camping off-grid - power, batteries, solar, fridges

see also:

• solar power for camping
• solar regulator / controllers for solar panels for camping
• 12V batteries and battery boxes
• DC-DC charging of auxiliary batteries using your car's alternator
• electrical cable sizes for DC use and 12V batteries
• electricity in Australia
• looking after your batteries
• overnight hiking camping checklist (for hiking during daylight to a camp site, not hiking in the dark!)
• overnight ultralight bushwalking shelters and equipment
• going off-road / 4WD
• taking the Subaru Outback off road
• tips for camping in the rain
• how to reduce your risks in lightning storms
• treating water to make it potable / drinkable
• shelters and tents for car camping or alpine 4 season use
• car over-heating or losing coolant
• Victron's pdf on electricity, wiring, batteries, etc

• one of the main issues when camping off-grid for an extended period is power supply to run fridges and other devices
• for short periods, lithium ion batteries or lead acid battery may suffice but for extended periods these need to be re-charged and one does not want to rely upon running the car to re-charge them.
• caravans often have gas powered fridges

• 12V battery - usually 100Ah deep cycle to fit a standard battery box (preferably LiFePO4)
  • NB. these CANNOT be used to jump start the car!!
• battery box with voltmeter and various plugs including at least 2x Anderson plugs (these are bidirectional 50A)
• Anderson plug cables to your devices with an inline fuse in the system to avid short circuits damaging your battery or starting a fire
  • optionally have Anderson plug cable with cig lighter female port on other end (or two of them)
  • optionally have one plug to two Anderson plug cable
  • optionally an amp meter with Anderson plugs on either side to measure voltage, current and total power used (or supplied) through the cable
  • optionally a connection from boot to externally mounted Anderson plug at rear of car to provide power to your tent, etc via an Anderson plug extension cord
• battery charging systems such as:
  • 240V AC battery charger for your type of battery (usually 15A or 25A)
  • DC-DC charger if charging from your car's alternator
    • need to connect this to the car battery with an inline fuse
    • need to connect to auxiliary battery via cable with Anderson plug
    • may need to connect a wire to the car ignition system
  • solar panel and solar regulator (this may be included in your DC-DC charger) with Anderson plug
    • see also solar regulator / controllers for solar panels for camping

• general rule:
  • 12V best for small systems with less than 300Ah
    • easier and safest to use
    • plenty of accessories available
    • can be charged from your car alternator using a DC-DC charger
    • not great for high wattage devices over 500W unless you have a 200A 200-300Ah 12V LiFePO4 battery and a suitable AC inverter
  • 24V may be best for RV's but only where you need more power
    • possibly cheaper as has half the amp requirement and thus less copper needed than 12V but you do need more voltage converters and troubleshooting and maintenance is more complicated
    • more efficient as less voltage drop across long wires
    • can still use 12V accessories via a 24 to 12V converter and these generally have 90% efficiency
    • BUT solar panels need to be at more than 24V to charge them hence you may need group parallel panels into pairs of series panels to overcome shading issues etc whilst still giving the needed voltage
    • cannot be charged via your usual 12V car alternator
    • still relatively safe as under 30V so 24V can be a sweet spot for larger more demanding systems BUT THE BIG ISSUE is complexity of managing BOTH 12V and 24V and cost of DC regulators to manage this and dedicated 24V gear
    • you need to connect two 12V batteries in series to get 24V - not all 12V batteries allow that
  • 48V is best for solar power homes or cabins
    • when you need lots of watts, 48V is much better at achieving it but runs a major risk of electrocution

