Lithium Batteries / charger for Boat

[wiperhunter2]

Jeff said,"Lithiums should be stored at 50% charge, that is like 13.15 Volts.."How can 50 % of the charge be 13.15 v are you talking about 50% of the charge for 24 v system?  If you are talking about 50% of a 12 v battery, shouldn't that be 6 v?