i changed 3 times my car battery but problem did not resolved,i take the car to service center and they say-ed may be from ECU or BSI.they guess my car drain battery when not working.i use my car every day

the problem may not be ur battery,it could be the fact that the alternator is not charging it fully & the electrics in the vehicle r running on mainly battery power.You need a charging check.The alternator should be pushing out between 13.8 and14.4v between 45 & 80 amps full load depending on engine type & size.If this is ok a battery leakage test needs to be done to see is there is any current flowing with every thing turned off,shouldnt be any more than 0.5amps.If its more than this open the fuse box & start pulling the fuses one at a time until it drops below 0.5 amps,when u pull the fuse that does this then thats the circuit thats draining the battery & needs further investigation.