Battery Fundamentals

BATTERY FUNDAMENTALS
Early Rechargeable Battery

Invented by Gaston Planté in 1859, the
lead-acid battery was revolutionary
because it could be recharged instead of
discarded. The chemical reactions that
produce current gradually cause a battery
to “die” by converting the sulfuric acid
into water and lead sulfate. However, in a
storage cell the chemical reaction can be
reversed by running electrons through the
battery in the direction opposite the
discharge process. This recharges the
battery for further use.
AVAILABLE ELECTRIC POWER
A large saving box can deposit correspondingly large amount of money.
Conversely speaking. A large amount of money can buy many things, or last
long. This is also true of the battery. Larger the battery, greater power can be
deposited. Well, then, how can the capacity of the battery be expressed?
Mechanic Development ADVANCE ELECTRIC 1

If a uniform current is continuously

discharged from the fully charged
battery, the voltage o£ the battery
gradually goes down as shown in the
graph below. It suddenly falls down
sharply when the voltage exceeds a
certain level. If battery discharging is
allowed to continue, the battery
suffers. Therefore, it is necessary to stop discharging before the battery is
damaged. The voltage at this time is called the "final terminal voltage".
The capacity of a battery, then, is expressed in terms of ampere-hour (Ah),
which can be found by multiplying the ampere (A) by discharging period (h).
This is called the "battery capacity".
Battery capacity with the intensity of current selected to last a period of 20
hours of discharging time is called the "20-hour discharge rate capacity". The
unit of Ah is often used to explain this capacity.
As the final terminal voltage when measuring 20-hour discharge rate

capacity is specified to 1.75V per battery cell, final terminal voltage will be
10.5V if the battery is rated for 12V, while final terminal voltage will be
5.25V if the battery is rated for 6V.
Therefore, a 12V battery with 200 Ah, if it is fully in charge, can last 20
hours of continuous use without causing voltage drop below 10.5V when three
pieces of 12V, 40W electrical bulbs (10A current flows) are applied as a load.
Furthermore, 20-hour discharge rate capacity of battery is based on the

electrolyte temperature of 25°C (77°F) unless otherwise specified. Therefore,
if the temperature o£ electrolyte is different, the capacity can also vary. Since
the capacity will fall if electrolyte temperature is low, the battery will be
damaged if it is used in winter just as in summer. Refer to the subsequent page
for a detailed description.

WHEN WEATHER IS COLD, ELECTRIC POWER CAN NOT BE

GENERATED AS EXPECTED
You may not feel like going out in extremely cold weather. If you go out
in such a weather, it is possible that you have a strain in your shoulder or
leg.
The battery, too, does not develop much current in an extremely cold day.
Using a battery in such a time may damage the battery.
Battery capacity decreases when the temperature of the electrolyte falls. In
such a case, a period of time before the output voltage goes down to final
discharge voltage will be shortened unless otherwise discharging current is
reduced.
If you do not want to have shortened discharging time, it will be necessary
to reduce discharging current. To find how much 20-hour discharge rate
capacity will be reduced when the temperature of the electrolyte changes,
refer to the graph below.
The beside graph is plotted with the

capacity as 100% at 25°C (77°F).
Capacity change at varying
temperatures is also given in it. As
can be appreciated
from the graph, at -20°C (-4°F), the
capacity will be about half as much as
that at 25°C (77°F).
The battery will be have far reduce capacity when the temperature of the
electrolyte goes down too low. In winter, therefore, do not use too much
discharge current without battery re-charging, or the voltage will fall below
the final terminal voltage and battery will be damage.

RUN FASTER, QUICK COMES FATIGUE
Referring to the above graph, you will see that the available capacity of
the battery for one hour discharge rate is reduced to less than 70% of that
capacity for 20-hour discharge rate capacity. If discharge rate is small, the
final terminal voltage will be lowered.
As described, if the battery is discharged at a large current rate, its
available capacity becomes small.
Consequently, when using current of the order of several hundreds

ampere to the starting motor, the battery can be used only at an extremely
small capacity. If this is done in winter, the capacity will be further reduced,
making it necessary to use the battery at a still lower capacity in that
instance.
For example, a 200Ah (20-hour discharge rate capacity at 25°C) battery
can be used only at scores of the Ali capacity in that case. Japan Industrial
Standards (JIS) state that in a test (a high rate discharging test), in which
500A current is discharged from the 12V, 200Ah battery at -15°C (5°F), the
time to last until the battery voltage falls to the final terminal voltage level
is more than 4.8 minutes. Thus, if this is converted into the capacity, it will
be given by the formula 500A x (4.8160) h or more = 40 Ah or more
This is a very low capacity, indeed.

