Millions intended to be spent on the health needs of Eastern Cape residents have gone missing from d.
I HAVE noticed for some time that battery manufacturers have been making it difficult for vehicle owners to open the vent caps on maintenance-free car batteries. First they covered the caps with a strip of adhesive tape, and now, on some of the latest batteries, the vent caps have a design that makes it impossible to remove them without damaging them in the process. I can understand battery manufacturers telling owners they don't have to open the caps because it's unnecessary to check the acid level on maintenance-free batteries, but why do they go to such lengths to ensure that customers can never open the caps?
What harm can it do to a battery if I occasionally have a look at the acid level? And what exactly goes into the so-called silver calcium batteries?
I PUT the question about the vent caps to somebody in the technical department of one of the big battery manufacturers.
His answer was simple: they have found that people will insist on opening the vent caps if it is at all possible.
That in itself can do no harm, but what happens thereafter is the problem. Having opened the caps owners seem to have a strong urge to top up the cells.
Unfortunately this very often leads to cells that are overfilled, and when the engine compartment gets hot, thermal expansion pushes some battery acid out of the overflow tube . on to bodywork or engine components where it eats away paint and aluminium alloy.
Angry letters and claims for damages are then received from owners who strenuously deny having ever added battery water.
A second and related problem is that the topping up is often done in garage forecourts or during services, without the knowledge of the owner, and with little control over what kind of water is used.
It might be tap water, borehole water, water from contaminated containers - things that are unhealthy for a battery. Predictably, the battery then expires prematurely and claims ensue from owners who swear they have never put anything but pure distilled water into the battery.
The message from all this is clear: Leave the vent caps on a maintenance-free battery alone, at least during the warranty period. In fact, it seems best to leave them alone for the life of the battery.
The silver calcium story is the latest chapter in the ongoing history of the lead-acid battery, which was invented more than 150 years ago and has been a stalwart of the motor industry since about 1915.
It was found that by doping the plates with small quantities of calcium, you can cut down the water loss from the cells by a massive 90percent.
The calcium has the effect of raising the voltage at which the battery starts to "gas" (give off bubbles of oxygen and hydrogen gas during charging).
It is when a battery is gassing that it loses water. The calcium also lowers the self-discharge rate when the battery is not in use, thus giving a far longer shelf life than older batteries had.
A small quantity of silver, added to the positive plates, inhibits corrosion of the plates, especially at higher temperatures, and this extends the life of the battery.
Though a maintenance-free battery should never need topping up, you can ensure that you get its full service life out of it by keeping an eye on the following:
l The alternator charging voltage. For a lead calcium battery it should not exceed 14,8V (for the older type of battery it was 14,2V), otherwise gassing, and consequently water loss, will occur.
The condition of the terminal clamps. If there is any sign of corrosion or whitish deposits around the clamps, remove them, clean with a strong solution of bicarbonate of soda, use fine sandpaper to get the mating faces of the clamps and terminals smooth and bright, then fasten the clamps securely. Finish by spraying the terminals and clamps with a wax-based anti-corrosion coating.
l The security of the hold-down cradle. Although the latest generation of batteries are claimed to have a stronger, more rigid internal construction, vibration remains a killer of batteries.