mummeee74 wrote:Komodo I have been looking into your suggestions, I think the 100AH battery is what we need, but WOW didn't expect them to be soooo heavy. If we had one of those and the solar panels to charge do we also need an inverter or a Waeco battery pack thingy? I am just not sure how it all connects together? And if you go out for the day to the beach do you pack up your solar panels or do you just risk them being gone when you return?? (mmm or perhaps I need to review my camping locations!)
100aH battery has a LOT of lead in it and lead is heavy. I would expect a 100aH battery to be pushing close to 30kg+
You only need an inverter IF you want to power 240V accessories. BUT note that 240V accessories will drain you battery fast.
(getting a little technical - skip this if your not interested)
The maths is :
I = current (amps)
V = Volts
P = power (watts)
I * V = P
P / V = I
So lets say we have a fridge that uses 60watts running off a battery :
60 (watts) / 12(volts - battery power) = 5 amps (how many "ampere hours" or AH it will use per hour)
how ever if that was on mains power the equasion would be more like
60 (watts) / 240 (volts - mains) = 0.25amps (how many "ampere hours" or AH it will use per hour)
As you can see what ever current an appliance draws @ 240V (mains) it will draw 20 times the current running off 12V (battery power)
If you using an inverter to setup from 12V to 240V then there will be additional losses as no inverter is 100% effecient. Even some of the best square wave inverters are only about 85% efficient and most true sine wave (the best type) inverters are only about 60% efficient.
So 240V accessories off an inverter are typically REALLY inefficient. Avoid where possible.
Where the maths becomes more tricky is that the 60watt 12V fridge above might use 60watts or 5amps per hour if it runs flat out 24/7 but the fact is most fridges only run about 30-40% duty cycle so 5amps x 0.4 (40% cycle) = 2amp AVERAGE draw per hour. (read this!)
My suggestion in all honesty if looking to go a 12V compressor fridge is definately think about how you are going to use it. A smaller fridge will use less energy. The higher you set the temp the less energy (power) you will use. Most food that needs to go in a fridge is fine at about 4degress C. So a small (~40L) fridge which just has perishables stored in it and only opened 2-3 times daily plus an esky filled with ice (or dry ice) for storing drinks is often a better way.
As for solar and how best to use it - really it needs to be in the sun 100% of the time. Now if your going off doing trips away from site during the day perhaps you need to concider how you set them up. Is it possible to have the permanently fixed to the camper or fitted securely to the roof racks of the car rather than completely portable and thus easily pinched?
Remember they arent small either the average 80watt panel would be (from memory) about 900mm x 475mm and they dont just roll up ready to stuff in the car either. They are a large bulky item.
IMO an esky with ice / dry ice is a better option for most travellers in your situation. A fridge is a bit outlay and when you factor in batteries, insulation bags, fridge slides, solar &/or generator charging systems you could be up for close on $3k for a 40L fridge.
I have an 80L fridge freezer and these days because I have a dog to concider now (lab x retriver) he takes up the space I used to store the fridge & batteries so most trips I end up taking an esky and doing a run to town every day and a half - 2 days and grabbing a bag or two of ice - which on most trips means just one trip into town over the weekend.
I only take the fridge these days on bigger trips where I either have the trailer or I'm not taking the dog. That said the trailer seems to be coming on more and more trips away with us - but I have a big 4x4 to tow a little 6x4 trailer. Where as you have a small vehicle and your already towing a camper.
Remember 1000's of people go away for weekends buy with no power and no fridge. Perhaps a few short trips without a fridge is in order before you take the plunge into buying a fridge.
Don't get me wrong I think compressor fridges are fantastic - but dont think you cant go camping without one. An esky is generally colder than a fridge, far cheaper and you have to buy a shed load of ice before you come close to the cost of a fridge - and thats before you take into account servicing (I've had mine serviced twice in 3 or 4 years - but I give it a flogging), replacing batteries (they dont last for ever - most people are doing well to get 2 years out of a 100ah battery with an average cost of $350 thats not a cheap excersize!).
On top of that I've had to replace my lid latches (due to poor design on waecos behalf) twice @ $16 ea and my fridge has two thats a futher $60odd I've has to spend on keeping the fridge maintained in 4 years.
Lets do the sums
waeco CF-40 (cheaper than an engel) which is a good size fridge. Not too big but should be big enough for your needs - $800 street price
protective insulating cover - $100
fridge slide so you dont do your back in trying to heave the fridge $250ish street price
100ah battery - $350
solar panel for topping battery up (80watt kit with reg) - say $400ish
Thats $1900 and thats without doing a 2nd battery setup on the car (ie your fridge battery has to be charged off 240V @ home or solar)
Even if you ignore the solar, insulating cover and fridge slide your still talking close on $1200
Now lets look at a good 60L techniice ice box - $130
hmmm $1200 - $130 = $1070
lets assume a bag of ice is $4 a bag
Now lets spend what you saved on a fridge on ice
1070/4 = 267 bags of ice. Thats a lot of ice.
Even if you buy a good $130 esky/ice box even if you decide that you want to upgrade to a fridge you will ALWAYS find a use for a good ice box. I bought a fridge before I bought a good icebox and ended up having to buy an icebox anyway.
Food for thought.
Oh BTW you can always hire a fridge tp try it out first too. You might be able to hire different sized ones (try caravan/campertrailer rentals as well as rays / annaconda for hiring) to help you choose the best size fridge. Might be a better way to go rather than buying a fridge straight up thats way too big or too small.