“MY BATTERIES ARE ALWAYS RUNNING DOWN!!"

The above complaint is a common refrain from person going camping, or On Safari, for more than a couple of days.
Most campers and 4x4 users employ appliances that make life more comfortable whilst ‘in the bush’. These can include:

• Fridges
• Freezers
• Lights
• Microwaves
• TV & DSTV
• Hi Fi systems
• Pressure pumps for showers
• 2 plate stoves
• Rotating Braais
• Small compressors

Often auxiliary batteries may number from 1-4, weight, space and recharging of these batteries is always a major consideration.
Another major consideration is to make your appliances as energy-efficient as possible, as this will prevent discharging your batteries too quickly. Energy-efficient appliances can use up to a quarter of the power of standard appliances.

EXAMPLE 1

If we look at this example of consuming 100 amp.Hour per day at 12 V DC, then it stands to reason that we will need to replenish this and this can be done in 7 different ways:

• Alternator stator upgrade
• Alternator upgrade
• 1 (or more)  solar panels
• A 220v charger working from a small genset
• Booster alternator regulator
• A 220v charger working from Eskom Mains.
• A small wind generator

SPARE ALTERNATOR POWER:

Your vehicle’s alternator is optimised for recharging or maintaining a high cranking battery (The battery that is used to start and operate your vehicle) – so the charging voltage might not be ideal for recharging of a deep cycle battery
Let us assume, for the purposes of this exercise, that you have a 75 amp alternator which has 25 amps of spare capacity when it isn’t raining, without aircon on, etc.  If we divide this power between the 2 auxiliary batteries, we end up with 12.5 amps of available charging.  Each battery is being discharged by 50 Amp.Hour per day, so it would take 4 hours of charging to bring the batteries back to their original levels!!!  Our options to improve on this scenario are quite promising, however.

Firstly:

This can increase your output from 15-30% depending upon the make and type of alternator. You also have the option of installing a more powerful alternator which can increase your output by more than 50%.  If you have room for a second alternator (rare, but possible for those vehicles with no A.C) then the possibilities are even greater (bear in mind fuel consumption will also go up!).

Secondly:

• Increase the charging voltage ON the battery itself. It would monitor the battery voltage of that specific  battery,  as well as ensuring that a proper charge reaches that battery
• Increase the alternator output charging voltage, which is critically required for the ability of your battery to ABSORB the charge.  Increased alternator current means nothing - if the battery is not able to absorb the charge- It’s like trying to Dump  400 Litres of petrol in a 100Liter tank....it just cannot accept it.
• The MXS, increases LOW RPM charging (this is RPM while driving around slowly) by up to 40% . Does this mean your 60A alternator now ‘magically’ charges at 90A? No, it doesn’t, because at low RMP, it was probably charging 20A and this is now increased to 30-35A  which makes quite a difference in total power absorbed during periods of driving slowly.
• These 2 additions should be essential for any one pulling more than 75 amps per day from their auxiliary batteries.

Thirdly:

SOLAR PANEL: A solar panel has some advantages:

• Clean power
• Charges even when you are stationary
• Quite a cheap method - if there is no grid power available
• No noise factor
• No extra fuel consumption

But it also has some disadvantages:

• Can be Bulky
• Needs to point at the SUN at the correct angle
• Susceptible to dust and dirt - affecting efficiency
• Doesn’t work on rainy or cloudy days
• Only generates around 4.5 amps from an 80W panel
• Only charges between 4.5 to 5.5 hours a day, depending upon your location in S.A.

So, if you are drawing only around 25-30 Amp.Hours per day, a solar panel is an option, especially if you have some ‘travel time’ with your vehicle everyday to help ‘top up’ any shortfall by using the vehicle’s alternator.

FOURTHLY:

SMALL GENSET: This is an option employed by some people, but again, with its Pro & Cons:
ADVANTAGES:

• Power available at any time
• Can  power up motors and pumps more efficiently
• No need to Invert power
• Reduces need for batteries
• Can also be used for charging up batteries

DISADVANTAGES:

• Extra weight to cart around
• Takes up a fair amount of space
• Needs 2 guys to off and on - load
• Noisy (banned in certain areas)
• Exhaust fumes
• Can frequently give trouble
• Requires extra fuel
• Expensive to operate

As a rule, most ‘Bush’ people do not like to transport Gensets around with them.

FINALLY:

GRID POWER:
This is always the cheapest and easiest solution - if you have access to it.  Charging up your batteries at night whilst connected to the grid is obviously ideal, but many people are nowhere near a grid point, when truly ‘in the bush’.
WIND GENERATOR:
Sounds quaint, but not very practical when bashing through the bush - as they are often mounted on roofs for optimising access to wind.  More commonly used on boats, where they are far more practical.  Like solar, they are quiet, but unlike solar, they can work 24 hours a day and through all types of weather!

EXAMPLE 2:

SOME IMPORTANT POINTS FOR 4X4 POWER INSTALLATIONS:

• Ensure that you wiring thickness is up to the task requested of it.
• Ensure that your connections are of good quality – check regularly
• Avoid using domestic appliances not designed for portable travel
• Use energy-efficient appliances wherever possible (good choices now)
• Top up your fridges and batteries prior to departure
• Bring your Mains charger with you – just in case
• Watch out for new developments that become available (PMP have several for 2010!)
• Keep a check on your batteries to gauge the performance of your system