battery drain watch S4

i bought a apple watch series 4 10 days ago and i charge it up to 100% take it off charge and when i wake up at 7am my battery has already drained to 60-70%. I have just enough charge to last me about 9 hours. i tried to get a refund from Argos but need proof from apple. my friend has a S1 and uses it for 2 days.