Keeping the leisure battery topped up

Whatever the technology 6 Watts is only ever 6 Watts, and come the low sun angles together with the shadow issues that come with that, the shorter duration and the typically greater number of overcast days, IMO 6 Watts will never cope with winter.  Have you measured its parasitic load at night? I have come across panels that actually drain more in the winter than they yield.

£100 for 6 Watts is eye-wateringly dear £s per Watt, there are far more cost effective solutions even reaching your reasonable 40 Watts target for little if any more.

Far better to get a decent solar setup installed permanently on the roof. Go for something in excess of 100W and it will give you greater independence from EHU.

Indeed, I think the winter will be a test to see if there is sufficient light just to keep the battery topped up in storage. I am aware that some panels do drain the battery at night. I believe the diode and associated circuit prevents drain.

The permanent solar panel would be useful if we ever wanted to go off grid, but we are never far from and EHU. Unfortunately, I don't have the spare payload to mount a permanent fixture. One of the advantages of a MH?

The Milenco 6w pulse charger seems to be made by Optimate. They seem to market several different ratings under their own name, right up to 80w. One of the larger sizes might be a better investment. LINK.

I’m afraid I agree with ocsid on this £100 is eye watering as is the smoke being blown into my eyes over undefined “different technology”. Far better to get a decent panel put onto your roof.    If you opted for a semi flexible one.  These are so light you could leave your cable at home and result in a weight saving. 

Edit.  The claims on the box are also in my opinion misleading.  To claim that the 20 panel can output 1 .7 amps would mean that voltage is less than 12v ( W / A= V) not much charging going on at that voltage. 

If you don't need constant power for an alarm or tracker, take it home and keep it topped up there. Six watt in the winter is neither use nor ornament.