ELECTROLYTE
When climing a mountain, you can recover from fatigue if you take a rest.
However, you will not have the original stamina in yourself even if you can
recover from fatigue. So you will get tired before long.

The same thing is true of the battery. Battery voltage can recover to almost
the original voltage level if discharging is discontinued for some time when
the voltage went down due to discharging.
However, this does not mean that the lost or consumed power can be
recovered when the voltage recovers.
It is impossible to know from only the voltage measurement just how
much electrical battery power has been consumed. As has been described
previously, however, since the specific gravity of electrolyte goes further
down if power is consumed more and more, you can find just how much
current has been discharged by measuring it with use of a hydrometer. Note
the following graph.
In this graph, discharge ratio is set at zero when battery is fully charged
and set at 100% when the battery has completely been run down.

Referring to the graph, if the specific gravity of the electrolyte is 1.260

when the battery is fully charged, it will be 1.160 at 50% discharge ratio (as
read on the actual line.) Also, the specific gravity will become 1.060 when
the current is fully discharged. If the specific gravity of the electrolyte is
1.280 when the battery is fully charged, now observe the dotted line.
Incidentally, the Japan Industrial standards specify that the specific gravity
when the battery is fully charged is 1.28 in cold regions, 1.26 in temperate
regions, or 1.24 for tropical regions.
At any rate, to avoid damaging the battery due to too much discharging, it
is advisable to recharge it when the specific gravity of the electrolyte has
fallen to 1.20.
The specific gravity of the electrolyte abovementioned is based on the
ambient temperature of 20°C (68°F). It is necessary to know the amount of
discharge by converting the specific gravity on the basis of 20°C if any
specific gravity is obtained at temperatures above or below 20°C.

The specific gravity of the electrolyte increases in proportion to a drop in

temperature, and it can vary 0.007 at every 1°C. Therefore, the specific
gravity of the electrolyte 1.214 at 0°C (32°F) can be converted to that at
20°C (68°F) by the following formula:
1.214 - 0.0007 x 20 = 1.200 at 200C (68°F).
The electrolyte is rendered easier to

freeze when the specific gravity drops as
a result of discharging. As can be noted
from the following graph, if the specific
gravity of the electrolyte is set at 1.26 or
so by proper charging, there will be no
fear of freezing even in winter. But it is
obvious that, when the specific gravity
falls to 1.15 (at approximately 50% of
discharge ratio), the electrolyte will freeze at -15°C (5°F).
The water in the electrolyte will be gradually consumed by evaporation or by

being decomposed into hydrogen and oxygen at the time of charging. It
decreases in volume several times faster in summer than in winter. If it
decreases to a point where the plates appear above the liquid level, not only
the battery capacity is reduced, but also the life of the battery is shortened.
Therefore, check the liquid level from time to time by removing the vent plug.
In the event the liquid level is below the specified level, replenish water. In
this case, bear in mind the following points of
caution.
- Replenish with distilled water or refined water (commercially available as

a battery replenisher). Do not use city water without distilling, or impurities in
it will shorten battery life.
- Do not replenish dillute sulfuric acid except when electrolyte has spilt out.
Since electrolyte reduces through evaporation of water in it, sulfuric acid will
get thick, thereby shortening the life of plates.
- In winter, it is safer to replenish water prior to operation. While water is apt

to freeze before it is mixed into the electrolyte, such fear is virtually
nonexistent as it will mix with the electrolyte during battery is charged by
the charging generator.
ELECTRIC POWER SPONTANEUOSLY DECREASE

You will get hungry even i£ you lie still or don't do anything. The same is true
of the battery which will spontaneously reduce the charge even if it is not
used. This is called the "self-discharge" or "spontaneous discharge" of
battery.
If a battery is left unused for an extended period of time, electric charge
reduces itself due to self-discharge, thereby damaging the battery. For this
reason, it is necessary to charge at least once a month in summer and once
every other month in winter. It is also necessary to keep it in a proper place
and to take good care of it in order to hold self-discharge to an absolute
minimum.
The battery is more apt to be self-discharge in summer than in winter.

