I don’t have anything to add in terms of solutions, but I think it’s worth trying to understand why your batteries only last 1 or 2 years.
If it’s because they’re too low capacity for your needs and you’re deep draining discharging them often, then you might be able to save money in the long term by getting a larger, more expensive UPS. If the environment where they operate is harsh (eg: too hot), maybe the fix is actually air con or something like that. And so on.
Batteries can last a long time, but you need to avoid the extremes: temperatures, state of charge, charging cycles, etc.
No. For most (if not all) batteries the recommendation is to avoid discharging them too much.
Having a larger battery helps here because you won’t go as deep. On a larger UPS, maybe you’ll be at 30% when the power returns instead of being at 5%. On a phone, it may reduce the number of charging cycles because you no longer need to charge during the day or have to go too deep. On EVs, a larger battery means that you won’t have to fast charge as much during trips and that you won’t have to charge it to 90% to reach the next charger or arrive with a very low state of charge.
Larger batteries also allow devices to age better. If I get a phone that barely lasts me a day, I’ll probably have to replace the battery or carry a power bank around after a while. On the other hand, if I always end the day with 20-30% left, I’ll only have problems after losing ~20% of capacity. It’s the same with a UPS. If we find ourselves going down to 5% when it’s new, then 2 or 3 years later that USP won’t be enough for our load/outages and will shutdown before power returns.