Our basic approach for our camper truck domestic systems is to have a dual redundancy wherever possible: failure of one component should not leave us with a total loss of capability. Click on the links to the individual systems:
Electricity
12 Volt Power
(Update note as at April 2018 – click here to see our new upgrade to lithium leisure batteries)
Modern life is now very dependent on electricity and it’s one of the crucial camper truck domestic systems. At home we take it for granted that there is always power available for charging mobile telephones, plugging in the kettle or running the fridge. So how do you achieve this in a vehicle that is not connected to the national power grid? Basically, a big battery – but it’s not quite that simple. I don’t want to get bogged down here with complicated equations and calculations, but I will give a broad overview of what I have found to be very effective in my previous vehicles and Cuthbert, the truck we live in today.
Most modern gadgetry can be charged from a car cigarette socket, i.e. from the vehicle’s 12 volt battery. However the vehicle battery could soon be flattened if you try to run too much from it while the engine is not running. The solution is to fit another battery to run your gadgets and other systems i.e. the fridge, cabin lights etc. I will call the vehicle’s original battery the ‘starter battery’ and the second battery the ‘leisure battery’.
Charging the leisure battery. The quickest and easiest method is to connect both batteries together while the engine is running and disconnect them when the engine stops. This allows both batteries to charge from the engine while it is running, but preserves the charge in the starter battery for when it is needed to start the engine. However a few technical issues can arise. Here is a very ‘dumbed down’ explanation of how the battery is charged.
Using the battery removes Amps from the battery and charging it puts the Amps back in. To make the Amps flow into the battery, you need to raise the voltage applied to the battery. However, if you raise the voltage to high, the flow of Amps will be too great and you can boil and destroy the battery. If the voltage is too low, there will not be enough flow of Amps; the battery will not charge properly and will eventually degrade and fail.
The alternator is the device on the engine that produces the electricity; they come in different sizes, or more correctly, different power output capacities. The power output capacity is normally stated in Amps, i.e. 70 amps or 140 amps. If you attempt to draw more power from the alternator than it can produce, the output voltage of the alternator will drop and the batteries will charge more slowly (if at all).
There are some differences between the systems on older and new vehicles:
Older vehicles: if you connect the leisure battery to the starter battery as soon as the engine starts, the load may exceed the alternator’s capacity, which can reduce the effectiveness of the charge to the starter battery and the leisure battery. It is therefore quite common for the relay that connects the two batteries to have either: a 5 minute time delay after starting; or a system that senses the voltage and only connects the leisure battery after the starter battery has received an initial charge.
Modern vehicles: these use the Engine Control Unit (ECU) to control the charging of the battery. The ECU often produces a high voltage (about 14.5V) just after engine starting (this gets a large flow of Amps into the battery to replace the Amps removed during the start) then reduces the voltage after about 5 minutes to a more normal charging voltage (13.8V). A modern ECU controlled vehicle can often compensate for the extra load of the leisure battery, so the batteries could possibly be connected together as soon as the engine is started.
[Technical Note: the ECU controls the field current in the alternator to produce the desired output voltage from the alternator. In older vehicles, the field current is simply driven by the voltage of the vehicle’s electrical system to regulate it at a constant voltage]
Where to install the leisure battery. As we have seen above, the charging is all about applying a high enough voltage to get the Amps flowing. If we can put the leisure battery next to the starter battery, the cables will be short and efficient. However, there is rarely enough space next to the starter battery for a leisure battery and it has to be mounted elsewhere, often some distance from the starter battery. The longer wires required to connect the two batteries will result in a voltage drop between the batteries and the leisure battery therefore never gets a voltage as high as the starter battery. This in turn leads to fewer Amps, therefore less charge and eventually premature battery failure.
There are a few things that can be done to improve this situation:-
- Using very large cables to connect the two batteries (the larger the cable, the lower the voltage drop).
- Raising the output voltage of the alternator (this can be done by playing with the field current input) to compensate for the voltage drop to the leisure battery. I would not recommend this as you are then driving your vehicle’s electrical system at a higher voltage than it was designed for and could lead to premature failures.
- There are electronic systems that can be connected between the two batteries that cleverly raise the voltage from the starter battery to the leisure battery to solve this problem.
- Adding a solar charging system (I believe this is the best solution).
A large solar panel (anything over about 10 watts) should never be connected directly to the battery as it could boil the battery. It must only be connected through a solar charging controller. A ‘12 volt’ solar panel will typically produce up to about 17 volts in full sunshine.
Due to the higher voltage, this can be used by the solar panel charging controller to top the leisure battery up to a higher level of charge than would be achieved with the ‘battery to battery’ connection. This means that after the engine has started, you can get an initial high volume of Amps into the leisure battery from the ‘battery to battery’ connection (about 40 to 50 amps), then once the charge is almost complete (and the voltage from the ‘battery to battery’ connection is not quite enough) the solar system will finish off the charge to 100%. The other advantage of this configuration is that if you want to park up for the day and not drive, the solar will still recharge your leisure battery.
