Here is a very effective method to double the service life of a LifePO4 starter battery. I used these on my car and they have beyond impressed me. They cost higher than lead acid but their advantages make me want them around for a long time.
Step 1: Interleaved Service.
This method requires a minimum of 2 batteries. One I labelled as the "A" battery and the other as the "B" battery. IF for example each battery can give me 5000 starts, then if i started my car 3 times every single day, I should get 4.5 years service out of a single battery provided I use only that battery.
To double this figure, I use one battery in the car and the other in storage within my refrigerator (Don't worry, LifePO4 is NOT toxic and those temperatures are ideal for its long term storage). Every 3 months I rotate the service of the battery, that is I swap out the A for the B and vice versa on the next 3 month rotation.
Doing this will give me the same number of starts in each battery (the battery can only provide a fixed number of starts to the engine before its chemical reactions die out), however I have effectively doubled the calendar service life per battery, in my example 9 years!
Yes I know that its double the cost but the long service life per battery plus its other advantages has made me fall in love (yes LOVE!) with this battery chemistry.
For my current car or a future fuel injected vehicle, these two batteries should give me long life! Imagine a battery spanning multiple vehicles. So groovy!
Its important with LifePO4 to balance the internal cells from time to time for maximum service life. I do this on both batteries each time I make a 3 month rotation swap. I use my multi-chemistry charger and the built in balance port on the Shorai LifePO4 batteries to make this happen.
If in the not to distant future when fully Electric Vehicles become viable with standardized battery packs, for sure I will employ this method to make sure I have long life power sources. Of course I'm gonna need a huge refrigerator to store those large batteries. Ah, future dreams!