Electrickery for camping

4x4Community 1 Electrickery for Camping

Electrickery for camping

Chances are if you have been camping for some time that you have seen friends go through the

following evolution, who knows, you might have gone through this yourself. And many of us are

somewhere on this journey ….

You go camping with friends, possibly even get to use their hand me down tent for the Saturday

night. Next week you are ALIVE, and buzzing from the experience of “the camp” …. And now you

plan your next trip. At some point you obtain your friends hand me down tent, or go buy a cheapy

at your nearest camping shop. While you walk through the store you realise you need a sleeping

bag. Thanks to Eskom we all have gas bottle at home so you are set for making coffee in camp.

No frills camping …

First camp on your own is sort of okay. But you convince yourself that if only you had the gear the

guys next to you had, then you would have enjoyed your camp so much more. Just look at his

drawer system in his bakkie, and that other guy had such good looking rig on some sort of trailer

setup ….


And the journey starts. Now you troll the camping shops. Visit every Forum to get the best

overlanding tips, for your next 3 day camp 50km from home. THREE days ! Wow, now you are going

to need some sort of a cooler box to keep the meat from going off. What !! These 4x4 camping

stores are totally wacked out. How dare they charge more than R 3 000 for a cooler box, sure that

R 250 model will do the trick.

Hoping my R250 cooler box work as well as this R 3 000 unit …

By the morning of day 2 the cooler box is no cooler than the outside air. Day two will always be

remembered for the luke warm drinks ….. Then you see the guy camping next to you has fridge ! A

fridge in the middle of the bush with no electricity nearby. Huh ??

And thus you enter a brand new world of electrical options for your camping needs.

So you buy that 12V fridge/freezer, and then find out that it needs power when you have parked

your vehicle. JIP, the salesperson “forgot” to tell you about a “dual battery setup” …. You guessed it,

you have only just started spending money. You are about to spend a lot more money on

electrickery for your camping setup.


How to power your fridge ?

The answer to this depends largely on YOUR use and requirements. There is no single answer that

works for everybody. Some need the drinks to stay cool, and don’t worry too much if the fridge is

off for some hours per day. Others keep medicine in the fridge and the power must be un-

interrupted. The following is some examples of how it can be done.

Some people place the fridge in the back of the vehicle and use an existing power point. Most of

these power points only deliver power while the ignition is switched on. The wiring to these power

points is seldom rated for long periods of use for the power demand of the fridge. The next

evolution is to install a relay and a dedicated power point for the fridge. The only benefit here is

that you now know the wire is rated for the current draw. You can also use better quality electrical

connection points.

Busy with the installation, coil still to be routed to back

Fuse and relay. Relay activate by a signal from the ignition


But this is only the start of the electrickery journey ! Having already spent a small fortune you now

WANT that fridge to be cold for the whole weekend, not only while you drive. So you start playing

camping-russian-roulette, you leave the ignition on for a few hours at a time to keep the fridge

going. And it is not long before you wake up to a flat battery !

Now you start asking questions about a “second battery”. Never in your life have you had so many

opposing ideas about a single item. You are going to encounter the following questions:

- What type of battery?

- Where must the battery be placed?

- What size cables?

- How do you charge this second battery

Most often people forget to ask how to use the power from the second battery. This typically

becomes more apparent when the next question pops up: What can I power from the 2ndbattery ?

And then a few trips later you start asking questions about solar systems.

In the following sections I will attempt to provide some insight into possible answers to these

questions.

PLEASE NOTE:

- I will mention the brands I have installed, but I will also mention some other brands as well.

This series of posts is NOT promoting any brand above any other ! Rather I will attempt to

promote technological concepts, while trying my best to explain the use of each technology

in respect to the end user requirements, and to explain it in laymans terms.

- I have multiple qualifications in electrical and mechanical engineering. But most of what I

am posting here is as a result of having paid expensive school fees along the road

ofelectrickery for our camping.

- During the last decade there have been huge advances in the various components. And by

2015 this article will need updating in terms of the latest technologies for each field … and

this need for updating will be never ending. So PLEASE read all comments in context of the

time it was written and the technology available at the time, AND in terms of the unique

needs of each end user.

