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
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.
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.
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.
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 your batteries.
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.