I have had the Inspiron 13 7380 for about 24 months, the battery has rapidly deteriorated in that time that now it lasts about 30 mins from start up, after what I thought was a full charge. I have changed all my power settings as per = Dell Laptop Battery - Frequently Asked Questions

but it still rapidly discharges. I see that the batteries are not readily accessible on these laptops? What options do we have to have these investigated or changed?