The discharge rate of 48V lithium-ion batteries is often expressed in C ratings. For example, a 1C rating means that the battery can be discharged at a current equal to its capacity.
DC 48V is the telecom industry's best compromise between history, efficiency, safety, and ecosystem maturity. Historically, rooted in lead-acid batteries and reinforced by decades of practice.
Technically, most 12V inverters cannot be directly converted to 48V. Here's why: Internal components (transformers, capacitors) are rated for 12V input. Safety certifications become void after modification.