Do not try this at home, but I replaced the lead acid battery in my UPS with a LFP battery. From what I read online, the charging curves for lead acid batteries and LFP batteries are very similar. The LFP batteries have a slightly higher charging voltage, so I expect my LFP battery to only charge upto about 80% capacity or so due to the charging voltage being slightly too low. I'm hoping the battery will last 10 years instead of 2 or 3 years.

Do not try this at home, as changing battery chemistry is quite ill advised.