with a bituminous material
1 cell is composed of several
by a wood or microporous
om of the container leave a
collect during the useful life

Jead-alloy grid into which
med electrolytically so that,
le. Similarly, the negative
lead oxides are pasted and
it the oxides are converted
f a water solution of sulfuric
sharged state of about 1.28

ttery at the beginning of its
m of a battery at the end of
plates are corroded and the
ie negative plates have lost

‘motive battery at end of life.

orage battery at end of useful life.
ive,

some of their active material and are badly sulfated. The wood
separators are charred by the sulfuric acid, and active material is
deposited on their surfaces. Figure 3 shows the condition of the
positive plates and negative plates. The positive grid frame is
corroded to such an extent that the plate is disintegrated. The
negative plate has lost some of its active material in the sulfated area.

II. Fundamental facts about storage batteries

Astorage battery may be considered as an electrochemical apparatus
in which electric energy is stored as chemical energy. :

When a storage battery is discharged the chemical energy. is trans-
formed into electric energy as the lead dioxide and sponge lead react
with the sulfuric acid to form lead sulfate at both the positive and.
negative plates. The current flows from the positive to the negative
plate externally and from the negative to the positive plate internally
to complete the cycle of transformation of chemical energy into
electric energy.

The lead sulfate formed during the discharge forms a surface coat-
ing over most of the surface of each particle of finely divided sponge
lead or lead dioxide. The center of the particle, being nonporous, is
not converted to lead sulfate. Each particle is in intimate contact
with the next particle so that electrically continuous flow of current
is maintained. Thus this normal deposit of lead sulfate forms a
relatively thin film over the particles of active material and is easily
reconverted to the corresponding lead or lead dioxide during subse-
quent recharge. The relative size of these particles determines the
amount of electrolyte that may be in the pores of the plate at any
given time.

If a battery is subjected to a high rate of discharge, the reaction of
the lead and lead dioxide with sulfuric acid will be very rapid. This
tends to weaken the layer of acid close to the surface of each particle,
thus limiting the continuous discharge capacity. However, if the
discharge is stopped for a short period and then repeated, the battery
will give additional performance. Thus it may appear to the layman
as if it has automatically charged itself. This may be repeated a
number of times with each succeeding discharge, giving poorer per-
formance until the battery is effectively completely discharged. This
phenomenon, which has been known for 70 years, is inherent in all
storage batteries and is known as the recuperative power of the lead-
acid battery. Each time the battery is rested the acid diffuses into
the pores of the plate and replenishes the supply of acid at the surface
of the particles of active material.

After the battery has been discharged it is charged by forcing an
electric current in the opposite direction so that the lead sulfate is
converted back to lead dioxide and sponge lead according to its original
condition. This completes the cycle in which chemical energy fur-
nishes electric energy and electric energy is again stored as chemical
energy.

The word “charge” as applied to storage batteries is defined as
follows in the Standards for Storage Batteries adopted by the Ameri-
can Institute of Electrical Engineers, dated June 22, 1922 (Definition
No. 36-250):

“Charge.—The conversion of electric energy into chemical onerpy
within the cell or battery. This consists of the restoration of the

3



1 ____/0
40 50 60
Ss

current during the first hour of a
ged battery.

se, this essentially resolves
ilt will be the same with or

y to play a part in the over-
e plates are exposed to air.
lace that changes the com-
ad oxides and sulfate. In
s are more easily converted
1 of water or low-gravity
ne battery responds equally
ich a procedure the battery
mately 50 hours.

its

sed on simulated tests made
m the correctness of these
y the Ordnance Corps, De-
batteries at various depots
oups of batteries were all
3 of life, as follows: (1) 50
ries still in service, (3) 50
id (4) 50 batteries new but

) were treated with mixture
controls. Monthly checks
the batteries. The results
d44. Table 42 summarizes
ecific gravity, and table 44
performance. From these
no beneficial effects gained

Tanum 42, Number of failures out of 0 batteries in each group when treated with
‘mixture C and field tested for 6 months

‘Months ‘Total
per
Stale
of faile
1) 2{3|4]5|6 )°ue

Battery condition

‘Mechanically sound, but ready for salvage (treated)
‘Mechanieally sound and still in service (treated)
‘New batteries never prepared for service (treated!
‘New batteries never prepared for service (untreat

onwe
econo
wo tbat

Tantm 43. Percentage variation in specific gravity at end of 6-month period on
batteries treated with mixture C

