I connected 8, 100Ah battery with APC 2.2KVA inverter, now it doesnt give correct battery indication and keep producing beeping noise, whats the problem?

The reason is 100AH is not advisable to connect it on APC2.2kva because of battery charging issue.

Continuous Beeping (theamber On Battery LED will be illuminated)
This alarm indicates that the UPS has reached aLow Battery condition and will soon shutdown. The UPS can only operate onbattery for a limited amount of time. In order to protect the unit's batteriesfrom discharging too much, the UPS will shutdown and turn off its output. Towarn you that the unit will soon shutdown, the UPS will sound this alarm 2minutes before actual shutdown. With optional Powerchute Plus software, 2minutes can be changed to 5, 7, or 10 minutes to give you more of a warning ofimpending shutdown. If you hear this tone, you should immediately gracefullyshutdown your operating system to prevent data loss or corruption.
Note:This graceful shutdown will occur automatically if Powerchute PLUS software isbeing used.

Constant, Solid Tone (the red Overload LEDwill be illuminated)
This alarm indicates that the UPS has detectedan Overload condition. If this alarm is sounded, try removing non-essentialequipment. The alarm will remain until the load is reduced. To determine ifyour UPS is capable of handling the equipment you want to protect, visit APC'sSizing Guide at www.apcc.com/sizing.

Continuous Beeps for One Minute; RepeatedEvery 5 Hours (Replace Battery LED will be illuminated)
This alarm indicates that the UPS has failed itsSelf-Test of the battery. The unit will continue to sound this alarm until theunit passes the test. Try to let the unit charge for a few hours and thenperform another Self-Test (Press and hold the on/off button until the second'chirp', then release). If it fails and the unit is still in-warranty (twoyears from date of purchase), then contact APC. If the unit fails and its outof warranty, then order a replacement battey cartridge through your reseller,distributor, or from APC's web site.