Campfire Mythology - Caravan and Motorhome Books

The great enemy of the truth is very often not the lie – deliberate, contrived and dishonest –
but the myth – persistent, persuasive and unrealistic."
That was John F. Kennedy’s commencement address to Yale University back in June 1962.

It sums up one of the biggest difficulties faced by technical writers in many areas.

As Ample Power Co, in the USA, point out: "the problem is not so much what people don’t know, but what they think they know that simply isn’t true." Thus before the hapless writer can explain how something really works, or what can realistically be expected, he or she has to contend with often long-held but totally incorrect beliefs. And not a few people (and vendors) who believe they are immune to the more basic laws of physics. My column this month is a compilation of the most tenacious such myths.

This is a superb example of people believing right things for totally wrong reasons!

It is absolutely true that, in some circumstances, feeding a battery with aspirin will partially revive it. So will Panadol, the Mozart Horn Concerto, Reiki, (the ‘laying on of hands’) for half an hour - that one’s even in some Reiki handbooks. So does reciting Elliot’s ‘The Wastelands’ – or swearing profusely at it for half an hour. Any or all of the above will help – Reiki works best of all, but swearing comes close.

It’s simply because a starter battery that has not quite started a motor still has some energy left in its electrolyte. After 30 minutes or so that energy will be available for use. Thus anything, anything that enables it to rest for half an hour will work.

It’s not the aspirin that works – it’s the time it takes to find it. Many Mozart concerti run for half an hour. So may a Reiki session.

Reiki works best because laying hands on the thing warms it up – and that speeds the battery’s internal electro-chemical reaction. But channelling energy? Sure, but it’s just thermal.

2. A car battery must not be placed on concrete or even a bare metal carrier(the latter myth was actually revived in a recent 4WD magazine)

It was true way back when batteries had leaky wooden cases. It was also true of the very first hard-rubber cases. With those, concrete or metal could form a conductive path. But it has been untrue of vehicle batteries since the 1950s.

Leakage can however occur if conductive deposits form on the top of batteries and bridge the terminals. Clean them using a tablespoon of bicarbonate of soda, (i.e., baking soda - ask the cook) in half a bucket of warm water.

The opposite is true! Deep-cycle battery heaven is being put on the optimum float charge and otherwise left alone! Any draw, no matter how slight, shortens a leadacid battery’s ‘life’.

As few people keep batteries as pets, their optimum economic life span is obtained when they are used from 100% charged down to 80% charged. A more practical life span is to use them down to 50% charged.

A speaker at a recent CMCA Rally seminar – not me, allegedly retold this one! Short of running over it with one of the heavier Winneswagmobiles it’s the quickest way to kill a deep-cycle battery. Here, people confuse deep-cycle batteries with Ni-Cad batteries (of which it is true).

Many caravan and motorhome builders hold this incorrect and potentially dangerous belief. It dramatically illustrates the urgent need for industry standards over and above ‘following what my grandfather thought was right’. Every battery maker on earth stresses that rechargeable batteries must be ventilated to atmosphere. Sealed or otherwise.

Vendors telling you this are going against battery makers’ explicit advice. I quote Hawker Energy’s Ronald Hamel (the inventor of AGM batteries): "A sealed battery must never be operated in a gas-tight container". (Several CMCA Members have told me that one motorhome vendor still insists it is safe - even when confronted by written advice to the contrary from the very battery maker this vendor uses.)

Not so. This is again a case of mistaken identity: it was true of early Ni-Cad batteries, but never of lead-acid batteries.

7. If I mount a small windmill or turbine on the roof of my bus I can charge batteries for free.

Sure – and connect those batteries to an electric motor driving the rear wheels and drive along for nothing! There are various versions of this one. They are all based on a belief that there is free energy out there if only it can be tapped. But, as Malcolm Frazer once put it: ‘there’s no such thing as a free lunch". If you put a windmill on the roof of the bus (and it always is a bus!) it will create extra drag. This will cause the bus to use more fuel: far more than were it generating the same electrical energy by running an alternator – because an alternator set up is more efficient than a windmill.

8. When battery voltage drops, anything that battery runs draws more current to compensate

This surprisingly common belief is due to a misunderstanding of wattage. Its basis is that since one watt is one amp times one volt, a 12-watt globe that thus draws 1 amp at 12 volts must therefore draw 1.09 amps at 11 volts. Not so, that globe is rated at a specific voltage (eg., 12). At 11 volts it is an extremely light inefficient 11- watt globe.

9. When driving over rough stuff, you need more air in the tyres to withstand the shocks

Again, the opposite is true. Increasing tyre pressure increases the local stresses when, for example, running over a rock. If done, that tyre is likely to suffer casing damage, or may even burst. Lowering pressure (by about 30%) enables the tyre to fold around rocks and stuff without damage.

It’s mainly tourists running their tyres at high pressures who have tyre problems up in the Kimberley (where we live). But this myth is not wholly bad. It boosts the local economy every tourist season.

10. If I’m short of fuel I drive faster because the engine is not running for so long

This myth too is far from uncommon: I encountered it again only a few weeks back with a man towing a big caravan behind an equally big 4WD. He told me he had not realised the distances between fill-ups from Port Hedland to Broome and said he had to drive at 120 km/hr – ‘because I run out of fuel every three and a half hours’. Once over 70-80 km/hr the fuel consumed by a vehicle is proportionate to the square of the speed. If seriously low on fuel, increase tyre pressures (if possible) to the tyres’ maximum safe level – and drive at 50-60 km/hr maximum.

11. Door-opening fridges are not nearly as efficient as top opening fridges because all the ‘cold’ falls out when the door is opened

This is reaching a generally correct conclusion from a mostly incorrect assumption.

Cold air does tumble out when the door is opened, but the energy to heat or cool that mass of air is negligible. The reason for the generally lower efficiency is more likely to be thinner insulation, and leaking door seals.

So does telling them you hate the very sight and smell of their terminally ugly mothers…the reason it works is that when you tell them anything you breathe carbon dioxide over them. And that’s what they live on – of course they grow! But I accept that here, truth lacks a certain romance.