Old age and moisture from years of use and washing. Must be at least 13/14 years old now possibly more. Time for a checkover and refurb of the electrics by the look of things.
Got them today mate, thanks. Problem is I think I need to make some type of connector for all those live cables to a new battery terminal! Any ideas?
Yeah the lead has broken down for sure, causing loads of resistance in the wire which is why it’s smoking, don’t mess around, just replace it, it’s carrying a lot of load
Think you need an electrician - I guess your not working within the standard battery box with it's constraints? If so it will be difficult to fit a connector box further back. Get professional help (for the wiring I mean)
@Sev recently added a link to a busbar option, or you could look for a soldered eyelet (or two) if you're happy to do it. just an example:- https://www.ebay.co.uk/itm/Crimp-So...hash=item3b335c2f5f:m:mcBxKDeEKX6TlsqXgzSoUeg you need the large capacity type but with the "smaller than usual" fixing hole.
Heat due to resistance, Resistance due to poor connection Poor connection due to corrosion. I know an old lady who swallowed a fly.