- Eggie, Fluffy, Koebelwagen, Mistral, SarelF and so many more had contributed greatly to this

knowledge pool over the last couple of years – THANKS gents !


Battery type

For years our only option was “high cycle” batteries, the type that have been used as starter

batteries for decades. Then “deep cycle” batteries were added to the option list. There are now

other very expensive options as well. (With no personal experience of these alternate models I will

ask others to add information about these options)

I was going to write a nice piece about the properties of the high vs deep cycle batteries …. But the

more I researched this topic the bigger the mine field got !

For now I will just be highlighting the following very basic characteristics:

- Charge voltage –modern alternators deliver around 14V, which is high enough to charge a

high cycle battery, while a deep cycle requires about 14,5V for a full charge.

- The norm now is a battery with an approximately capacity of 100A.h.

- Deep cycle batteries are better suited for deep discharge, when compared to high cycle

batteries. Which is probably the main reason these have the market share.

- Deep cycle batteries have a unique characteristic whereby it charges slowly once discharged

below 50%. This is probably the single biggest drawback of deep cycle batteries. Once a

deep cycle battery has been discharged deeply in a camp environment you will need an

extended charge cycle to be able to get it charged properly. More about this when we look

at the charging options.

However, this magic “Capacity” of a battery is hardly the same as a 2 liter milk bottle that will always

have a capacity of 2 liter when full. According to the table below a classic six cell car battery is “full”

when it has a voltage of 12,7V. By the time the voltage drops to 12,42V the battery is only 80% full,

and 11,9V points to a charge level of 40%.


A “total discharge” is very bad for a battery and drastically shortens its life span. Thus the National

Luna fridges have a function whereby the fridge will automatically switch off at a set value to protect

the battery. The safest setting will shut off the fridge once the battery voltage drops to 11,5V. You

can push this limit by opting for the medium safety setting of 10,5V – which according to the

attached table is a total discharge of the battery, which will shorten the life span of the battery !

Battery monitors

Imagine driving your 4x4 with no fuel gauge, not knowing when you will run out of fuel.

Now imagine camping with a fridge full of drinks and meat, not knowing when your battery is going

to “die”. A “battery monitor” is the fuel gauge for your battery. From the previous table you can see

that there is a direct correlation between the battery voltage and the battery charge level. Thus a

battery monitor is just a fancy voltmeter.

The NL fridges have battery monitors installed in their fridges for this very reason.

NL also sells battery monitors. These can be used to monitor the 2nd battery voltage, or you can buy

a dual unit to show the voltages of both batteries.


Digital Volt and Amm meter to monitor power usage.

For the real techno geeks there are very fancy meters that will measure the voltages, and record the

current flow into and out of the battery.

Enough of batteries for now. I will leave it to the experts to tell us more about the current options.


Where to place the battery?

The possible answers to this question are dictated by your vehicle and camping setup.

The classic setup was to fit the 2nd battery in the engine bay. Some 4x4 vehicles are manufactured

with this in mind and have space set aside for a 2nd battery. Yet more and more vehicles don’t have

any spare space in the engine bay. With bakkies we often see the 2nd battery in the back with the

rest of the camping gear. This works, as the back is traditionally well ventilated.

Here I need to point out that traditional batteries give of highly combustible Hydrogen gas when it is

charged. As such it is a VERY bad idea to charge a battery in a closed space ! Some of the modern

batteries claim to use other chemicals and that no hydrogen is given off during charging.

If you drive a 4x4 SUV type vehicle and need to install the battery IN the vehicle please ensure you

get a battery that is totally sealed, that wont be giving off any hydrogen gas during the charge cycle.

And of course many batteries are fitted in camping trailers.

Wherever you place the

battery, please ensure

you use a proper bracket

to mount it. With

batteries weighing about

30kg it becomes a very

heavy projectile in an

accident, so it really needs

to be fixed properly.

There have been a

number of reports where

poorly designed battery

brackets tore vehicle

fenders !!

My personal recommendation is to place the battery close to where the power will be used.


What size cables?

Uhm, ja …. Bet the first installer you see will tell you that you MUST use 16mm square cable to the

2ndbattery, or even 25mm square cable if he thinks he can milk you for more money …. Thick cables

are expensive, and there is a lot of money to be made if you can convince a client to use the thickest

possible cable.