Groups, | Group 2, | Group3, | Group 4,
Treated’ | “eated’ | treated’ | untreated
% % % %
Fee 2 8 46
2 3 21 9
2 6 4 a

vTanum 44, Percentage of satisfactory and unsatisfactory batteries after inspection
at 6-month period on batteries still in service

; Group 1, | Group 2, | Group 3, | Group 4,
Condition ireated’ | ‘treated’ | treated’ | untreated
% % % %
# B a 6
58 55 36

VIII. Conclusions

In the course of this investigation five batteries comprising 15 cells
were subjected to an extended series of laboratory tests to determine
the effect of adding specified amounts of sodium and magnesium sul-
fates in varying proportions. These batteries were in sound mechan-
jeal condition but were sulfated to the extent that their initial capacity
after prolonged charging was about two-thirds of their rated capacity.
Ten cells were treated with additives, and the remaining five were
not treated.

Tables 4 to 31 show no significant differences in the operating
characteristics of the cells that were treated as compared with those
not treated. Obviously, the condition of a group of batteries ina
sulfated state is not uniform, but the average results of 15 cells cover-
ing all tests show a remarkable uniformity in the behavior of treated
‘and untreated cells. The averages are given in table 45.

It appears from table 45 that both sodium and magnesium sulfates
are ineffective in improving the condition of the batteries or in pro-
longing their life.

29



i several leaflets during the past
[any of these additives have been
ery failures. These leaflets were
ds of inquiries about such mate-
ired, and the present is an oppor-
oased on recent tests. This Cir-
wrative tests that these materials
sts of storage batteries or battery
ecasion in the past to make tests

nobile owner and storage battery

E, U. Connon, Director.

+
|
i
|

¢

Battery Additives

Paul L. Howard and George W. Vinal €

Various preparations of liquids and solids have déen sold to the public as
means of rejuvenating worn out or so-called “dead” batteries. The majority
of these materials are composed of varying proportions of magnesium sulfate and
sodium sulfate. Extensive laboratory and field tests have been made covering
various proportions of magnesium and sodium sulfates, The results show no
difference between the batteries treated with these mixtures and similar untreated
batteries used as control.

I. General description of lead-acid storage battery

Figure 1 shows a cutaway view of an ordinary automobile battery.
Three cells are housed in a hard-rubber or composition container
and covered with tops of similar material containing filler wells,

RD RUBBER
_ CONTAINER

Frievre 1. Cross-sectional view of standard automotive battery.



tional current through the cell or
that of the discharge. A cell or
zed” is understood to be fully

follow the fundamental electro-
‘be stated as follows:

t free at an electrode is directly
‘tricity that passes through the

y sets free the same number of
trodes.

‘al reactions within the storage
in electrolyte brought about by

ation

d in several senses, and this has
, it means the formation of lead
es of the active material of the
sult of (1) normal discharge, (2)
se.

nal discharge results in a fine
les of active materials. This
charging current. This type of
eration of a battery and is not a

1 is caused by parasitic currents
ubstances present. The rate at
s upon the temperature and con-
ormation of lead sulfate in this
normal discharge process. This
ever, if the battery is not neg-
verted to active material by the
automobile battery the average
fic-gravity change) for different
drop per day at 100° F, 0.002
‘day at 50° F.
1e battery would need recharging
lowing intervals: At 100° F re-
‘t 37 days, and at 50° F recharge
the electrolyte will increase the
fation in the plates.
ord sulfation applies to excessive
1 in or on the plates as a result of

in a discharged condition for a
n evidence of trouble within the

*n water should have been used.
emperatures.

the electrolyte.
a partially charged condition.

This type of sulfation is more difficult to reduce and may injure the
plates. Excessive sulfation can be avoided with reasonable care. It
is doubtless true that the liability to troublesome sulfation of lead
batteries has been exaggerated by those exploiting so-called cures.

When a battery stands in a discharged condition for some time the
lead sulfate crystals tend to grow. In doing this they harden and
become larger and may break away from the surface. Also, the
growth of the sulfate crystals tends to block the pores of the plate.
As these crystals occupy more space than the original active material,
their expansion may eventually either fracture the grid frame or
loosen the active material. .

Lead sulfate is very slightly soluble in sulfuric acid ‘electrolyte at
normal temperatures. However, the solubility increases with rise in
temperature. One cause of crystal growth depends on a rise in
temperature to dissolve the lead sulfate and a drop in temperature to
recrystallize it. Thus the larger crystals grow at the expense of the
smaller. Another cause is the removal of acid from the electrolyte
in the pores as lead sulfate is formed, causing a greater solubility of
the lead sulfate in the low gravity acid and a recrystallization as more
acid diffuses into the pores or as the amount of electrolyte in the
pores is reduced due to growth of the crystals. Both of these causes
contribute to troublesome sulfation.

