Battery and inverter questions

Hi Bob,
For starters, forget about any form of heating using solar snd battery, it simply consumes too much power.
You may care to read this blog by John which covers the whole question.
Electric blankets aren't too bad. They only consume about 30 Watts each when on low so even the smallest 230v inverter will handle them.

Roughly, you will need at least 200W of solar and 100ah of battery, more if you run a TV for hours at a time. Remember, you are camping, not at home!

Hi Bob,

Firstly let me state that I am not an Auto. elec. or a 12 volt expert, just someone who has been camping in both tent and caravans for more than 50 years.

If you a seriously looking at Off Grid camping, forget about heaters, electric blankets and most other electrical appliances, they just draw too much power from batteries. Yes you can get your vehicle set up with enough batteries and charging capacity, but it will be very expensive.

You can get 12 volt kettles, but they take a very long time to boil, better off using an LPG stove. As for electric blankets, a good sleeping bag with the appropriate rating and a good “thermal” blanket should be sufficient for most people. Even high country campers in the snow do not use electric blankets. However, if you must, you need to consider the continuous power consumption on your battery.

As for sizing your battery and charging system, you need to look at all the electrical appliances that you want to run, and total up their power consumption in amps, and the number of hours you want to run them, this will help you decide how large a battery/batteries you will need. You state that you have not yet got a 12 volt fridge, when sizing your battery system, it would be prudent to factor the fridge into your equation so that you do not have to add additional batteries later on. IMHO, Lithium Iron Phosphate (LiFePo4) batteries with the appropriate charging system is the way to go. They are lighter, can discharge to a deeper State of Charge (SOC) without affecting their longevity, and will recharge faster with the appropriate charger.

Next as for charging these batteries, a good rule of thumb is that for every battery Amp, you need double the watts of solar capacity. That is, for 100 AmpHr of batteries, you need 200 watts of solar capacity. Of course, solar only works during the day, and for maximum efficiency, in full sun at the appropriate angle to the sun.
A good DC/DC charger with a high amperage output (greater than 30 amps) and solar controller should keep your batteries topped up from your car or sun. You need to remember that your charging system needs to be large enough to top up your batteries while they are still discharging.

You have not indicated if you have a ute with a canopy set up, or a wagon, or a sedan. Depending on your vehicle, this may limit what size battery system you can install. An 80 Ltr. compressor fridge/freezer will draw around 4 amps per hour when cycling. So if you factor that the fridge will cycle for about 16 hours per day, depending on ambient conditions and how often you open it, 16 x 4 = 44 amps per day. Worst case scenario if the fridge was to cycle continuously, that would equate to 96 amps for 24 hours. So, you would need at least a100 AmpHr battery just for the fridge, without anything else running. These numbers will vary depending upon a number of different factors. Size and make of fridge, ambient conditions, enclosed space etc.

In the back of my wagon, I have a 60 Ltr Engel fridge, with a 40 amp DC/DC charger and a 100 AmpHr LiFePo4 battery. I carry a 290 watt folding solar blanket for when I am stationary. In my caravan, I have a 190 Ltr compressor fridge, 200 AmpHr of LiFePo4 batteries with 390 watts of fixed roof mounted solar panels. I mainly camp off grid, sometimes sitting stationary for several weeks at a time.

I hope this info has been helpful.

EDIT, I do not have an inverter. I have just read Allans response and John’s blog. Very good info there.

Macca.

Hi Bob,
12 volt lighting in a tent is a pain because you need to have wires everywhere. We just use tripple A head lamps and a couple of tiny lantern type lamps that take a single D cell, they last weeks, the baby q has its own light as does the fridge.

Heating a tent is almost impossible to do safely, just heat the bed. We do what Alan said earlier, run a double electric blanket off a 350 watt inverter and a dedicated 80 ah battery with a 100 watt folding panel.

Your fridge is the big consumer, they dont draw a lot but it is a constant consumer that you have to be constantly aware of and dont be lazy getting your panels out as soon as there is light, even if it is cloudy it will still make a bit.
Definatly worth having a suitable charging system in the car to chare your accessory batteries but dont listen to the sales people that try to sell you thousands of dollars worth of un necessary bells and whistles that you dont need.

