A321 Ramp Agent reported being heavily overworked in exhausting work conditions due to staffing issues. Battery-powered wheelchairs being loaded into cargo without proper tagging and information also caused delays and safety issues due to the potential risk of fire from the lithium batteries in the cargo hold.

Narrative

Working turn on Aircraft X. As soon as Load Planner released trip; gate crew began to load aircraft for outbound trip; 1 hour before departure. Expecting 200 bags with gate checks and at that time no support given to accomplish task; thus earliest start with load plan. After forward belly loaded with 99 bags; gate crew was sent to assist on outbound after their lunch period. At that time half the trip was loaded and no assist was needed - plenty of time on clock. Gate crew continued to load aft belly. No sense having 8 clerks jam bags into one belly. Near end of loading aft I noticed Company bringing non-power wheelchairs to base of jet bridge and was told to expect at least ten wheelchairs; aft load was adjusted by me to accommodate. Was made aware shortly after by Ramp Manager; they received word to expect 2 power wheelchairs; 400 and 200 pounds each and they recalled gate crew to help again. Made room in forward cargo to accommodate. After receiving 13 wheelchairs for aft cargo late and 3 power wheelchairs after departure time for forward cargo; totaling 1140 pounds for three pieces. Flight left taking about 1 hour delay; while working gate crew for 2 hours in [summer] heat; nonstop.Always happens here in ZZZ and no managers are fixing issue after it is known to them. I fear for flight safety because of management/headquarters lack of concern; spoke cities feeding ZZZ also send power wheelchairs to us the same way. Also lack of man power here in ZZZ is pushing ground crew to extremes. Big safety concern when we cant focus on job at hand.Event is power wheelchairs not being marked proper or at all battery type on tag. Causing big delays and safety issue of flight if wheelchairs with lithium batteries energize in flight causing fire in cargo hold. Customers do no know battery type; passenger service does not know because lack of checking; and Company have no clue on airline procedures. This leaves me to look out for flight safety. A few weeks ago; against my recommendations; passenger service / Passenger Manager on Duty and flight deck crew pilot; lead acid batteries [were] taken to cabin for flight - of course no battery boxes available for loading in cargo hold. Too many times this has happened on my tour. Also no one; I have to say 'no one;' disconnects power supply as per regulations. Not to mention today event telling me 'no batteries' in device; so I showed Ramp Manager how the power was mysteriously still powering wheelchair. The event is also; not only the company allowed gate crew to work constant; but added another quick turn trip to gate with no support and very little cool off period. And push for crew to resume without adequate cooldown after 2-hour task.Power supply traced and discounted on two of the wheelchairs. Third had to be dismantled removing positive and negative lead to batteries. Ramp Manager got Phillips screwdriver from Facilities Maintenance. Lengthy delay happened.Event with power wheelchairs is being overly complicated by training in headquarters by too much info. Wet batteries go in boxes down below; if it's dry; gel or sealed; stays in equipment - preferably upright - also power supply 'disconnected' and taped. Pretty easy. Being adequately staffed for gate support also an issue. After this turn; another on the ground flight with no support pushing me and my crew to physical and mental exhaustion. Me not even realizing that we where working international flight till almost departure because of constant push and prodding to get back out there and not having any support nor cooldown period 10 minutes only. Tail to tail bags did not connect. Can not focus on task if workload is pushed at this pace. Not to mention opening company up to injury or worse of employees.