Referring to the graph below, you will notice that amount of charge which is
reduced by self-discharge is more pronounced at increasingly higher
temperatures. Therefore, it is advisable to keep the battery in a cool and dry
place. It is utterly outrageous to leave batteries in a vehicle not in operation
for an extended period of time in summer. The batteries must be removed
from the vehicle and kept in a cool place. Also, do not forget to re-charge
them once a month.
- If a battery is covered with dust on it and
moistened by electrolyte, current, though
very slight, flows there. This will be often
the cause of self-discharge. It is therefore
necessary to keep the battery clean. If a
battery is dirty with electrolyte, it must be
wiped clean with a cloth immersed in
ammonia water to neutralize it.
- If a battery is damaged and particles of active substance come off from the
plates and settle on the bottom, current flows via those particles, thereby
causing battery self-discharge. The battery will run down very soon after re-
charging in an extreme case.
- Also, self-discharge is apt to develop it self when impurities in the
electrolyte increase, or when the specific gravity of the electrolyte becomes
greater.
When adding water to the electrolyte, make sure that all the points of caution
beforementioned are properly observed.
RECHARGE BATTERY WHEN IT RUNS DOWN
Even when you are hungry, eating too much will cause stomach trouble.
Recharging too much current at a time or excessive recharging will damage a
battery even when it runs down.
Connect the positive (+) terminal of a recharger to the positive (+) terminal
post on the battery and the negative (-) terminal of the former to the negative
(-) terminal post on the latter; apply higher voltage than the battery voltage to
make current flow into the battery. In this case, extreme care should be taken
not to make incorrect connection.
While recharging, the battery will show the following process -
Lead sulfate produced on the positive plates will gradually return to lead
peroxide; lead sulfate produced on the negative plates will gradually return to
lead.
The specific gravity of electrolyte increases and in time returns to the same
level observed before discharging, and when it returns perfectly, the
recharging has now been completed.
There are two different methods of battery recharging. one is the method of
recharging with constant current and the other is that of recharging with
constant voltage. When recharging a battery by means of a recharger, do so on
constant current, and when recharging it with a charging generator, do so on
constant voltage.
To recharge a battery on constant current, current of the order of one-tenth
of battery capacity should normally be used.
If this current is too large, heat built up during recharging will cause
temperature to go up too high, thus resulting bend of the plates or coming off
of the active substances. Consequently the battery suffers. In any case,
electrolyte temperature should be held to less than 45°C (113° F).
Although terminal voltage will rise up to

the considerably high level during
charging, it will go down to a level cor-
responding to the amount of electric
charge soon after the charging current is
discontinued.
The above graph shows the change of voltage appearing on a battery cell.
Initially, the voltage suddenly goes up and then climbs little by little until
about 2.3 V at which 80% recharge of capacity will be made. Then, voltage
will again start to go up fast. Now the water in the electrolyte is decomposed
to cause bubbles of oxygen and hydrogen to appear. These bubbles increase in

number with a rise in voltage. As charging period further goes on, the voltage
now does not go up as fast as before and finally stops further going up even if
recharging is continued, causing only bubbles. When this condition has been
reached, it indicates that the battery recharging has now been completed. So it
is necessary to stop recharging of battery at that point.
Should recharging is kept on, charging current will be wasted and excessive
recharging results, thereby damaging the battery.
Constant Voltage Recharging is generally accomplished by applying 2.3 or

2.4 V constant voltage per battery cell. During the recharging, current flows
most at the outset of recharging, but it will gradually flow less as the
recharging goes on. At the end of recharging, only very little current will flow.
Therefore, it will be difficult to fully recharge at the end, it in turn means that
there is no fear of excessive recharging.

Current is limited by operation of regulator, and the curve will be varied

as the adjustment of regulator varies.
When recharging a battery by means

of an engine-drive charging
generator, a regulator operates to
maintain output voltage of the
generator uniform. Any desired
voltage can be obtained by adjusting
the regulator. In this case, it should be
noted that loosened generator belt,
worn brush, improperly adjusted
regulator, etc. will cause insufficient power generation of the generator,
resulting in battery damage. Also, even if the generator sufficiently generates
power, use of many electrical equipment or improper contact of battery
terminals will cause lack of power for recharging the battery.
Although the battery is held in normally recharged state by a generator, each

battery cell will show, in the long run, an appreciable difference in
performance from others. For this reason, it is important to dismount the
battery from the vehicle and overcharge it 20% or so with a recharger several
times a year, or once a month if possible. By so doing, the battery life may be
prolonged consideravely.
A battery will not permit good flow of charging current at low temperature,
thereby resulting in the reduction of charging efficiency. In winter, therefore,
recharging will become difficult and more power is needed for recharging.
Therefore, it is important to keep the battery protected from cold weather. In
extremely cold weather, dismount the battery from the vehicle from time to
time to recharge it with a recharger, or keep recharging voltage a little high by
adjusting the regulator.

