Bongo Fury

Hi guys my van is fitted with a volta 18amp intelligent charger which has to settings one called 3 stage and the other called float does anyone know the best mode to choose

The three stages are for charging a battery which is well discharged or in an unknown state, the float charge is just a very small current designed to keep a mainly unused battery at the fullest charge, normally the third stage is virtually identical to a float charge. See this link to the Battery University.