Hi every one ... I have a UPS with 12V 7A battery .. i want to replace the battey with 12V 100AH battery with an external charger. The problem is i don't know how to cut out the built-in UPS charger?

You do not need a battery, you need many.
You need knowledge to replace these batteries in a safe manner.
Then you do not know where to buy batteries should ask a company for help ...

you should check the inverter and the charger boards as well.
Mainly IGBTs and drivers (IGBT drivers).
better locate the fault and replace the defective board

Hi Mike,

Electronic circuit issue,

you have to repair unit or replace the circuit bord.

regards,
nuwan.

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.

disconnect one terminal of the battery then measure charging voltage betwen +ve and -ve it should be 13.8vdc for one 12v battery if charging voltage is not present then battery is ok then connect ammeter to measure the current in Ampere .take care it should be in series if current if no current then battery must ok opern the ups there is a charger transformer measure i/p voltage to transformer if not present then check i/p path if present then check diodes at o/p of charger if faulty replace it also check capacitor and regulator ic if faulty replace it your problem must be solved

Yes.

disconnect battery terminal and check charging voltage it should be 13.8volt per 12v if not present then check transformer, diodes, ic 317if faulty replace it

Yes you can change the battery. All you need to do is ensure that the replacement battery has the right physical size to fit in the cabinet and meets the required spec. Simply having a larger AH rating means that it will last longer under load when it is required and will take longer to charge after it has been used.

The time will lower the longer u keep using it. Every (Chemical) battery needs to be replaced periodically and maybe its time to change your UPS batteries too. Since you were using double battery, it is supposed to be replaced every 4 yrs or so if it is used regularly.....sodeep

It need to replace 2 piece of regular 12V.7A SLA battery. It is easy to buy in the market.