All 6 rakes of KK exp and SBC-MAS-SBC Mail comprise of coaches manufactured in the last 3-4 years and 98% of reserved coaches (SL,3AC,2AC,1AC) have charging points in each bay as a result. Even the older ones are POHed ones and they too have charging points in each bay. Only around 2 or 3 coaches among the 114 (19*6 rakes) do not have charging points so go ahead and test your luck :)
P.S: SWR does shuffle coaches here and there sometimes and the replacement ones too are newer ones having charging points in each bay.