• see electrical cable sizes for DC use and 12V batteries

• see car fridges for camping

• there are a variety of components required

• this is to charge your battery before you leave home or if you have access to AC power
• in general, 2000-3000W AC inverters will need to be grounded, well ventilated, secured, have in-built safety switches, and should be well away from gas cylinders as they can arc when being connected
• you will need 0AWG cable with fuse (250A for 2000W, 350A for 3000W) to connect AC inverter to your battery
• you have the option of either:
  • separate AC LiFePO4 battery charger and separate AC inverter/UPS power unit
    • this is the easiest and cheapest way to go for most campers as they can leave the charger at home to save space and they may not even need an AC inverter
    • 12V Lithium charger such as:
      • eg. Victron IP65 BlueSmart Charger 25A 1.9kg ~$AU220
      • eg. Victron Blue Smart IP22 Charger 12V 30A 1.3kg ~$AU211
    • Pure Sinewave 12v-240V AC inverter with UPS such as:
      • get one with a built-in AC RCD/Safety Switch:
        • eg. HardKorr HKPINVAC2000 2000W 187A 5.1kg $539 but need to also buy 0AWG, 250A fused cable, and, optionally including a IEC-C19? AC cable to power it for UPS function
          • Eco mode allows the inverter to run more conservatively, with a draw of <0.2A, when the inverter doesn’t have a detected output. When the function is not enabled the 2000W inverter will draw up to 1.3A when on standby with the 3000W drawing up to 1.6A. Allows current through the inverter when it detects more than 50W and stop output when there’s less than 50W.
        • eg. https://itechworld.com.au/products/2000-watt-pro-pure-sine-wave-inverter-with-ats-and-rcd iTechWorld 2000W with ATS and RCD $599 - needs to be grounded
    • as an example see this set up in a 4WD ute: https://www.youtube.com/watch?v=cNGDdiqMyZ4
  • combined AC LiFePO4 battery charger and AC inverter/UPS power unit
    • you have these plugged into AC power and it will keep your lithium battery charged while providing AC output to your devices
    • if AC power supply fails, the UPS function immediately kicks in to keep your computer or other AC powered devices running from your battery
    • this is really best for off-grid residences, offices or for caravans
    • eg. Victron MultiPlus Inverter/Charger 500-2000VA models available in 12V, 24V or 48V versions
      • https://www.energyeco.com.au/products/victron-multiplus-inverter-charger-230v-500va-1600va 15.5kg
        • a 12V 2000VA model will cost around $AU1250 and you will probably want some add ons to monitor it such as VE-USB interface, etc

• fast charge, high capacity but heavy and expensive
  • eg. 200-300AH LiFePO4 battery (~13kg) with BMS with 200A discharge rate to allow for 2000W AC inverters but too big for standard battery boxes - best for caravans, etc.
• fast charge, medium capacity
  • HardKorr Heavy Duty Battery Box $AU219 3.2kg
  • 25A battery charger designed for LiFePO4 with Anderson plug connection modification $AU250-300
  • 100Ah LiFePO4 battery 12kg $AU400-800 but this will only allow up to ~600W AC inverter power output
• slow charge, low capacity, light weight and compact power station
  • eg. Companion 40Ah Rover (~7kg) but only 5A charge rate which limits solar charging
• see 12V batteries and battery boxes

• DC-DC car charging
  • newer cars will not generate enough voltage to charge an auxiliary lithium battery so you will need to use a DC-DC charger wired directly to the cranking battery (these will have a built-in voltage sensitive relay (VSR) or similar mechanism to stop draining your car battery when the car stops) which will be powered by the alternator
  • a 25A charger will suffice for batteries up to 200Ah, however a 40-50A charger will be best for 100-300Ah batteries
• see DC-DC charging of auxiliary batteries using your car's alternator

• see solar power for camping
• see also solar regulator / controllers for solar panels for camping

• MC4 connectors
  • weathersealed single wire connectors usually used on solar panels
• Anderson 12/24V socket
  • a specialized socket designed to handle a high, continuous load which allows charge from your car battery or solar panel to flow to your accessory battery in dual battery systems and hence can be used to connect car to caravan
  • can also be used powering high-draw 12-volt accessories such as fridges and air compressors
  • they come in different current sizes eg. 50Amp
  • tow bar extension wiring:
    • https://www.australiandirect.com.au/Battery-Systems/Wiring-Connections/KA8M2.5A2A 2.5m with plugs $25
• Merit 12/24V plugs
  • similar to cigarette lighter plugs BUT smaller in size and have the advantage of a superior rugged construction and higher current carrying capability
  • can be converted to cigarette lighter plugs

