OEM battery lasted 3 years and 2 months on my Punto diesel. I changed it again to a 50Ah exide ( 18 months warranty) that's been in use for around 2 years and 3 months. It's now showing signs of weakening with Airbag failure messages and slow cranking. I don't have any extra electricals , sometimes use the battery port to charge my mobile. Any recommendations on a long lasting battery ? Are Exide batteries designed to conk off after the warranty expires ?