Solar capacity: In light of all this theory, how big do the bits need to be? In my Toyota Fortuner I used a 110 Ah leisure battery with a National Lunar split charge relay and 30 Watt solar panel and controller to keep my 35 litre Engle fridge running continuously. This combination worked well in the Middle East where sunshine was in plentiful supply. If you are planning a northern European system you may need a little more solar capacity.
In Cuthbert we have 320 watts of solar (upgraded to 400 watts now) and a 220 Ah (upgraded to 270 Ah now) leisure battery. During one evening of running the fridge, water pumps for the shower, all the lights and so on, we use about 20% to 25% of the leisure batteries capacity (you should never use more than 50% of the battery’s capacity or you may damage it). On a cloud free winters day in northern Europe, our leisure battery is fully recharged (just from the solar) by lunch time.
One morning while camping at about 2000 m in a ski resort, I was impressed to see the solar panels producing about 5 amps, even though the solar panels had several mm of snow covering them! However, you also need to take account of the efficacy of the solar panels. On Cuthbert the solar panels should in theory produce 23 Amps (watts/Volts = Amps, 320 watts/13.8 volts = 23 amps). However in reality, with the panels mounted flat on the roof of the vehicle, i.e. not perpendicular to the sun’s rays, the most we get is around 15 amps. I would therefore always recommend fitting as many solar panels as you have space for and don’t limit yourself to the theoretical optimum amount for your requirements. (see also Solar Power Up-grade)
Cuthbert’s 4 solar panels
Another useful feature for a leisure battery is a way to force the connection between the two batteries. If you ever find your starter battery is flat, you can in effect jump start yourself from your leisure battery. It also gives you a little more battery capacity if you have an electric winch.
At the start of this section I stated that we aim to have a dual redundant system. With the leisure battery and solar charging system, we have this redundancy:-
- Starter battery is flat or fails – you can ‘jump start’ yourself from your leisure battery and run the vehicle to where you can get a replacement starter battery.
- Alternator Failure – You can run the engine on the starter battery and leisure battery to extend the range. On a sunny day the solar will probably produce enough power to run the engine electronics if you keep the load to a minimum.
In considering the leisure battery location, it is also important to consider the type of battery. When you recharge a car battery (lead acid), hydrogen and oxygen are produced which are obviously an explosion risk! There are however ‘maintenance free’, AGM, Gel and non-spillable type batteries, which should not vent these gasses if charged correctly. These would be my choice if the battery is anywhere near the living area.
240 Volt Power
There are times when you may want to use a mains powered device rather than have everything running from 12 volts. To produce 240 Volts AC ‘mains voltage’, you need an inverter. The inverter uses electronics to convert the 12 volts DC, into 240 volts AC. Cheaper inverters use a modified ‘square wave’ process that I would not recommend for modern electronic devices. More expensive inverters produce a full ‘sine wave’ output, which is suitable for sensitive electronics.
Manufacturers often advertise inverters using their peak output power, for example 1 Kw (1000 watts). You may have a 1Kw electric kettle and think that this inverter will be sufficient. However, it is important to check the small print: the inverter may have a peak capability of 1 Kw, but this may only be for 30 seconds or less; the continuous rating could be only 500 watts, which would be overloaded by your 1 Kw kettle! Also remember that an inverter will use a lot of Amps (current) from you battery. For example: a 1 Kw output from an inverter will require around 85 amps from your battery, so your battery may not last very long.
In our Toyota Fortuner we had a 300 watts inverter and only used it for charging small items like an electric shaver. In Cuthbert we have a Victron Energy Multiplus 2 Kw continuous, 3.5 Kw peak, full sine wave inverter. This large inverter allows us to use a small electric kettle, hair drier, lap-top chargers and so on, without worry.
However, the real reason for having such a large inverter is so that we can power the hot water boiler and heating from the inverter if we run out of gas (more dual redundancy in the design). Heating the hot water requires between 80 and 160 amps; we therefore specified an alternator for our engine that can supply 140 amps. To heat the water with the inverter we would need to run the engine to supplement the leisure battery’s output. In practice we can simply turn the inverter on to heat the water whilst we are driving.
Battery Charger
Another nice feature of the larger inverters is that they often incorporate a battery charger. When at a camp site with mains power available, we can plug Cuthbert into the mains supply; the inverter will charge both our leisure and starter batteries. Solar is therefore not required and we can park in the shade to stay cool. While plugged into the mains, we can also run the heating and hot water from the mains electricity, which saves our gas.
Camp sites will sometimes limit the power that you can take to say 3 or 5 Amps. Our inverter has a feature whereby we can set the level of power available from the mains supply. Should we want to use more power than is supplied by the mains, the inverter will ‘top up’ the mains supply from the leisure battery through the inverter.
