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I've written some advice here on batteries and solar panels...

http://www.glenp.org.uk/batteriesfaq.htm

This is taken from experience and research, but usual disclaimers apply!

I have to say that I would expect an 85Ah battery to last around a week if you're not silly with the usage.

Glen

I use a 13w briefcase solar panel which is more than enough to top my battery up.
I only had to use a battery charger once during last season.
I have a small caravan and run 2 LED strip lights and mobile phone/DS chargers through an invertor.

Have you rallied for 7 days/nights before? A couple of nights without EHU is easily covered, but 7 nights bearing in mind that you may have children? can be quite a challenge; especially when you factor in our famous weather!

It really depends on how you and your family/travelling party relax chez caravan. Each of the contributors here will offer slightly diferent advice because we all want/need/aspire to slightly different entertainment during the course of a day/week.

If you are happy with no or at least very little tv during your rallies, irrespective of weather or 'must see programs' (Olympics perhaps if you are sports minded) then you may be able to 'get-away' with a lower wattage solar panel. (For tv, substitute  radio, laptop, games console, slow cooker etc although the latter would need an inverter).

The use of these items heavily draw on the battery and over a sustained period of time, a lower wattage panel wouyld not be up to the task.

Glen P's article and link is an excellent review based on experience: not what the salesperson wants you to hear!

From looking at solar panels at the Excel camping and caravanning show, a very rough guide to the maximum output of a panel equates to each 10w panel size will return approximately .6 amp/hr charging capability. Therefore, a 60w panel, under ideal circumstances will return approximately 3.6 amp/hr charge. Factor in cloud, shadow, less than ideal conditions, sun rising/setting etc etc and your average hourly charging rate may be considerably less. You may get somewhere near the advertised rate perhaps two hours before and after the sun is at its zenith, but each hour before and after this critical point will show a commensurate reduction in the panels capabilities. I refer you to Glens article again.

Personally, I would rather pay slightly more for a seemingly oversized panel (in terms of wattage rather than sheer physical dimensions) to allow for all of the potential limitations listed above. After all, if the panel is only producing 20% of its capacity, then 20% of 7.2 amps or above is far better than 20% of 3.6 amps. The difference may make the difference between 'surviving' a week away and enjoying a relaxing break!

Hi, We run 2 x 80W panels into a 110Ah battery and never had any issues at all and we do run quiet a bit of kit off it. However, I have just got my hands on one of these http://www.maplin.co.uk/12v-50w-telescopic-vertical-axis-wind-turbine-396269 which if it works as I hope will mean I will be able to keep charging even when its dark, wind permitting that is.

Hmmm, See your point Nigel 16, hadnt looked at the reviews until you said about them. I was given the unit by a friend who had planned to use it on his motorhome but he ended up selling the motorhome before he fitted the unit.

Oh well, im going to give it a go anyway and see how I get on.

Dave