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Batteries......of the Lead
Acid Type.
Now a few snippets that
have enabled me to live with them in some degree of
harmony.
First rule: Remember the
wet stuff in them is strong sulphuric acid (electrolyte)
which varies from strong to very strong depending on the
state of charge of the battery.
It also has some
undesirable side effects, such as corroding most metals it
touches, eating holes in anything organic, and doing quick
and nasty damage to personal body parts.
Keep this in mind whenever
you handle a battery. If possible wear rubber gloves. Always
wear old clothes, and when carrying one put a whole
newspaper between you and it. Better still use a proper
carrying strap.
As well as containing acid
they also have in them lots of ergs (energy), and like the
electrolyte must be treated with utmost respect. To give
some idea how much respect, consider: When you press the
starter button on a 1952 Holden with its 6 volt system, the
first moment till the motor starts to turn over the battery
output is around 600amps which then drops back to 200amps
turning the motor. Compare this with 75 to 140 amps you use
to arc weld. Hence the 1/2 inch diameter cables to carry the
load.
“What has this got to
do with anything?” You may ask.
I venture to say, most
mechanics have a screwdriver or spanner with scars from
inadvertently shorting a battery!
When you work on the
starter side of things; there is no fuse to protect
you.
It is advisable to avoid
rings on fingers when groping under the bonnet. (They are OK
in ears, nose, and navel).
Metal watchbands are a
definite No-No...I have a friend who shorted his while
wrestling with his Morris Minor. Suddenly he had a stunning
roasted replica of an expanded band round his left wrist. It
even annealed the springs in the band.
Let’s face it.
Batteries aint what they used to be!
My father was, in the
1920s a battery mechanic with Willard Batteries, and later,
after WW2 a lead burner with A.G.Healings making
batteries.
In those days when
batteries were made with ‘Vulcanite’ cases, they
had a ‘sump’, which was a space underneath the
plates into which the lead paste settled as it fretted out
of the grids of the plates. There it accumulated out of
harm’s way until it reached the plates, shorted them
and the battery died. This process took 5 to 10 years in a
well cared for car battery. and nearly twice that for
stationary ones in lighting plants. These days you pay extra
for a battery that may last 3 years.
Why is this so? In order
to sell more batteries, and to make way for all the other
technicalogical junk under the bonnet!
The straps and sometimes
even the posts were removed, and most importantly the sump
was dispensed with. This makes the battery smaller with
about the same capacity. As soon as there is any
accumulation of sediment in the bottom the battery
‘karks it’. Moral: The deeper the case, the longer
you can expect the battery to last.
There are still places
that rebuild batteries, so if you have an old deep case.
That’s the way to go.
There are two main enemies
of lead acid batteries.
First is being left
discharged.
This causes the lead paste
to turn to lead sulphate which is electrically bad news and
dramatically shortens its life. Moral: Keep it well
charged.
If in doubt put it on a
trickle charge (about 1amp) for a day or two.
Some people have a
‘thing’ about always taking the filler plugs out
of a battery whenever it is put on charge. I am quite
prepared and willing to be corrected on this piont. But! If
a generator can pump 10 or more Amps, and an alternator 40
odd Amps, into a battery under the bonnet. Why doesn’t
it explode there?? I certainly don’t have any problems
with my 2.5 sometimes Amps charger.
Second is contamination of
the electrolyte.
Be very careful what you
put in it. When you peer into the holes on the top there
should always be enough acid to cover the plates by about
3/8 of an inch. There is usually some sort of indicator
built into the filler plug hole. If you over fill a cell
(there’s one for each filler hole), when the battery is
fully charged it may overflow. (Reread what happens when
acid gets on things). Plus the electrolyte becomes
diluted.
Electrolyte is lost three
ways.
Being spilt: How, when,
and why!?
Evaporation: Which takes a
very long time, or too hot location.
Gassing: Caused by a high
rate of charging, and or, normal use.
