Battery trickle chargers - advice please.

I have a single smart charger on the leisure battery and simply have a pair of shrouded connectors on short wires that let me connect the two batteries together across the charge splitter unit .
I make the connection when leaving the mains connected into the bus with the cover on.
As both batteries are wet lead acid this works.

 

The Aldi one is unbeatable for the price. Will do 6 or 12v batteries and has a digital read out showing the state of the battery and with a 3 year warranty.