I have not mentioned bulk, floating, equalising and other battery charging principles, as most people will be buying a solar controller or battery charging inverter that does all of this automatically. (See also Multi-voltage Battery Charger)
Generators
I am sure there is a place for a generator is some circumstances, but we find that the configuration we have in the Cuthbert is fine for us without one. If absolutely necessary, we can run the engine to produce power. Some points to consider with generators:-
- Weight.
- Fuel. Do you need to carry petrol as well as diesel?
- Noise. Why go to the peace and quiet of the wild to listen to the noise of a generator?
- How much you will be hated by others for item 3 above!
Gas
In Cuthbert we use gas as one of our key camper truck domestic systems, for cooking (with an oven/grill and 2 hob rings – see also hob cover lid); for the domestic hot water boiler and for the hot air heating system. The Liquid Propane Gas (LPG) is stored in two gas cylinders and is connected to a vehicle-mounted gas regulator. For safety, the high pressure hoses between the gas cylinders and regulator have shut-off valves that turn the gas off if the hose breaks or leaks. The regulator also has a crash sensor that turns the gas off if we have a crash. The system is therefore safe to use while the vehicle is in motion (the hot water and heating that is, I don’t think we would try to cook on the move!). The regulator also switches between the two cylinders automatically when one is empty.
For use in Europe, the gas cylinders are connected internally to a fitting on the outside of Cuthbert that allows the cylinders to be refilled at a petrol station using the ‘LPG fuel pumps’. This greatly eases the refilling process as no heavy cylinders need to be lifted. There are 4 types of car LPG connector, so we carry adaptors for all of these. The cylinders are fitted with shut-off valves so they cannot be overfilled and they also have contents gauges (using a float level in the tank).
Outside of Europe this re-filling system is not very widely available, so local LPG cylinders have to be purchased and with a suitable selection of adaptors can be connected to Cuthbert’s gas system.
Ventilation
Cuthbert has 3 windows, double-glazed with toughened glass and integrated sun-blinds and mosquito nets. We also have a total of 3 roof hatches: one in the bathroom and two in the main living cabin. The roof hatches are very effective to generate a good convection current flowing through the living area, which greatly reduces the temperature on a hot day.
Air Conditioning
Air conditioning for the cabin would be a nice luxury. However, considering the power that it would use, it is not really practical without power from a generator or mains electricity connection at a campsite (which we rarely have). Air conditioning was therefore not included in Cuthbert. Our ‘half-way house’ solution is a roof hatch with a very powerful electric fan incorporated. The hatch is fitted with a temperature sensor, so it will open and close automatically and start/stop the fan to regulate the temperature. The fan can be set to blow in or out of the vehicle and has a rain detector so it will close if it starts to rain. We have found this hatch to be a great help in keeping the living area cool in the heat of Africa. Also see our roof fan upgrade.
Awning
We have an awning on one side of Cuthbert to use in sunny climates. This has been good for shading the door opening and one of the windows, which helps to keep the temperature down inside the cabin as well as giving a great outside shady living space. There is an LED strip light on the underside of the awning base, which lights up the outside dining area at night (with or without the awning extended).
Water
Fresh Water
Cuthbert has a 230 litre fresh water tank, feeding a pressure controlled pump and accumulator. The pressure switch on the pump means that the pump is switched on automatically whenever any water is used. This maintains the pipes at pressure and the accumulator evens the surge in pressure as the pump switches on and off. The output of the pump and accumulator is fed through 2 filters: first a 5 um sediment filter to remove any large particles, then a 0.5 um activated charcoal filter to remove the real nasties which may be hazardous to health.
We can fill the fresh water tank from a hose pipe to a tap, but we also have a small submersible 12 volt electric pump which we have used to fill up from natural water sources. We have found that the 230 litres last us around 5-6 days for all our needs if both of us are showering every day; obviously much longer if we cut down on the showers!
Update: We have now changed our filter arangement. We now fill the tank through the 5 um sediment filter and take the water out of the tank through the 0.5 um filter. This keeps the tank cleaner and means the pump only has to push the water through one filter.
Here is a short video showing how we fill and filter our water.
Toilet/Black Water
Toilets don’t always spring to mind as camper truck domestic systems, but life would be awkward without it! Cuthbert is fitted with a Thetford C403 toilet. This features a ‘cassette’ waste tank that can be easily and cleanly removed for emptying. These types of toilets are usually used with chemicals to break down the waste and smells. However, use of chemicals means that the waste cannot be emptied into a septic tank as the chemicals would kill off the bacteria that make the septic tank work!
Given this limitation and the lack of availability of toilet chemicals in some parts of the world, we have had a SOG vent installed. The SOG vent is a small electric vent fan that is connected to the toilet’s waste tank. When the toilet is opened for use, the SOG vent draws air in through the bowl and vents to outside. The result is that: (i) any bad smells are vented outside; (ii) the increased oxygen concentration in the waste tank helps to break down the waste; and (iii) we can safely empty our waste cassette into any toilet, septic tank or long drop toilet safe in the knowledge that we are not harming the environment.
Hey… was this useful? If so, you might like to support our website costs with a donation below. Thanks 😊👍