Yes that lead appears to be trying to get blood put of a stone. USB sockets give nominally 5 volts in the 1 to 3 amp range. Give the loss in the voltage convertor you would be very lucky to get even the 8 watts mentioned.
If you don't have a cigar lighter socket and need a 12 volt up to 15 amp supply fit a Hella style socket and wire it in to a 15 -20 amp fused battery supply. Cigar lighter sockets are rubbish.
Agreed. I had already thought that this is the only sensible option. I already have the necessary hardware and will make up a small fused harness which I will permanently connect to the battery.
Which I have now manufactured and fitted with interchangeable plugs so exchange between trickle charger and power for compressor is a few seconds work.
So, now all I have to do is find somewhere to stash the compressor, the jack, the can of goo, the spanner etc. Pity there is no quick and easy access to the cover over the spare wheel well. Plenty of space there!