• these are important particularly if you need to run higher current draw appliances such as air conditioners, heaters and microwaves
• they can also be used to re-charge your batteries if the solar is not adequate
• make sure you get one with pure sine wave inverter to give clean AC outputs that won't damage your electronics
• also check how noisy it is as they are perhaps the most hated accessories at camp grounds due to their noise (as well as exhaust fumes)
• some have parallel stacking capability to combine units for greater power output
• these will generally consume 0.4-0.45L of petrol per 1kWh electricity output at full load output (ie. enough to power a 1000W appliance for 1hr or charge a 100Ah LiFePO4 battery from 80% discharge - a 25A charger draws 380W at peak)
• noise levels are typically measured in decibels (dB), usually at 7 metres (23 feet) from the generator
  • inverter designs are generally quieter but still generally 50-60dB, and at the lower end of the noise level when run in ECO mode (usually 1/4 load)
• most 2KW (ie 2KVA) models weigh 20-25kg, have tank size of around 4.5L (the Honda EU22i is only 3.5L) and can run for 8hrs at 50% load
• NB. the power output are given as 2 figures - maximum and actual rated which is a little lower
• some can connect two in parallel to give twice the output
• examples:
  • Ryobi RIG2000PCB 2000W Petrol Digital Inverter Generator $AU999 - 24.4kg 2 x 15A sockets and 2 x USB outlets
  • DeWALT DXIG2200 2200W/1800W Inverter Generator $AU1299 - 22.5kg, 50-54dB, 1x 15A socket, 1 x 12V cig; can connect two in parallel to give twice the output
  • Full Boar SD2200I 2200W Inverter Petrol Generator $AU798 - 21kg, 61db
  • Yamaha EF2200iS 2200W/1800W - 25kg, 57–59dB
  • Yamaha EF1000iS 1000W/900W 1 KVA Silent Inverter Generator $AU1299 - 12.7kg, 47-57 dBA/7m

• Kowwer P1 100W Mini Generator for hikers
  • uses a hiking isobutane gas cartridge - 230g gives ~1kWh electricity at 100W (peak 130W); 3 way hose allows simultaneous gas cooking;
  • 58Db; built-in small solar panel; 2x 2A USB output; 4A USB-C output; 8A 12V output
  • 4.96lbs 9.64“x5.31”x6.3“ high; 2.25kg; 245x135x160mm
  • Pro version is 300W with peak 390W
  • https://www.kowwer.com/ will be launched on Kickstarter in 2024

• https://www.deepcyclesystems.com.au/product/12v-basic-off-grid-system/ $AU3999
  • Victron 12v 1200w pure sine wave phoenix inverter
  • DCS 12v 200Ah 2.4kWh lithium battery storage
  • 31.5A Votronic solar controller
  • Trina solar panels (2 x 310w mono)
  • Victron Battery Protect (low battery voltage protection)
• https://www.deepcyclesystems.com.au/the-dcs-off-grid-survival-guide-for-modern-day-living/
  • 333Ah 48V 16kWh dual lithium battery system (2 x DCS PV 10W LFP batteries which provide total 15kW continuous load) = 198kg, $AU17,999 for batteries alone (cw 900kg of lead acid cells)
  • Selectronic 7.5kw SP PRO solar controller
  • Fronius 8.2kw Primo inverter
  • 10 ~ 12kw of solar PV panels - should provide around 19kWh even on the most cloudy days in lower latitudes and average winter evening usages for a house runs at around 10kWh.
  • +/- 5kVa diesel backup generator
• Sungrow LiFePO4 2021 tech floor batteries¹⁾
  • each “unit” consists of “modules” internally connected in series to increase voltage, capacity and power outputs, each of which is a 33kg 64V 3.2kWh LiFePO4 battery
  • power outputs below are for DC outputs, all at 30A max continuous charge/discharge with 42A peak;
  • can combine up to 4 units in parallel to increase capacity
  • Sungrow SBR096 unit:
    • 3 modules; 192V 9.6kWh; 6.57 kW peak / 5.76 kW continuous; 114kg; ~$10,200; roughly equates to eight 100Ah 12V LiFePO4 batteries
  • Sungrow SBR128 unit:
    • 4 modules, 256V, 12.8kWh; 8.76 kW peak / 7.69kW continuous; 147kg;
  • Sungrow SBR160 unit:
    • 5 modules, 320V, 16.0kWh; 10.95 kW peak / 9.6kW continuous; 180kg;
• Tesla wall batteries
  • to use these for backup power will require modifications to your switchboard
  • Tesla Powerwall 3
    • 13.5kWh usable capacity; uses older and potentially more dangerous Nickel-Cobalt-Manganese (NCM) or Nickel-Cobalt-Aluminum (NCA) li-ion technology instead of LiFePO4; fully integrated Tesla hybrid inverter (up to 20kW solar PV input), 130kg; ~$12,999
    • Compared with Tesla's Li-ion batteries, LiFePO4 tech is safer as it does not suffer from the explosion risk of same overheating and thermal runaway that li-ion batteries have, and lasts for more 2-4x as many cycles of charging, although is more bulky

