Compared to VRLA batteries, Li-Ion batteries are much smaller and lighter. Li-ion  batteries, on average, weigh 60-75% less and take up only 40-50% of the size  

(footprint) of equivalent VRLA batteries. Another way to look at this is for the same  amount of battery capacity (Wh), Li-Ion batteries take up roughly half the space  of their VRLA equivalent. 

Taking ventilation requirements and/or the need for VRLA batteries to be located in  a separate room into account, the footprint required for Li-Ion batteries and thecost associated with that space, reduce even further.  

Less size and weight can also contribute to savings in shipping, handling, and deployment costs. When a Li-Ion UPS is used in an In-Rack or In-Cabinetpower architecture, it may consume 2U to 3U of rack space, while a VRLA UPS of the same capacity would consume 5U to 8U of rack space. Using the Li-ion UPS would allow the user to “reclaim” 3U to 5U of space, which can be dedicated to  revenue-producing IT equipment.  

THE EFFECTS OF CHARGING AND  DISCHARGING ON BATTERIES 

Charging, discharging, and the effect it has can vary  greatly when comparing Li-Ion batteries to VRLA batteries. VRLA batteries start losing capacity from  the very first charge/recharge cycle and continue to  lose capacity with every charge and discharge cycle  thereafter. VRLA batteries reach their “end of useful life,”which in a UPS is generally defined as when the batteries hit 80% of their rated capacity in  ampere-hours, much more quickly than Li-Ion  batteries. Li-Ion batteries have a higher cycle life for a given depth of discharge, and depending on the chemistry, they can withstand more than 2000 charge  and discharge cycles with minimal impact on capacity.