You don't say what capacity battery that you already have, so it's not possible to give a definitive answer to your question.

On a pedantic note... There is really no such measurement as Amps per hour.

An Amp is an instantaneous value relating to a time of just one second, If a device draws an average current of one Amp for one hour, then it is said to have consumed one Amphour (Ah) of electricity, if it draws an average of five Amps for ten minutes then it has used 0.83 Ah.

So in your case, whilst the fridge may draw an instantaneous 2 Amps when running, its duty cycle needs to be considered.

If the fridge runs at 50% duty cycle, ie 30 minutes out of an hour, then the total draw is 2 x 0.5 = 1 Ah for that hour or 24 Ah for the day.

The fan is likely to be running for the full hour, so its draw would be 2 x 1 = 2 Ah. Incidentally, that's a high draw for a fan.

Your 200 watt solar panels, if used diligently can be expected to produce around 50 AH per day of energy in fair weather.

You may need to do some more calculations of your energy requirements to ascertain whether this is suf 

Are you sure the de-humidifier requires water? I have never seen one where you have to add water, you normally need to remove it from the collection tank as it fills with condensed moisture from the air. You do add water to Evaporative coolers though. 

A 120Ah battery will give you 50 to 60Ah to play with.

200w panels will provide say 40 to 50Ah per day in fair weather, less on overcast days.

Usage will be :- fridge 20 to 40 Ah/day weather dependent, evap cooler, fan and other small items will take about the same depending on run time.

Unfortunately, hot weather, which is when you might expect to use the fans and cooler the most, and when the fridge is the most power hungry, is not the best provider of photovoltaic energy due to the temperature of the panel reducing its efficiency.

The battery may be sited where ever it is most convenient provided cabling is sufficient size to limit voltage drop.

If you intend free camping for only short periods, then the addition of a similarly sized extra battery will double your time without the need for more solar, but you do need to be able to recharge them both in a timely fashion, which may be via the vehicle,  or a charger on mains or generator power.

Some thoughts on evaporative coolers for consideration.

Small evaporative coolers are notoriously inefficient and can result in a significant increase in humidity (up to 90%+) in the van, which, whilst an advantage in dryer climes, can be a problem if the relative humidity is already high, and which also limits the effectiveness of the cooler due to the lower amount of evaporation and therefore latent heat transfer which can take place from the air to the water. The efficiency of an evap cooler is in inverse relation to relative humidity, so as the humidity rises, the efficiency falls, till at 100%, the system no longer works.

Unfortunately in a closed evap cooling system such as is the case with a unit totally enclosed in the area to be cooled, there is no forced ventilation of the humidified air, and so humidity constantly increases.  

An evap. cooler works best when it is sited outside of and blowing into the area to be cooled. 

The moist air that is being produced needs to be able to escape the confines of the van, otherwise the inside of the van will become very wet, this means that you must keep windows open and a free flow of air through the van.

You need to be particularly vigilant with cleanliness of the unit as it is an ideal breeding and dispersal device for Legionella bacteria

 

There are two options for fans as far as RVers are concerned.

Not in any particular order of preference, you can use a normal 240v fan in conjunction with an inverter, or a dedicated 12v fan.

The 240v option has the advantage of a generally larger fan for a lower price, you do need to also purchase an inverter, but this can also be used for other purposes.

If going down the inverter/240v fan path, make sure you get a good pure sine wave inverter as modified or square wave types can cause the fan to be noisy especially on low speed.

If going for the 12v option, consider the Caframo Sirocco or Bora, although maybe a bit more expensive than others, they are a good gimbal type fan. Just Google them and you will get an idea.

I have two Siroccos in my van and find them to be superb.

I got mine from a marine mob in the US who are good to deal with and generally far cheaper even with postage than Australian sellers, I can't remember their name, but if you are interested, I am sure others can help there, or you might see what Whitworths Marine here in Australia can do, they have specials occasionally.

brian wrote:

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What rated power are we talking about here?

A normal car battery is rated in CCA (cold cranking amps), it does not have any Ah rating as such and so would be impossible to determine a rated power for it or to compare it to a deep cycle battery.

Hybrid marine batteries often have both  Ah and CCA ratings (or even just CA or MCA - marine cranking amps - determined at 0°C rather than at -18°C as for CCA), and, where it does have the Ah rating, it will perform similarly to a deep cycle battery of similar technology in terms of depth of discharge, it will be capable of higher discharge currents and faster recharge due to having more plates, but at the cost of a shorter cycle life due to the plates being thinner.

New deep cycle lead acid batteries generally don't perform up to specifications until they have undergone around 10 or so cycles.

Also be aware that the term AGM is a method of construction, it does not confer proof that the battery is either a cranking or a deep cycle type. 

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HI

DITTO to ALL above

It also surprises me that, despite many posts over a looong time,many STILL do not appear to KNOW/ understand that AGM does not automaticaly mean  "DEEP CYCLE"!!

-- Edited by oldtrack123 on Tuesday 5th of November 2013 01:27:47 PM

I bought as small 240v fan from Bunnings I think they are about $10 but use little power 15w.

Ensure you buy a good battery such as an AGM as a normal car battery will only give about 20% of rated power when new where an AGM gives 50% when new.

Regards
Brian