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Battery Types: Vehicle Versus Accessories
Your vehicle battery, or preferably batteries, are there first and
foremost to allow you to start your vehicle. Do do this you need to to
be able to produce the high cranking amperage which is needed to turn
over your engine.
Accessories such as a fridge, on the other hand,
place different kinds of demands on battery resources - rather than a
short and very large discharge they draw a steady current over longer
periods of time, and if left unchecked will drain a battery completely.
Traditionally, these different requirements have
been served by two distinct type of battery - the first high cranking
amperage type is sensitive to discharges, and will very quickly fail if
subjected to more than two or three deep discharges.
Deep cycle batteries, on the other hand, cannot
produce the high amperage required to turn an engine, but are able to
service repeated deep discharges without affecting the battery's
performance.
You also need to choose either lead acid or gel
technology - the latter are maintenance free, and because they are
sealed they cannot leak.
In advanced modern batteries such as the Optima
the lead plates and separator are wound and tightly compressed into a
cell tube so they can't move, shed, or break, even in severe shock and
vibration applications which might damage flat plate batteries. These
batteries also offer the added advantage of higher cranking amperage and
the ability to withstand deep cycle use - although this benefit does
come at a cost
Mounting
Where you mount your batteries will depend upon
the model of vehicle you are using. Because of their weight, and the
fact that they may be full of acid, it is important to ensure that they
are well secured. If you have a Discovery you may well find that the
original battery mounts are unable to cope with the abuse that you will
subject them to off road, and once a battery is free to rock and roll it
will make short work of both itself and your battery tray.
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Charging
Where you are using two or more batteries you will need to consider how
these are to be charged.The simplest of systems will involve a manual
switch which allows you to switch the alternator current to an auxiliary
battery once the main battery is sufficiently charged. You will require an
expensive heavy duty switch capable of handling the amperage involved,
but it still depends on the driver remembering to turn the switch.
If you want something a little more user-friendly a split charge relay
joins the 2 batteries together for charging when the engine is running, and
separates them again when it's stopped.
Alternatively a blocking diode will allow both batteries to charge, but
will isolate the starting battery from discharges associated with the
auxiliary battery. There are disadvantages with this system too - the slight
voltage loss reduces your ability to charge your batteries.
An extreme alternative, depending on how much auxiliary equipment you
have, would be to fit a second alternator giving you two completely
independent electrical systems.
Inverter
An inverter steps 12 volts up to 220-240 volts, and will typically provide
you with 300W, which is sufficient to run small power tools. While not
essential, and inverter means that you can bring, and use in the bush,
equipment that relies on 220v-240v power, either directly or through
chargers. This includes useful power tools such as a drill and angle
grinder. Most modern inverters include automatic cut-outs that stop the unit
from draining your battery completely.
Accessories
Although a fridge is a luxury, it is definitely
money well spent, especially if you have any desert travel on your
itinerary. It's hard to put a price on a cold beer at the end of a hard days
driving, and the ability to carry fresh food can make all the difference to
your camp cooking. We can supply a range of low-current fridges, such as the
popular Waeceo Coolmatic CCF 35 litre fridge.
 Camp
life is also greatly improved if you have a good light source. Rather than
relying on high current bulbs, look for a 12v low energy bulb, which will
provide as much light, but draw a fraction of the current, and can fit into
an inspection light housing, which means you can use it under the bonnet, as
well as by the camp fire.
Another useful 12v accessory that we make ourselves
is our ceramic water filter/shower. This pump driven device allows you to
ensure that you are drinking clean water, and also allows you to have a
shower anywhere you stop.
In Southern Africa, where camp sites are well
equipped with such niceties as mains electricity, you will need an extension
cord which will allow you to run your fridge and other accessories without
draining you batteries
Solar Panels
If there is no external power available, and you expect to be stationery for
several days at a time, and especially if you still want to run a fridge or
other auxiliary equipment, it's worth considering a solar panel. Ideally you
should look for one that is capable of producing at least 10W, and you will
also need a charge controller to prevent battery drain during the night.
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