• see wiring up a campervan for 300AH/day usage via solar
• battery packs wired in parallel (reds to reds and blacks to blacks)
  • red wire of 1st battery to main fuse which connects to shunt which connects to distributor box
  • black wire of last battery to shunt then to distributor box
• distributor box (eg. Victron Lynx Distributor)
  • earth wire to chassis ground
  • red and black wires to the DC fuse box in the AC-DC distribution panel to supply DC outs
• inverter charger (eg. Victron Multiplus Inverter Charger 3000 W 12V)
  • red and black to distributor box DC in
  • earth wire to distributor box earth
  • 3 wires (active, neutral, ground) from Shore power to AC in
  • 3 wires (active, neutral, ground) from AC out to AC-DC distribution panel with a breaker
  • thus the inverter charger can:
    • combine amps from Shore power AC (eg. 30A) with the amps from the batteries if usage exceeds the Shore Power amperage
    • if power usage is less than the incoming Shore Power AC, then unit can use this to charge the batteries via the same cable to the distributor box
    • provide AC outlets
• MPTT solar controller
  • red and black “battery wires” to distributor box
  • earth wire to inverter charger earth
  • red and black “PV” / solar wires” to solar circuit breaker
• solar panels are wired in series (or 4S2P pending requirements) and wired to a circuit breaker which is used as a disconnect

• capturing methane produced from food waste and using it for cooking is a developing concept which may be attractive for many who live off-grid
• see https://www.sciencedirect.com/science/article/abs/pii/S0959652619301350#! which suggests a household could generate enough methane for average 38 minutes cooking per day (it may take 4 years to pay for itself at 2019 gas prices), and in addition, generate compost and fertiliser

• NB. the following are my theoretical calculations - see an expert before embarking upon such a system!

• there are turbines available for fast flowing streams (> 1m/s)
  • https://www.energymatters.com.au/ampair-100watt-12v-micro-hydro-water-powered-generator-p-679.html
    • 100W 12V turbine in > 400mm deep stream will give 8A 12V 96W output if stream at 3.5m/s and 5A 12V 60W at 2.5m/sec
    • 10kg

• this is relatively easy just need a pipe from the waterhead source and a pico hydro-electric turbine and this can produce a continuous 230V AC output
• 750W turbine requires 18m waterhead and a flow of 5-8L/sec using 75mm pipe and may cost $15000-25000 to buy and install
• eg. https://www.micro-hydro-power.com/pico-hydro-turbine-generator/

