A key and one of the main advantages seems to be that they have much higher cycle lives. Which basically means that you can use them for a longer time before they deteriorate and start to deliver less energy. That is,
if you take care of them and/or use them correctly.
My understanding is that if you for example store pretty much any battery type without use, there are certain time spans where the battery will suffer considerable damage/loss that can go as far as destroying it (usually as low as 3 months without use. And most often 6 months without use). That means if you let such batteries sit in storage for longer than that (let's say 7 months or a year or more) you have to expect considerable loss/damage to the battery/chemistry and even to the point of destroying the battery!
Besides those considerations, we don't really know how LiFePO batteries will cope in the long run since it is a rather new technology that hasn't been used for so long. For traditional lead acid batteries, on the other hand, we know more or less how they cope in the long run since they have been in use for decades.
I personally have opted for LiFePO in some of my batteries, although I think it is perfectly reasonable to be on the "safe side" and use old school lead instead if you are worried how it will work in decades ahead.
By the way, there is a new kid on the block, that will apparently soon get
mass-produced and might replace Lithium-ion altogether while being better than LiFePO in a number of ways:
The sodium Ion battery.
One of the big advantages of that new battery/chemistry will be its ability to be used and useful in considerable
minus temperatures, which is something other current batteries/chemistries have real big problems with.