Acer Aspire ES1-311-c4q6 with critical low battery message

hi

my friend laptop which is a Acer Aspire ES1-311-c4q6 comes up with the messsage critical low battery message.

the current battery is AC14B18J (31CP5/57/80)

Does that mean it needs a new battery?

what causing this problem?

is there a way to run it without a batterry?(i tried removing the battery nothing with connected to PSU)

just want to confirm putting a new battery in will fix it , it a lot too spend £45+shipping from batteries-mail.co.uk ?

http://www.batteries-mall.co.uk/replacement-for-acer-ac14b18k-ac14b18j-laptop-battery-48wh3220mah-p-5795.html

it out of warranty friend brought it recon about a year ago off ebay had no other problems with it.

mark