The sequel to the current Apple Watch is rumoured to be launched in mid-to-late 2016. A research memo by financial services firm Cowen and Company suggests the second generation Apple Watch or, Apple Watch 2, will come in an even thinner size and receive some performance boost.

The Cowen memo has been obtained by Apple Insider. Apple's original smartwatch was unveiled on 9 September, 2014, but went on pre-order only on 10 April, 2015, followed by shipment on the 24th of the same month.

Apple usually sacrifices battery life in favour of a thinner design, but on the contrary, to meet the demand in the wearable segment, it might also consider bringing out a wearable device that lasts for 24 hours or, more on a single charge, according to the memo. Speaking at the WSJD Live Global Technology Conference recently, Apple CEO Tim Cook admitted that users would need to charge their Apple Watch every day.

The Vector Luna smartwatch starting at £219 delivers an impressive 30 days of battery life, beating all other rivals in the smartwatch market that is dominated by tech majors including Google, Apple and Pebble. Meanwhile, Swatch has confirmed it is working on a smartwatch whose battery will last for six months.

Apple is likely to ship 18 million smartwatch units by the end of 2015, and about 45 million in 2016, anticipates Timothy Arcuri, managing director at Cowen. The firm separately estimated 40 million iPhone shipments for September 2015, with the fourth quarter shipment to hit 70 million units.