Steve,
Its good practise to leave the battery conditioner permanently connnected. You can buy a conditioner which is exactly the same as the DMS just rebadged for £ 35 plus Vat from PowerVAMP 01934 643000. they also sell Hawker batteries at keen prices. I have just fitted a PC625 which is used on Jet ski`s and is a very robust battery £56 plus vat.