Techtip14

SAVVA - TECHNICAL TIP NO. 14

Batteries

One often hears the complaint – “batteries ain’t what they used to be” - absolutely true,
but it’s not because modern batteries are poorer in quality, but because modern cars have a
totally different requirement to earlier cars.
The problems we have with our older cars is that they are not used regularly enough and the
batteries are usually flat or half flat, resulting in under-voltage and shortened life –
usually 12 to 36 months.

As a comparison to new and older car usage, lets look at a modern car’s requirement –
firstly, and perhaps most importantly, they are in daily use. They have starter motors
that can swing high compression engines at an alarming rate. Add to that, electric windows,
air conditioning, computers, quartz and halogen lights, plus numerous other electronic this
and thats. Once the engine has started, the alternator and its electronic regulator takes over,
producing lots of constant voltage and current to accommodate the car’s electricity needs.
There is a massive draw from the battery while starting, but the modern alternator puts this
back by pumping around 50 amps (and over) at a time, even at just above idle speeds. Under
these conditions, it’s not unusual for a modern battery that’s in everyday use to last well over 6 or 7 years.

Older cars by comparison, once started, only require a couple of amps (for the coil) to keep them
mobile and perhaps five amps to re-charge the battery. Even if the lights are on they probably
require no more than a total of 15 or 20 amps - which is invariably about the entire old generator
can handle. The voltage and current regulation on generators are speed dependent, which means the generator
is only effective at higher engine revolutions - the battery is charged up again, but very slowly.

So what are we saying? Well, basically that modern batteries are excellent for the purpose
they are made for – BUT, they are not designed to stand around unused. If they stand discharged
for any length of time, they won’t recharge to their original voltage – they will die a slow death.

We, the car owners are mostly to blame for this tragic comedy – why?

·    We don’t check water levels on a regular basis.
·    We don’t charge the battery regularly with a charger.
·    We don’t use a hygrometer to check the specific gravity.
·    We don’t use our cars often enough to charge the batteries.

There are two other suggested solutions;

1.    There are batteries that will give around ten years’ life and don’t go flat when standing -
these are Gel batteries. Expensive yes, but worth every cent. We’ll discuss the availability etc in the future.

2.    An alternative is to purchase a "Hawkins SMART Battery Charger" or similar, that will
keep the battery fully charged at all times. It is a readily available device that is made for
keeping boat and caravan batteries fully charged when not in use. It is not a conventional
battery charger and will not however recharge a battery that has run down, but will keep it fully
maintained for as long as it is connected. One unit can be used to serve two vehicles by changing
over every few days. They are available in 6 or 12 volt and cost in the order of R400, but you then
know the car will always have a fully charged battery.

Eric McQuillian