battery for acer aspire 5536

Hi .My 2 yrs old Acer Aspire 5536 needs a battery replacement as its current battery is not providing backup of 1 min only. I asked auth service center and they said battery will cost 3500/-

Hows this battery? Its only 1600/-

Acer 11.1v 4400mAh Aspire Laptop Battery 5517 5532 5536 5536G 5541 5541G 5542 | eBay

Please advice

Rgds
Sumit