Samples of 4 mm2, 6 mm2, 10 mm2, 16 mm2 cables

The reasons for using very thick cables is to limit the “volt drop”, while the current carrying capacity

will in turn determine the minimum cable size.

On the assumption that most people reading this are not qualified electrical engineers it is best to

take a moment to discuss these terms. To keep it simple, let’s consider the flow of electricity as that

process whereby electrons move from one atom to another. For this process to occur you need a

“potential difference”, and a closed circuit. Once you have a chemical cell which provides a potential

difference, you have a situation whereby you can complete the circuit using wires and a “load” (that

item that uses the electricity). The “resistance” of the load will then determine the resultant

“current flow”. The basic terms are:

- Potential difference - volt (unit V, symbol V) - http://en.wikipedia.org/wiki/Volt

- Current flow – ampere or amps (unit A, symbol I) -http://en.wikipedia.org/wiki/Ampere

- Resistance – ohm (unit ohm, symbol R) - http://en.wikipedia.org/wiki/Ohm

http://en.wikipedia.org/wiki/Volt

http://en.wikipedia.org/wiki/Ampere

http://en.wikipedia.org/wiki/Ohm


The basic mathematical relation of these three entities is : V = I x R

In addition to this there are two more entities relevant to electrickery in our 4x4’s:

- Charge - here we use the term “A.h”, which is literally the product of the current flow and

the time it was used.

- Power – watts (unit W, symbol P) - http://en.wikipedia.org/wiki/Watt

So what does all this stuff actually mean ?

Well your 2nd battery is charged from the vehicles alternator, when the alternator has a larger

“potential difference” than the voltage of the 2nd battery. So if your 2nd battery shows a voltage of

12V and the alternator puts out 14V the 2nd battery should be charged. BUT, we need to look at the

“circuit”. This means we need to look at every connection and every piece of wire in the circuit.

Working with round numbers here – let’s say the circuit (wires and connectors) add 0,05 ohm

resistance to the complete circuit while the 2nd battery is being charged at a rate of 20A. Then we

can calculate the voltage drop in the circuit as follows:

V = I x R = 20 x 0,05 = 1V

{Note to the purists – this example use values aimed at getting the message across}

This means that of the 14V available from the alternator, the 2nd battery only “sees” 13V, since 1V

was “lost” in the circuit due to the resistance in the circuit.

Punch line : 13V is NOT enough to charge the 2nd battery ! Well not entirely true .... in practice it

means the charge current is limited, and a balance is struck between the volt drop and the charge

current. As such a 10mm square cable may well be used to charge the second battery, albeit at a

reduced current flow due to the volt drop.

And thus people started using THICK cables with lower resistance to ensure the 2nd battery “sees” a

voltage as close to the alternator output as possible. For decades this practice was our only option,

and the use of way over sized cables became the norm.

http://en.wikipedia.org/wiki/Watt


And then the deep cycle batteries entered our campsites. But a deep cycle battery needs 14,5V to

fully charge !! Thus MORE volts than many modern alternators deliver. In the next section we will

discuss how this problem was overcome. For now let’s focus on the minimum cable size.

We already know that V = I x R, in thinner cables the resistance is higher, leading to higher voltage

drops. This voltage drop causes heating of the cable. There are industry norms for the maximum

current relative to cable size to ensure the heat generated remains within safe limits. From the SABS

tables (using the worst case values) we get the following guidelines for the maximum current that a

cable can carry continuously.

Cable size in mm square 1 1,5 2,5 4 6 10 16

Current carrying capacity 11 14 18 25 32 43 57

Thus, if you used a charger that limited the charge current to 20A a 4mm square wire would be

sufficient. More about this in the next section.


How to charge the second battery

Once again there are so many options, and the optimum solution depends on your specific

requirements.

Most people start off with connecting the 2nd battery to the alternator and hoping this will charge

the 2nd battery. Depending on the exact setup you may be able to charge the battery to some

extent, but highly unlikely you will get more than 80% of the possible capacity of the system.

Remember the previous section where we spoke about the voltage drop, and the final voltage

available at the 2nd battery.

