Here are some pics of the original battery which came with the laptop.
The primary use for the battery will be for use when there is no power plug easily available, e.g. in the car, at a crowded coffee shop etc.
So, about 80% of the use will be with the power outlet.
There is one option on Amazon Puredick® New Replacement Laptop Battery for Dell Inspiron 15-5547 Series, TRHFF, 1V2F6, 01V2F Laptop Battery -12 Months Warranty[Li-ion 3-cell 11.1V 43Wh for $29.99, does that seem ok?
Does anyone on here know if there are any third party retailers/websites which offer comparable batteries at a more competitive price?