| Most of us throw a cheap battery in the 4WD, zip around for a couple of years, then begrudgingly replace it with the first one available when the old lead-box goes into arrest and flat-lines one cold morning.
For the majority of 4WD enthusiasts this is probably quite a satisfactory approach to your vehicle’s power supply; quite frankly if you don’t need a fancy power supply – don’t put one in! Save your money for the pub, that’s my vote.
One could be forgiven, whilst at said pub, for thinking that the battery in your vehicle really is just a rectangular box, full of lead, bloody heavy, and the only difference between batteries is the label on the front.
Well, to an extent this can be true, some batteries are mass-produced and the only real differences are price and yes, the label on the front, but truth-be-known the battery in your vehicle is anything but a rectangular box. Any auto-sparkie will tell you there is a lot more to it, and the electrical system that supports it, than meets the eye.
At the end of the day, like most things what really matters is what you actually do with the power supply in your vehicle. It is this, which primarily determines how long you can get away with a cheap battery in your vehicle. If you push your battery, and work it hard, then it too will flat-line on you one day and probably a lot sooner than one might think.
Most of what is discussed below will be in the context of remote travel, because it is in this environment that you would probably take your vehicle’s electrical power system a lot more seriously than any other. Simple things can go wrong quickly and without support this can be problematic in remote country. Your HF radio needs power to call for help.
Once upon a time, a certain 4WD was loaned to a friend. Understandably, the lights were accidentally left on all day, and not surprisingly the vehicle would not blink an eye 8 hours later. No big deal, happens all the time, we all do it, LOL as the say on the internet.
Unbeknown to the driver, the vehicle had a dual battery system and could very easily have been started with the flick of a switch, but the local WA authorities were called in none-the-less, and it was decided to jump-start the vehicle. This occurred without mishap.
Well, that was until plumes of black smoke started rising from under the engine bay, the sides of the bonnet, from under the wheel arches, and shortly thereafter the driver’s ears. Sadly, the engine wasn’t killed for another 5 minutes as the mechanic scratched his head (!!) - but when it was, the damage had been done. Later that evening, I was welcomed in the driveway by a gentleman who tilted his tray and rolled the vehicle off before sheepishly departing company. My mate was pretty upset, he didn’t know what happened and felt responsible.
Unfortunately there was no explanation from the tilt-tray driver as to what happened apart from “your vehicle has a problem, sorry mate, good luck with that. Oh, and I wouldn’t drive it if I were you”.
Whilst I can’t say I was overly impressed with the professionalism of this particular organisation, accidents do happen, and sometimes it’s a case of “dry your eyes princess” isn’t it. This time, however, I was seriously concerned as we were due to leave for very remote sections of Central Australia in just a few days. It bothered me that my seemingly trusty vehicle could have a simple jump-start and suddenly be rendered “un-drivable”, not to mention the risk of fire. These are non-compatible risks with remote travel and warranted a cancellation of the trip until a post-mortem was performed. In reality, all we knew was that the vehicle “blew up” and the cause was completely unknown.
The post-mortem turned out to be very extensive and in the end cost near on $2000 to get the vehicle back to a reliable state with a suite of new components. Actually, the alternator primarily generated the heat, but the wiring looms and at least one of the batteries were smoked out and simply weren’t reliable anymore. Certainly not for remote country – that’s for sure.
This scenario demonstrates just how quick and easy it can be to have a serious problem with your battery system if you don’t know what you are on about in remote country. In town, no big deal; out bush it’s far from amusing. A lot of people scratched their heads as to the cause of this problem. Everything from the diodes to the battery were blamed.
What went wrong? Quite simple in the end; the main battery was dead-flat after leaving the lights on. The vehicle woke up to the problem and automatically isolated the 2nd battery as a safety precaution. When it was jump-started, this dead-flat battery had a very high resistance (whereas the 2nd charged battery had low resistance) and being such high-capacity was ready and willing to take every electron as quick as the alternator was willing to hand it over. This generated a huge amount of current to be transferred to the flat battery when the engine was revved right up for only 10 minutes. Current is the rate at which electrons are being delivered, think of it as how fast the power is ‘flowing’, and current is quantified in Amps. Bear in mind that whilst the alternator was ‘rated’ at 110 Amps, this particular one was not current limited, but only voltage limited. This means that the voltage in any alternator should be regulated to protect your vehicle’s electronics, but the current may be proportional to the rmp of the engine and therefore alternator (NB there are exceptions to what I am saying here). We later bench-tested an identical alternator delivering about 140 Amps at the same engine rpm.
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The long and short of it is, jump-starting is very common, and rarely goes wrong when procedures are followed correctly. This was a particularly unlucky case, but illustrates the point well. Fundamentally, it could have been avoided by limiting the amount of current being delivered to the battery. How do you do this?
1) Never rev the engine initially on a dead-flat battery. A flat battery wants to suck all the current it can; so take it slow. As the battery accepts charge its resistance will lower and it is safer to rev the engine as the current required to develop useable charge will also lower.
2) To help limit some of the current it is advised to put the headlights, even spotlights on and draw some of the power away from the offending battery.
3) The best thing to do if you have the opportunity is to trickle-charge the battery at home.
This topic can go on and on and on, but to cut to the chase, if you are heading into remote country here are a few tips worth considering when setting up your battery system:
1) Get yourself a dual battery system installed, for a number of reasons. Experienced installers will know to set it up properly.
2) Choose your batteries carefully, if you want to rely on them, and can afford it, spend the extra money and get top quality. Cheap batteries use impure recycled lead, which leads to poor performance.
3) Remember that the purity of the copper in your cables can also affect performance. High-grade cables can make a lot of difference in certain circumstances.
4) Consider a dual battery monitor, so you can actually see what’s going on whilst inside your vehicle. There are some great systems available and this can allow you to monitor alternator performance, each battery separately and identify how your power is being managed.
5) Consider a good quality dual battery isolator, if not already installed. The newer automatic ones are great little devices and are virtually ‘set and forget’. They manage battery charge and protect from accidentally discharging both batteries – an absolute must for remote travel.
6) Consider how you will use your batteries peripherally. For example, if you are running a fridge, you want to avoid deep cycling all the time if at all possible. If you must deep cycle then probably not a good idea to do it on a cranking battery. Are you running a winch? How much power do you anticipate it might require?
7) Think seriously about sealed gel batteries. Read up on their specs, the good ones are absolutely fantastic in performance. Amongst other things, sealed batteries keep the red dust out, and most accept and deliver charge much better than their counterparts.
Setting up a good power system in your vehicle is surprisingly important when you start going bush and especially when you begin adding accessories. It really is worth doing your homework and seeking some expert advice if you want some good results. The whole topic is mind-blowingly complex when you get right down to the nitty-gritty. Sometimes (if possible) it is better to go for the quality in the first instance rather than having to replace equipment and put up with poor performance along the way, and usually it pays to get some advice from the experts.
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