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A WITNESS Wheels reader asks: “What causes a battery
to explode? And are older Camry models particularly prone to such a shock to the
system, as some say?”
There are two reasons why a battery could explode — the alternator
either over charged the battery or a battery cell had a fault that led to the
highly combustible gasses, which are made during charging, to explode.
We asked Mr Battery in Pietermaritzburg,
where the technical team said they had never heard of any Camry model suffering
from over-charging alternators, a problem which they did sometimes see in
nineties’ Isuzu KB bakkies, and then it is not the entire alternator, but the
voltage regulator that packs in.
Mr Battery’s technical team said the likely cause of the Camry’s
battery exploding was a faulty cell, which would lead to fluid in the cell to
start boiling and rapidly emitting acid and boiling water.
Battery acid can burn clothes and skin off the flesh, which is way
it is important to wear safety goggles and protective gear when working on
batteries.
The pressure causes the side of the battery to buckle, which is
does with a loud crack and damage to the wiring in the path of the escaping
fluid and gas.
While modern batteries are built to be very robust, they can suffer
interior damage when a connection shakes lose.
Sealed batteries do not allow hydrogen and oxygen that forms during
charging to escape, but collects the gasses under the cap where it to recombine
as water. This prevents having to top up sealed batteries, but if a sealed
battery has been damaged on, for example a 4x4 excursion, and then gets
trickle-charged overnight as often happens in outdoor situations, the arch
inside will explode both combustible gasses.
In the case of unsealed batteries that are not regularly topped up,
hydrogen and oxygen gas can collect above the empty cells and can ignite when
the starter draws a heavy charge from the battery.
What most often happens, however, is that oily debris seal the
small gas escape vents on top of an unsealed batteries, keeping the gas inside,
which then ignites when a spark between the lead plates occurs.
Because of the gasses escaping from the vents, it is never a good
idea to smoke while working over an unsealed battery.
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| The fate of car with a faulty battery cell. |
• Be safe when jump
starting a dead battery:
Because a discharged
battery has a lot of hydrogen gas, do not cause a spark or smoke cigarettes near
a dead battery. Wear safety goggles to inspect both batteries for cracks, leaks
and damage. If any of these exist, do not use the battery.
• How to hook up:
Link the red jumper cables to the positive terminals first,
starting with the dead battery.
Secondly, hook the black cable to life battery’s negative pole and
the other end to a solid metal away from the dead battery. Do not hook the up
the dead battery’s negative terminal, as this can cause a spark, but clamp it as
far away from the battery as the black cable allows.
Remove the cables in reverse order.