Furthermore, when it is desired to use any run down battery temporarily,

recharge it quickly with large current, making sure that battery temperature
does not go up to high. This is called "quick charging".
In addition, the "initial charging" method is also employed for putting a new
battery that has been kept empty without electrolyte in use. A description of
this method, however, is omitted fom this Training Aid.
Cautions to he observed when charging: As described in the preceding

pages, hydrogen gas will be produced from the electrolyte during battery
charging. If a flame is brought near the battery being charged, an explosion
will possibly take
place. Also, a description has been made to the effect that water should be
added when the electrolyte decreases. When charging is made with a
recharger, measurement and adjustment of the specific gravity is necessary
after the charging has been completed.

BATTERY LIFE
Human has his life expectancy. But if one does not take good care of
himself, his life can be shortened. The same is true of the battery. Improper
use will result in shortened service life.
The life of human comes to its end when he passes away. The life of battery
comes when the battery loses charging ability as sufficiently as before, or
when it runs out of current too soon. In other words, battery life ends when its
capacity is seriously reduced after repeated recharging and when the battery is
rendered useless.
Here, a question arises. How can we consider the battery as no longer
useful, or where can we stop using a battery, capacity-wise? Although this
cannot be determined easily, the Japan Industrial Standards state that any
battery being in test should be stopped further progress of its test when
battery capacity is reduced to 40%. This 40°Io is considered to be the very end
of battery life.

Well, then, why will come the end of battery life?

As the active substances coated on the battery plates come off gradually, the
amount of electricity to be charged will decrease, while the amount of self-
discharge current increases.
Incidentally, the active substances on the battery plates will gradually come
off after repeated rechargings. Especially, under the following conditions
great amount of active substances comes off increasingly, consequently
shortening the battery life:
- Over discharge or overcharge .
- High specific gravity of electrolyte
- Excessive flow of current or reverse charging
- Charging or discharging at high ambient temperature
The active substances on the battery plates change into lead sulfate when
discharging is made; they return to the working substances when recharging is
made. Normally lead sufate particles are of extremely small crystalloid. When
these particles become larger and no longer be impossible to return to small
particles as before; the battery cells lose their recharging charactor. When the
relatively large crystals are formed, they turn white. Old battery plates often
turn white for this reason. This is called sulfation. The following causes make
rapid progress of sulfation, therefore shortening the battery life.
- Over discharge .
- Non-use for an extended period of time Insufficient charge
- Lack of electrolyte or electrolyte contamination due to impurities
in addition, there are still a number of causes for premature service life of a
battery, including such causes as corroded plate and bent plate. All these
apparently result from improper use. Damaged battery container, frozen
electrolyte, etc. will also seriously affect the battery, thereby rending it
useless. These injuries can be compared to the loss of life by traffic accident.
IT IS IMPORTANT TO NOTE THAT THE LIFE OF BATTERY

DEPENDS LARGELY HOW YOU HANDLE IT.

CARE OF BATTERY HANDLING
As the electrolyte in the battery is deleted sulfuric acid, a cloth immersed in

the electrolyte during careless handling of battery will be soon tattered. If the
cloth should be covered with the electrolyte, immediately flush it with water
and neutralize it with ammonia water.
Dropping a spanner or the like onto the battery will cause short-circuiting,
permitting large current to flow through battery plates. Consequently, the
plates will be bend, resulting a serious damage of the battery.
It is very unwise to check the charging state of a battery by shorting it with a
screwdriver or the like. If the battery is being recharged at that time, the
resulting sparks may cause a serious explosion.

Inadequate tightening of terminals, corroded terminals, or improper

electrical contract will not permit normal flow of the current, thus, often
resulting in unexpective trouble such as difficult engine starting and lack of
battery charging. Therefore, when rust exists on the terminals, thoroughly
wash and polish them and firmly tighten them down. Furthermore, apply a
film of grease to prevent their surface from being corroded.
It should be fully recognized that improper contact of terminals will cause

considerable voltage drop at the time of engine starting. To be more precise,
suppose now that 300-ampere current flows across the resistance of 0.005
ohms, the voltage will fall by 1.5V. This will cause no small slow-down of
starting motor revolution.

When disconnecting cords from the respective terminals, first remove one
being grounded to the vehicle's chassis, then remove the remainder. When
connecting the cords, reverse the disconnecting procedure. Keeping in this
order is necessary to avoid any danger results from an electrical shorting
which is apprehended during handling of the cords.
When connecting terminals, care should be taken to use cords of sufficient

length. This is to preclude the possibility of battery terminals being pulled
strongly or of battery being cracked on the surface.
After making the terminal connection, do not immediately start the engine
but make sure terminals to see if they are properly polarized.
If the ammeter mounted on the vehicle's dashboad deflects from center to "-
" (or "D") side when the lightening switch is turned on, it indicates that the
terminals have now properly been connected.

