APC Smart UPS 1500 VA - one question

I have recently replaced my desi UPS (700 Watts) with an APC Smart UPS 1500 VA (980 watts) which is working perfectly. But there is one question in my mind. Unlike the previous UPS, in the present one the cooling fan does not stop after the battery is fully charged. In the desi unit, the cooling fan and the humming noise used to stop, after the battery was fully charged. But in the APC unit, the cooling fan and the humming noise continues even when the battery is fully charged.

My question is that whether it is a part of built in feature of the APC unit or it reflects some malfunctioning in the new unit?

the fan always runs. your unit seems fine.

Yeh wildlaurel is right. But turns off when the inside temperature goes down. Its functionality is based over inside temperature

well i m using APC from years from rack-mount to desktop . the fan is working all the time to cool down the circuit and proper ventilation .

a simple way to convert any Squar wave APC UPS into Sine wave UPS. i tried it with my APC-500 old UPS it worked great. guys don't waste money in buying expensive sine wave UPS