solar cell

Keep an eye on my post on solar cell Jimbo . I got my hands on one , now looking at finding out what i have lol . Once i figure it all out ill post it here . The one i removed had the specs posted on the solar panel question . The battery was fitted behind on of the draws in the rear . The draw was shorter to alow this . The bloke I got the car off , also ran a inverter of the same set up , it was 800 watt inverter .

Jimbo it really depends on how and when you want to run the fridge.
In summer if you are prepared to change the angle of the panel during the day, you may get away with a 100w panel, but would preferably recommend 120w panel. In winter you would need a minimum of 2 x 100w panels.
For others with a 40 litre Engel or 50 litre Evakool you may get away with 1 x 80w panel and 2 x 80w panels in winter.

Thanks for that. I did a topic search but couldn't find an answer to the specific question ... what's the minimum wattage to run a 50 litre Engel?

I agree with Willem on that as I have used a 60-70 watt panel which in cloudy days does drop its output substantially. Must have generous cable sizes and as short as possible to reduce resistance & loss. Probably need 2 panels as quoted by Willem & good exposure to sun.

Every bit of advice I've ever had said never put a wet cell battery behind the cargo barrier, battery box or not. All that acid flying around in a prang is a scary thought.

Have a nice life, William. No wonder the 4x4 fraternity has to work so hard at retrieving our reputation.

I put a powerdive AGM in my camper trailer, as they are lighter and more rugged than gel cells.

GO_OFFROAD ... how do you feel about sealed batteries behind the cargo barrier?

william you are annoying me please go away

Thanks for all that advice, people. You can see I'm a complete dill when it comes to anything electrical. I think the solution is to give the solar cell idea away completely; put a deep cycle wet cell in the battery box in the camper trailer after I find out more about what "sealed battery" means; continue with the strategy of carrying as much stored electricty as I can. Thanks Roachie, yes it is a 40 litre Engel ... I was just trying to give a rough idea of our 12v requirements. Incidentally, we did manage to squeeze 10 days out of the 38 amp hour battery pack. Obviously, while we were driving we we charging it from a cigarette lighter socket behind the cargo barrier and running the fridge from another socket, constantly swapping leads and sockets over, topping up the battery pack with 240v when we had powered sites, etc etc. But as I say, ran the poor thing flat.

One last question ... if the 38 amp hour battery pack was say 30% full, how long would it take to charge it from a cigarette socket while driving at say 80-90 km hr? Is it really an effective way to top them up or were the 240v top-ups the more likely way I was keeping it going?

But then again ... seems you'd have to have that battery fairly well secured in the camper, eh? Maybe have to think about the draw bar ... all that hydrogen etc. ... and a chain and padlock ... what do motel rooms cost at Innaminka!!? :-)

Cheers Jimbo

ps keep smilin', William!

Jimbo,

Colyn Rivers has written a book on both Caravan and Motorhome Electrics and Solar. Well worth the read. I think the website is:-www.caravanandmotorhomebooks.com.au.
Word of caution. I have an electrical background and I found I had to read the books two times before I stared to understand what he was on about (Maybe I'm slow)
The general thrust of his books is that you can never charge a battery from the vehicle alternator/voltage regulator system to more than 80% (some reckon 70%). AND if you want your battery to last longer than a couple of months you never discharge it lower than 40%.
So, of your 38AH unit you effectively only ever have just over 15 AH available at anyone time.
Colyn strongly advocates Solar and gives you enough info to calculate what size Solar panels you need. Expensive though, methinks.
I'm currently investigating the ARRID TWIN CHARGE unit which the manufacturer claims will charge the aux battery to 100% and operates between 8 and 15 V DC. It uses "pulse technology" which is said to help prevent sulphation of the battery plates and extend battery life
I bought a Low Batterry Cutout by the same manufacturer at the show on Saturday.
Like most things with camping/4wding it's a compromise and dollars play a big part but if you know the limitations of your equipment and can understand a bit about why things behave as they do it helps. At least that's my opinion.

Geez, people. I think I'll go back to powdered milk! So a wet cell only charges to 70%! Crikes! I found a nice 75 amp hr Exide today for $125 ... 70% = about 50 amp hr ... I can only run it down to 30% ... that's gives me 40% between 30% and 70% ... so 40% of 75 amp hours is about 30 amp hours ... but he fridge taked 2-2.5 amps per hour ... so that gives me ballpark of about 12 hours of chillin!

Hmmm ... 2 bags of ice fills the esky ... can't always depend on powered sites where we want to eventually trek ... I'm back to the little Chinese gennie again!

Many years ago in a silly spasm of youthful spontaneity, I ran away and joined the army and found myself at RAEME Bandiana doing a Radio Tradesmans course with a poor National Serviceman electrician up the front filling the blackboard with drawings that looked a bit like city maps and asking me what the resistance would be across the thingo in the bottom left hand corner! ... that's when I ran away to officer training school ... but that's a whole new and even sadder story! :-)

Back to the sealed 38 amp hr battery box : charging it with a charger running from the gennie ... I can't get to the battery terminals so do I just hook the charger leads up to the battery box's jumper leads to charge it?

Thanks, Nigel. That's an expensive battery pack that almost bit the dust. Thanks all for your patience and great advice. Jimbo