Disregarding the first
two. Gassing is evident if you look in the filler hole when
the battery is on a charger, or the engine is running, or
even immediately after charging has stopped. There will be
bubbles rising from the plates.
A word of caution here.
Those bubbles are produced by electric current breaking down
the water in the electrolyte to hydrogen and oxygen. In
water (H2O) these two are OK, but when separated as gasses
and mixed they are explosive.
(A digression here!) At
Willard Batteries they used to cycle (charge and discharge)
the batteries about 50 at a time. The current came from live
bus bars along the bench. The rule was to switch off the
current when connecting or disconnecting a battery. Needless
to say there was plenty of hydrogen being generated. Every
so often someone (my Dad included) flouted the rule and the
spark created would explode one or a string of batteries.
Dad did it once too often. Having his head held under a cold
tap for 20 minutes was hard to forget! Only his glasses
saved his sight.
The charging rate on an
Austin-7 (8amps) is regulated by the third brush in the
generator and does more to protect the generator than the
battery. In your ‘modern’ the voltage regulator is
adjustable and looks after things.
If gassing is too vigorous
the bubbles will dislodge the lead paste and shorten the
battery life. If there it any sign of the battery warming
itself, this indicates overcharging.
Back to what to put in the
battery to maintain the electrolyte level. This
shouldn’t need doing more than once or twice a
year.
Never! and I stress Never!
put tap water in a battery!!!
It is full of metallic
salts, iron, zinc, aluminium, and others. Some of which
might be good for you but poison to a battery. Unfortunately
even rain water is suspect these days.
From time to time products
appear on the market claimed to increase battery
performance/life. My late friend who was a chemist with
CSIRO spent 2 years on battery research and tested these
products. The result was always the same, none
worked.
When the electrolyte needs
topping up the only thing to use is distilled water. As pure
as you can get, anything else will upset the chemistry of
the battery and destroy it.
You can buy distilled
water at the garage for about $3 per litre, or make it
yourself. as follows.
Take a shallow glass dish
and put an inch of tap or rain water in it. Place in the
frig or freezer.
When 1/4 to 3/8 inch of
ice has formed on top, remove the dish and poke a hole
through the ice at one edge and carefully drain away the
water and any sediment underneath. Melt the ice. This is
‘freeze distillation’, or ‘zone
refining’. If you are keen you can repeat the process
using the melted ice water to make it double
distilled.
Explanation: As water
freezes pure water turns to ice first and floats to the top
concentrating the impurities in the unfrozen water beneath.
The main thing is to avoid contact of the purified water
with any metal.
A Hydrometer is an
excellent investment($5 to $6).This is the only device to
tell exactly the state of charge of a battery. It look like
a turkey basting syringe with a coloured glass float inside.
What you do is gently and carefully suck the electrolyte up
into it until the float inside floats. The level of the acid
on the float calibration indicates the density (Specific
Gravity) of the acid which is directly related to the amount
of charge in the battery. If the reading is low put the
battery on charge. If it is very high check the level of the
acid in the battery and view the charging rate with deep
suspicion.
The electrolyte should be
water clear in the hydrometer. If it is cloudy you have
problems. Even if it is still functioning the battery may
not be trustworthy... Another indicator a battery is unwell
is variation of SG from one cell to another. Don’t
transfer any acid from one cell to another.
When you finish using the
hydrometer wash and flush it thoroughly or it will eat holes
in everything it touches.
If and when enough
electrolyte or its vapour seeps out of your battery and
white chalky growth appears on nearby steel parts (green if
they are brass), gently pour very hot tap water on them and
it should disappear like magic, even quicker if you lace the
water with bicarb soda. BUT! be careful not to allow any of
it to get into the vent holes in the filler
plugs.
If like me, you remember
the rubber gloves afterwards instead of before, be sure to
wash your hands very thoroughly with plenty of toilet soap.
You will know straight away that, not if, you have acid in
them, because the soap won’t lather properly. If you
have the slightest trace of acid, if it doesn’t make a
hole, certainly will bleach any clothing you touch. (Been
there, done that!).
Peter Booth
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