The cheap solution is to pre-charge the battery at home, with a 220V charger. Then relying on the

alternator to keep the system going for a typical long weekend trip. And this works surprisingly well

for many people. But once you take a trip of more than a few days the limitations of this approach

becomes very apparent. Then you start thinking of better systems …

The deep cycle battery is best suited for campsite use, but requires a charge voltage of 14,5V. This is

more than most alternators now deliver. This created a market place for the DC-to-DC (dc2dc)

chargers. The principle of this charger is simple, it takes the voltage from the alternator and pushes

the volt value up, by reducing the current value in turn. You now get a situation where your

alternator puts out 13V at idling, but after the dc2dc charger your 2nd battery sees 14,5V. An added

benefit is that most dc2dc chargers actually limit the charge current, thus you can now more

accurately choose a cable size that matches your installation.

Most dc2dc chargers are also “clever chargers”. The “clever chargers” monitors the charge level of

the 2nd battery. Once the 2nd battery is almost fully charged the charge current is reduced, to protect

the battery.

So while you are driving, your alternator, via the dc2dc charger, charges your 2ndbattery at 20A

(different models have different pre-set values, but this is a realistic figure).This is a very good

system and has many benefits, but still does not address the fundamental question of power while

you are parked.


As long as you are parked your fridge draws power from the battery. With an average current draw

of about 60A.h per day you need to drive at least 3 hours per day to keep the battery charged, or

find some other way to keep it charged … More about this later.

Fridge power draw

National Luna (NL) provides a current draw figure of “an average of 2,5A” per day for its 52 liter

Weekender Twin unit. Basic maths says 24 hours times 2,5A = 60A.h -

http://www.nationalluna.com/weekender52.htm

BUT, NL briefly mentions “..consumption is measured in a controlled environment ... Actual power

consumption may vary ...”. Actual tests show a current draw of 5 to 6 A. Due to the on/off cycles

the average of 2,5A is possible in moderate climates. During summer in Kgalagadi or Namibia, with

day temperatures of more than 40 degrees Celcius, and night temperatures mostly above 30

degrees Celcius the fridge hardly ever switch off !! At 5A for approximately 20 hours you suddenly

need 100A.h to power your fridge !!

The actual power draw of your fridge will depend on many factors:

- Insulation – the quality of the insulation has a big impact on the power draw.

- Where the unit is installed – A unit installed inside an air conditioned SUV will draw a LOT

less power than a unit stuck in the back of a super hot canopy.

- Use – Opening the fridge too often increased the cooling load, and thus increase the power

draw.

- Loading of goods – Try to load cold goods into the fridge, or load the goods when you can

use mains power to cool it down, thus saving your battery capacity.

- Operating temperature – The colder the thermostat setting of a fridge, the higher the rate of

heat flow through the insulation.

Never over look the most obvious though – use the 220V in the camp site when available.

What is a “relay” ?

When switching a circuit on or off, a spark is generated at the switch. This spark actually burns away

the switch contacts over a period of time (number of uses). The solution to this problem is to limit

the current that flow through the switch – but the current flowing to the load is a constant. As such

the circuit is now split in two:

http://www.nationalluna.com/weekender52.htm


Diagram of a relay

Typical auto relay

Think of this as the electrical circuit for a set of spot lights. By switching the spot light switch, you

are passing a small current through an electromagnetic coil, this closes the heavy duty switch

between “30” and “87” and power is now sent to the spot lights. The contact point numbers used in

the illustration are above are the standard numbers found on relays.

The current flow will determine the type of relay to be used. For spot lights and other small items

standard relays are used. For connecting two batteries a much higher current flow is allowed for

and a heavy duty cole hersee type relay is used.

N L

Signal

Switch

L To “Load” N

86 85

87 30

Fuse


Colehersee relay

Relay and fuse box for spot lights, air horn, radios

The benefit of a relay is that it will function automatically and

no additional user input is required. That said, there are still a

few users that want full manual control. They would then use a

typical “marine switch” to connect or disconnect batteries.


What to power from the 2nd battery ?

What do we use cell phones for now ? “Phoning” is last on a very long list of functions.

