Until recently, as long as the battery back up did not bother me I left well alone... Now the bbus ( on my Defender) is disturbing my alarm system, so I either need to disconnect permanently, or replace. But the part is completely out of stock... Any bright ideas? Not sure if the p38 one is exactly the same, but probably the p38 one needs replacing too

Is there any chance of opening it up and replacing the well tired NiCd battery with a NiMH one? Mine doesn't have one, the Ascot and the red 4.0SE both had one but its been unplugged.

I tried that, but they drenched the circuit board in silicone rubber, and by the time you have excavated the whole thing there is no trace whatsover of the pcb, just green lacquer stuck to rubber:-). It wd have been so easy to just have a separate rechargeable battery...