My Sargent PSU2007 unit has a noisey fan on the charger unit. I was going to remove it and lubricate/replace it. I've been reading posts about intelligent multistage chargers and also how the PSU2007 unit has just a fixed voltage charger. If I leave the PSU2007 alone and don't switch the charger on can I add an intelligent charger in it's place and connect up to the leisure battery. It seems that an intelligent charger would be better for the battery (which needs replacing!). Or am I missing something?