In the same way we start with a 2nd battery system to power the fridge. But once we have power,

we realize that it could:

- Charge the cell phones

- Charge the iPads

- Charge the laptops

- Charge the camera batteries

- Drive the compressor

- Power an electric blanket for winter camping

- LED lights

- And the list just keeps on getting longer and longer …

To manage this host of devices you will need a well planned power distribution setup. Jip, you have

now migrated from simply powering your fridge to becoming your own Escom !

PLEASE NOTE:

The 12V battery and all the cabling you are about to install DOES have the

potential to burn your vehicle to the ground if done badly !

MOST manufacturers void your warrantee once you have these electrical

installations done !!

DON’T play with this if you don’t know what you are doing. This article is

aimed at helping you to understand what a decent system should have in it.

This is not a DIY training kit !

When doing a power distribution system the safety of this system is determined by:

- Size and placement of fuses

- Wire sizing

- How wires are run

- Connections


FUSES

Install a 100A fuse close to the 2nd battery in the main positive wire going to the distribution box. In

the distribution box plan your layout and provide appropriate size fuses for each circuit, ie a 5A fuse

for the LED light circuit that will only be using about 1A, or a 15A fuse for the circuit that will power

the fridge.

WIRE SIZING

With each circuit properly planned, you will know the expected current draw for that circuit and can

use the optimum wire size. The only downfall of oversizing is the impact on your budget, but under

sizing cables are to be avoided !

RUNNING THE WIRES

The fuses provide a measure of safety in the event of a short. But prevention is better than cure.

Run the cables in sleeves or trunking to protect it, and to avoid electrical short circuits. The use of

cable ties greatly assist with keeping wiring neat and preventing it from chaffing through, potentially

causing short circuits.


CONNECTIONS

We go through all the effort of using correctly sized cables to keep voltage drops to an absolute

minimum. Yet, one bad connection can cause more of a voltage drop that all the wires. And such a

bad connection has the potential to generate heat and be the cause of an electrical fire!

Electrical connections very often make use of “lugs”. Proper connection of the wire to the lug can be

done in the following ways:

- Solder – Insert the wire into the lug and solder it. However, a bad solder joint can cause a

“dry-joint” which leads to a volt drop, which causes heat build up, which can melt the solder

and the joint can become undone ! This is probably the lead cause of failure of joints.

- Crimping – using a proper crimping tool you can ensure a proper connection of the wire to

the lug. The photos below shows two decent crimping tools. Do NOT try to use a pair of

pliers to crimp a lug !

- Crimp and solder – I prefer to use a proper crimping tool, and then to also solder the joint.

Definitely a belts and braces approach.

- Once the connection has been made, use some “heat shrink” to achieve a proper finish. A

4x4 fitment centre that use “insulation tape” wont ever touch my vehicle.

Quality crimping tools

Heat shrink to finish off the connection


LUG SIZING

Lugs have two dimensions:

- The whole diameter – the diameter of the bolt or screw that will hold the lug in place.

- The wire size – this dimension refers to the wire size that is to be used with that specific lug.

Thus a 6x4 lug will be connected to a battery terminal with a 6mm bolt, and will accommodate a

4mm square wire. Using the correct size lug is important to achieve an optimum connection.


Solar systems

You have now almost come full circle. You bought the fridge for your next 3 day camp. You now

know the basics of where your 2nd battery can be mounted. You even know the basics of the wiring

and fuses to distribute your new found power for other devices ….

And suddenly you find that the fancy dc2dc charger no longer can store enough power in that

stupidly small 100A.h battery to drive the fridge, cell phones, laptops, camera batteries, etc etc …

And driving for hours on end each day to keep all these devices charged is taking the fun out of your

three day break away.

Time for the next step on this electrical journey – a solar system. After all this will keep that battery

going and everybody can sit around the camp fire with their faces pointed directly at their individual

electronic gadgets. So what are your options with solar:

- Foldable – You get a kit that folds up and packs away to about the size of a brief case. Nice.

Minimal packing space. And when you need it you place it out on the grass and charge your

battery. Downsides being that it only works when you have actually packed it out, ie it does

not help you when parked out near a watering hole taking some photos, and when you get

back to camp late in the afternoon there is not enough sunlight left to really charge the

battery. And if you place it on the ground the neighbours kids ride over your panel with

their bicycles. And at about R7 000 for such a fold up panel you want to wring their little

necks for breaking your panel !