Bob.
Unless you have a Tesla Power Wall, and sufficient solar panels, acres of them, the idea of heating a tent with 12v or 240v isn't going to happen. You can't use a gas heater in a tent, well yes you can, but it will only be the once, with eternal sleep from Carbon MonOxide emitted from the heater.
If you have enough solar panel area/wattage and a decent battery and charger you can use a 240v ac sleeping blanket as previously mentioned. The inverter can also be used to run a laptop power supply. All possible if Macca's accounting of usage/amp/hours is calculated. Ebay, Giandel 300W full sine wave for around $85 if needed. (Blanket and computer,)
The gas burner to heat a kettle will allow hot water, hot drink and easy packup in about the same time the 12v power hungry 12v kettle gets to boiling.
Running a fridge is another issue and requires it's own solar and battery unless everything is sensibly combined and allowed for and sufficient solar and battery/s to handle the lot is provided.
We all spend hundreds to save dollars.
Tv and Projector? aren't you camping? ie, getting away from it all!

Hi Bob ….. just my thoughts …
To enjoy camping you need a sound sleep. Get good quality down sleeping bags, some form of comfortable mattress, and a couple of mohair blankets for cool , not cold nights.
Some battery lights maybe, but definitely get some good headlamps.
A gas stove, with non-stick frying pan.
Comfortable folding chairs are good.
A good sized 12v fridge, with appropriate power and charging.
Solid comfortable shoes and warm and waterproof jackets and away you go.
The simplest camping you can manage will be the most enjoyable.

Cheers
Jim

Thanks everyone for your replies, all good info for me to go through!!

Thanks

Here is a simple way to gain or lose a few degrees, we have the old Barcoo style swag, basically a canvas envelope with zips, now get yourself a solar blanket to fit, in summer the shiny side down, and in winter the shiny side up, btw it is placed under the mattress, and you will be very surprised by the results

So I have been looking into Batteries and solar panels and have a few more specific questions...

So battery choices seem to be AGM or Lithium am I correct in saying
AGM are cheaper but arent as good as Lithium, but as we are only going to be using it maybe 10 times a year will an AGM battery will be good enough for us?
I have been looking at AGM batteries and there seems to be quite a difference in price from brand to brand, so are there some brands to avoid or go for?
At Snowy's they have
Zeal 105Ah - $299
Zeal 125Ah - $349

At Battery world
Century 105Ah - $399
Century 120Ah - $449

Is there a great difference between the brands?

Solar panels
I was looking at the fold up blankets as they are easier and smaller but then I was thinking that the solid panels are easier to angle towards the sun, but still think I will go with the fold up blanket.
So again do the brands make much difference?
https://ontrackoutdoor.com.au/products/solar-blankets?variant=16069399904358 I would get the 300W version as it is only slightly more expensive than the 200W one

or there is this XTM 200W from BVC for similar price - https://www.bcf.com.au/camping/power-and-household-batteries/solar-power

As I have been writing this I found this - https://outbax.com.au/voltx-12v-100ah-lithium-battery-maxray-200w-folding-solar-blanket-bundle this seems a very good combo deal including a lithium battery

Thanks

So thats Outbax off the list then haha

Looks like I need to do more digging into each specific make & model I am considering then to make sure they arent like Outbax.....

Anything with a heating element in it will chew a batteries power in 2 seconds, they're not designed for that kind of load. I run a 12v fridge and some LED lights off a 300w panel with a 135ah battery I bought in a kit from camping solar panels australiaThe trick is to just check up on your battery level each day and make sure its getting enough.

Hi,

I've been looking into a lot of batteries and solar and reading reviews and this combo seems to be a good price - https://www.4wdsupacentre.com.au/adventure-kings-200w-solar-blanket-with-mppt-agm-deep-cycle-battery-115ah-1500w-pure-sine-wave-inverter-battery-box-10m-lead-for-solar-panel-extension.html

has anyone any experience with the Kings brand or these products?

4WD Supacentre has good reviews on trustpilot in general but some bad reviews for solar panels.... I'm sure I've heard people talking about Kings products in a positive manner before though

Thanks