• most people don't use their solar power when it is generated during the day
• storing your solar power is problematic, one solution is expensive batteries as above, another potential solution for those whose properties reside on a steep hill is a pico hydro-electric system
• a large water storage is held at BOTH top and the bottom of the property
• during the day the solar power drives the pump to send the water from the bottom tank to the top tank
• at night as required, the water can be released from the top tank to pass through turbines to generate hydro-electric power
• the amount of hydroelectric power able to be generated in this way is:
  • Change in potential energy of water = mass water x g x height difference
  • Power assuming 100% efficiency = change in PE per second
  • thus Power in Watts = efficiency factor x density water x water volume flow rate x gravity constant x water drop in meters
    • efficiency factor is 0-1 (pico turbines are generally rated at 70%)
    • water density = 1000kg/m³
    • water volume flow rate in m³/sec
      • can use the Hazen-Williams equation for a gravity fed pipe system:
        • velocity in m/s = k * C * R0.63 * S0.54
          • C = roughness coeff of pipe = 100 for cast iron, 110 for concrete, 140 for copper, 150 for plastic
          • R = hydraulic radius in m = the proportion between the area and the perimeter of your pipe = radius / 2
          • S = Slope of the energy line (frictional head loss per length of pipe). It is unitless, but sometimes expressed in m/m; = height drop / pipe length
          • K = Conversion factor dependent on the unit system (k = 0.849 for the metric system)
      • water volume flow rate = pipe area x velocity water
    • gravity constant = 9.8 m/s²
    • thus combining the above gives: Power in Watts = efficiency factor x 4444 x r³ x C x height² / pipe length
      • example:
        • 30m drop with a 45deg slope requires pipe length of 30/Sin45 = 42m, assuming 75mm plastic pipes would result in flow rate of 0.58m/sec = 0.00256m³/sec = 9.2m³/hr = 9200L/hr
          • power assuming 40% efficiency = 300W
        • 30m drop with a 60deg slope requires pipe length of 30/Sin60 = 35m, assuming 100mm plastic pipes would result in flow rate of 0.94m/sec = 0.0073m³/sec = 26.2m³/hr = 26200L/hr
          • power assuming 70% efficiency = 1500W
          • to get this 1500W for 4 hours each night you need a 100,000L top and bottom tank
          • assuming you can get 8 hours solar panel output each day, you would need to generate around 1500W*4/(0.7*pump efficiency factor) of solar power
            • assuming your pump solar power system is 40% efficient, this gives a total daily solar energy need of around 21kWhrs or 2700W for each of the 8hrs daylight
    • HOWEVER, you do need:
      • a top and bottom tank with sufficient capacity to provide the flow rate required for the desired time period,
      • a pump output and return pipe optimised to use the expected solar power output to return the water to the top tank

• you can get cheap Chinese pole mounted small units (excl. pole or MPPT controller) at:
  • 800W output which are about 1m diameter in lantern style, 11kg for around $AU500
  • “3000W” but actually more like 1500W 1.25m diameter 5 blade propeller style for around $AU400
    • starts at 7kph, at 20kph you get only 150W, you need 50kph to get 1500W!
• for larger systems, these require a rural property of at least 1 acre and mounted on a tall tower
  • costs start around $AU28000 for a 3.3kW system and require specialist installation and annual maitenance

• cutters
  • Hakko-CHP-170 Micro Cutter - for trimming smaller wires, etc
  • Triplett TT-242 CablCut Multi-Wire Copper Cable Cutter (but best use a dedicated stripper instead of the one included on this)
• strippers
  • Klein Tools 11063W Wire Cutter / Wire Stripper for 8-20 AWG Solid and 10-22 AWG Stranded Electrical Wire
  • Jokari 10270 Secura Cable Stripping Knife for All Standard Round Cables
  • IRWIN VISE-GRIP Wire Stripper
• crimpers
  • IWISS AP-50BI Cable Crimper for Copper Cable Lugs from 8-2AWG
  • Titan 11477 Ratcheting Wire Terminal Crimper Tool for Insulated Terminals
  • Klein Tools 1005 Cutting / Crimping Tool for 10-22 AWG Terminals and Connectors, Terminal Crimper for Insulated and Non-Insulated Terminals
• soldering iron
  • Hakko FX601-02 Adjustable Temperature Controlled Soldering Iron
• AC/DC current clamp meter
  • NB. the clamp current only works on a single line - you will get a net zero result on power cords with active and neutral or pos and neg wires
  • most also have a thermometer to 1000degC
  • Klein CL390 $AU120 on Amazon
• multimeter
• insulated ratchets for socket sets to work with battery terminals without shorting them
• see https://www.youtube.com/watch?v=qbg4k0Oh55c