In order to ensure proper use of a battery, it is important to keep the following

keypoints in mind.
- Recharge the battery whenever the specific gravity of electrolyte has fallen
to about 1.20.
- Avoid over-charge or over-discharge. Particularly be carefull of over-
discharge in winter.
- Do not try to turn the starting motor for long even if the engine does not
start.
- Since the self-discharge occurs even when the battery is out of use, recharge
the battery in storage from time to time.
- When the electrolyte level goes down below the specified level, replenish by
adding distilled or refined water, making sure that no impurities are allowed to
contaminate in the water.
- Keep the surface of the battery clean at all times. Never leave it covered with
spilled electrolyte or dust.

Larutan Elektrolit.
Larutan elektrolit ini terdiri dari pencampuran antara Asam Sulfat ( H2SO4 )
yang berat jenisnya 1,835 dan air ( H2O ) yang berat jenisnya 1 dengan
komposisi tertentui seperi gambar berikut ini :
+ =
H2O
H2SO4
64 % WATER 36 % ACID ELECTROLYTE

SP.GR. = 1.000 SP.GR. = 1.835 SP.GR. = 1.27
Gbr. Komposisi elektrolit battery.
Hasil campuran 36% asam sulfat dan 64% air akan menghasilkan
elektrolit yang berat jenisnya 1.270 pada 80º F ( 27ºC ).

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BATTERY FUNDAMENTALS

Early Rechargeable Battery

Mechanic Development ADVANCE ELECTRIC 1

If a uniform current is continuously

As the final terminal voltage when measuring 20-hour discharge rate

Furthermore, 20-hour discharge rate capacity of battery is based on the

Mechanic Development ADVANCE ELECTRIC 3

WHEN WEATHER IS COLD, ELECTRIC POWER CAN NOT BE

The beside graph is plotted with the

Mechanic Development ADVANCE ELECTRIC 5

RUN FASTER, QUICK COMES FATIGUE

Consequently, when using current of the order of several hundreds

Mechanic Development ADVANCE ELECTRIC 7

Mechanic Development ADVANCE ELECTRIC 8

Mechanic Development ADVANCE ELECTRIC 9

Referring to the graph, if the specific gravity of the electrolyte is 1.260

Mechanic Development ADVANCE ELECTRIC 10

The specific gravity of the electrolyte increases in proportion to a drop in

The electrolyte is rendered easier to

The water in the electrolyte will be gradually consumed by evaporation or by

- Replenish with distilled water or refined water (commercially available as

- In winter, it is safer to replenish water prior to operation. While water is apt

ELECTRIC POWER SPONTANEUOSLY DECREASE

The battery is more apt to be self-discharge in summer than in winter.

Although terminal voltage will rise up to

to cause bubbles of oxygen and hydrogen to appear. These bubbles increase in

Constant Voltage Recharging is generally accomplished by applying 2.3 or

Mechanic Development ADVANCE ELECTRIC 18

Current is limited by operation of regulator, and the curve will be varied

When recharging a battery by means

Although the battery is held in normally recharged state by a generator, each

Mechanic Development ADVANCE ELECTRIC 20

Furthermore, when it is desired to use any run down battery temporarily,

Cautions to he observed when charging: As described in the preceding

Mechanic Development ADVANCE ELECTRIC 21

Mechanic Development ADVANCE ELECTRIC 22

Well, then, why will come the end of battery life?

IT IS IMPORTANT TO NOTE THAT THE LIFE OF BATTERY

Mechanic Development ADVANCE ELECTRIC 24

CARE OF BATTERY HANDLING

As the electrolyte in the battery is deleted sulfuric acid, a cloth immersed in

Mechanic Development ADVANCE ELECTRIC 25

Inadequate tightening of terminals, corroded terminals, or improper

It should be fully recognized that improper contact of terminals will cause

Mechanic Development ADVANCE ELECTRIC 26

When connecting terminals, care should be taken to use cords of sufficient

Mechanic Development ADVANCE ELECTRIC 27

In order to ensure proper use of a battery, it is important to keep the following

Mechanic Development ADVANCE ELECTRIC 28

64 % WATER 36 % ACID ELECTROLYTE

Gbr. Komposisi elektrolit battery.

Mechanic Development ADVANCE ELECTRIC 30

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