- Roll up panel – very much the same concept as above. Just cheaper and it rolls up to the size

of a large drum.

- Solid panels – An 80W panel is about 1000x700mm. VERY uncomfortable size to pack away,

this is the reason people consider the first two options. To reduce the packing space people

use two of 50W panels with hinges, now the panels can “fold double” drastically decreasing

the packing size. This is actually the same as the first two options, just much cheaper. The

main drawback remains, solar panels that are packed away don’t charge any batteries. Solar

panels only work when in the sun ! (nothing worse than killing a battery in Kgalagadi, while

your fancy solar system is packed away inside your vehicle ….)

- Permanently mounted solar panels – the ultimate solution is to have solar panels

permanently mounted on the roof of your 4x4. This way it can charge the battery any time

your vehicle is parked in the sun.

Solar panels charge your battery via a “regulator”. There are basically two types of solar regulators:

- Shunt – Your solar panel will have about

16V worth of potential energy while

charging, while the battery needs

between 13,5 and 14,5V to charge. The

shunt regulator “throws away” the extra

volts. Thus reducing the potential

power you can get from the solar

panels.

- MPPT (Maximum Power Point Tracking)

- Think of this as a reverse dc2dc

charger. It reduces the potential 16V to

the required 13,5 to 14,5V, and

increases the charge current by the

same ratio. Thus ensuring the maximum

solar power is delivered to the battery.


Thanks to a number of specialist suppliers we now have access to some stunning camping

equipment. Even a dc2dc charger that also has a MPPT solar connection point. These units are

known as “dual chargers”.

The Ctek 250 S set the standard for dual chargers. It has a dc2dc charge rate of 20A, high enough for

a fast charge without damaging the battery. But it also has a built in MPPT solar charger for your

solar panels. This unit is fully automatic. As soon as you start the engine the Ctek senses this and

the dc2dc charger starts about 5 seconds later. When you switch off the engine the Ctek will

automatically switch over to solar charging.

HcDP now also has some dual chargers. Some need manual switching, while others switch over

automatically. (I strongly recommend the models that switch automatically between alternator and

solar)


Dual battery system

Having covered the basics in the previous “chapters”, it is now time to apply this information to select components for a dual battery system.

Let’s do this for a bakkie with the battery in the back of the vehicle and with a full power distribution system. This is how it was done 2 decades back:

Fuse at the 1st battery, then a basic heavy duty relay, and some 16mm square cables to charge the second battery.

Due to the high voltages required to charge modern deep cycle batteries this approach has now fallen by the way side. We now use dc2dc chargers, as follows:

This way we are now SURE the charge voltage is high enough to fully charge the 2nd battery. Since the dc2dc charger limits the charge current we can now use a 4 or a 6mm square wire from the front to the back. Note how the dc2dc charger is located close to the 2nd battery.

- + - +

Fuse

Colehersee relay

- + - +

Fuse

DC to DC charger

13,8V 14,5V


But you want to camp without having to run the engine, thus you need to add solar :

With this setup the alternator can charge the battery while you drive. And while camping the solar panel can charge the battery.

If you were to use a Ctek or HcDP dual charger your setup would look like this:

Okay, so your charging circuit is sorted, now let’s look at the distribution from the second battery (include a fuse AT the battery in the positive lead):

- + - +

Fuse

DC to DC charger

Solar

panel

Solar Regulator

- + - +

Fuse

Dual charger

Solar

panel

- +

5A

10A

20A

20A

Lights circuit

Laptop charging circuit

Fridge circuit

Spare charging circuit


Combine all of this and you may well have a “dual battery system” that looks something like this:

5A

10A

20A

20A

Lights circuit

Laptop charging circuit

Fridge circuit

Spare charging circuit

- + - +

Fuse

Dual charger

Solar

panel

My ideal system (for OUR use):

6mm2 from 1st battery to dual charger

Fuse AT 1st battery

Dual charger

100A.h Deep Cycle battery

10mm2 to distribution box (overkill)

Fuse box and various power outlets ….

Electrickery for camping

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