The solenoid, when it's pulling in, can easily pull 30 - 35A, so a bigger fuse necessary I'd say. Or live life on the edge and do away with it completely.
kits appear to come with 30A fuse, for example https://www.offgridcamper.co.uk/product/hot-start-relay-kit/ Might plonk with 30A and see how it goes.
That kit looks a bit odd. You'll need a hydraulic crimper to put that terminal on, and I'm not quite sure why you need 5m of thick cable. I don't think they really understand the problem. Just buy a boggo 30/40A relay (you can get them with a built-in fuseholder from Halfords) and make up the wiring yourself. Not that difficult.
I bought a kit , empi, some years back and the wires colours didnt match the instructions. The colour of the wires were not the same as one printed . Somehow i worked it out but i cant remember the exact issue EDIT just realise ive already posted this.
Yeah that’s the plan to make it up myself. This was just an example I found online. I’ve got everything I need, just wanted to check on the relay.
