after 1 year, if my iphone6s battery can only last 13hr (normal usage), instead of 1 day is it normal or its time to consider changing battery?

planning to get iphone that will be released next year though so battery change is it worth it?

13hr standby,usage 1-2hr

Ok thanks for the suggestion
Yeah warranty ended in September

Thanks I do experience unexpected shutdown but rarely so I think I will go and try my luck

Thanks

Mine is Q8.btw which service centre is recommended QCD Berjaya Times Square or Machines in Northpoint

I enquire with Machines and as per below are their reply
The program affects devices within a limited serial number range that were manufactured between September and October 2015. Perhaps you can share your serial number for us to advice you further.

After I reply with my serial number with Q8 in it, they reply:
Your device is eligible for the battery replacement program. Please note the following before visit Machines Service Centre.

1) Make sure all data is backed-up (the Service Center do not provide data back-up service, all data will be erased once the unit is surrendered)
2) Disable Find My iPhone (FMiP) feature from the unit.
3) The program will replace only the battery.
4) Estimation whole process is 7-10 working days (excluding weekends and public holiday).
6) No loaner/temporary unit will be provided.
7) Accessories such as screen protector/tampered glass is not covered and consider loss once the unit is surrendered.

when I enquire if this can be done in a day, this is their reply:
The process is done by Apple. The process take logistics, parts import and availability into consideration.
Feel free to contact Machines Service Centre for further advice regarding this.