So...
One year on and I have at last managed to get around to fitting a 12v accessory socket so I can charge my 'phone, etc. It's a marine-grade socket which I've attached to a fly-lead which terminates in a plug to match the lead/plug which attaches through the bulkhead and directly to the battery terminals. This has an in-line fuse on the +ve side.
The latter has been on the car for some time, used as the plug-in point for my garage battery conditioner, and has worked faultlessly for years. However, the 'phone/USB plug worked only until it blew the in-line fuse which upon inspection appears to be a 3 amp (violet in colour) blade. Is this a simple case of upgrading the in-line fuse to, for example, a 10 amp? All of the cabling is uniform, including the new fly-lead I've attached to the accessory socket.
If so, will there be any potentially adverse effect to the conditioner if I upgrade the fuse? Sorry to say I really wasn't paying sufficient attention in Physics all those years ago when we studied electricity...
TIA,
Pierson