Thanks for the clarification. It's just that I've been offered 2 x 15s at a very cheap price and wondered if it was worth me having a play and learning a lot more. I could make up 1 x 16s and 3 x 4s but as I have found out they are only 50ah cells, the 16s would not really be practicable on its own for my home use, hence my thoughts on making the 4s batteries for 'RV' use or even fishing/picnics etc.
I suppose hobbies cost money and learning a lot more about something 'cheaply', is better than throwing a lot of money at it
@SeaGal - you blasphemer, you!! Lol - @£300 for two pre used 15s batteries to play around with?? Should I deal or no deal??