Because of the closing of the pores in the active material by the
crystal growth of the lead sulfate it becomes increasingly difficult for
the electrolyte to penetrate into the plates. If a battery which has
stood for along time is filled with water and placed on charge with a
direct-current source it is found that the initial closed-circuit voltage
is much in excess of its normal value. As the electrolyte penetrates
into the active material and reconversion begins the voltage will
gradually drop to that of a normal cell. If the applied voltage is low
and the cell resistance is high, the indications might be that the cell
is dead. However, if sufficient time is allowed, there would be a
gradual} break down of active material and current would begin to

low. ‘This condition is true, regardless of whether or not a battery
has been treated with additives, provided it has been in a sulfated
condition for a long period.

IV. Types of additives

More than 100 additives have been brought to the Bureau’s atten-
tion during the past 30 years. A statement entitled “Solutions do
not charge storage batteries” was issued in the Bureau’s Technical
News Bulletin 94, February 10, 1925. Since that time many addi-
tional tests on solutions and compounds, the latter in the form of
salts to be added to the battery electrolyte, have been made. Bureau
Letter Circular 302 was issued in 1931 and has been revised to meet
new demands.

Various types of additives have been marketed over the period of
years. Analysis of these preparations shows their composition falls
into the following categories:

Solids:

(1) Preparations of varying proportions of magnesium sulfate and
sodium sulfate in various states of hydration.



ests, tables 4 to 81

Untreated cells ‘Treated cells

120 amp-hr

48 amp-br.
4 amp-br.
Lizy,

03 Vv.
59 ml/woek.
0.007.

tests covered in this inves-
een no improvement found
pecially prepared additives
es either hydrated, partially

utions and compounds to a
e cases no particular harm
neiple in battery operation
that which has been spilled
fic gravity to the required
wge. Materials containing
‘lycerine, or alcohols should
ause permanent damage to

ned to the Bureau’s experi-
es, both Government and
sions on the various points

2s

lead storage battery, Residual
xc. Japan 8, 16~20 (1940).
mage batteries, Chem, Fabrick.

ler wahrend u. nach langerer,
191 (May 1949).

hate and the thickness of the
mpt. rend. 81, 581-4 (1941).

te of self discharge of lead acid
365-71 (1942).

sulphate in solutions of sulfurie
J. Research NBS 22, 55 (1939)

vitery electrolytes, Trans. Am.

5. GOVERNMENT PRINTING OFFICE: 1954

|
i

Published Recently ......
CARE AND REPAIR OF THE HOUSE

A 209-page guide for homeowners, Care and Repair of the House,
presents up-to-date information on the maintenance of houses and
on the most recent materials and construction methods for repairs.

Care and Repair of the House discusses in nontechnical language the
causes of wear and deterioration, preventive measures, and the
simplest methods for making repairs. Included are chapters on
foundation walls and basements, exterior walls, interior walls, roofs,
floors and floor coverings, doors and windows, weatherproofing and
insulation, heating and ventilating, plumbing and water systems,
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the house tells how to detect signs of wear before slight problems
develop into major repair jobs.

Order NBS Circular 489, Care and Repais of the House, 209 pages,
illustrated, from the Superintendent of Documents, U. 8. Govern-
ment Printing Office, Washington 25,D.C. Price: 50 cents a copy.



NBS CIRCULAR JOZ

Battery Additives

UNITED STATES DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS



n, aluminum, calcium, or
: phosphate salts.

) and (2), nitrates, chlorides,
nt. All these are definitely

us specific gravities, with or

ious specific gravities, with
erials containing some or all
esium, potassium, aluminum,

ye and traces of metal salts.
is of organic acids or metallic

‘tion with or without metal

additives specify that each
contents of a package, filled
utomobile generator for a cer-
st is usually given in which
til it will no longer turn the
nition is turned on and the
ong enough to start it.

condition of the battery or
aracteristics of the battery,
urchaser a false idea that an
litive. Preliminary tests are
nprovement in performance

complete study of the effect
alete check on the character-
> and after treating to estab-
‘k to the types of additives
drawn from earlier work.
ons are concerned it is known
iined through increasing the
mentarily there may be an
sal action associated with the
e this advantage.

laterials shows no advantage
ery. If glycerin or alcohols
ul as they are converted to
n the electrolyte and shorten

pper, mercury, iron, nitrates
wn in the work of Vinal and

ommonly used materials are
Combinations of these sub-
mt-day additives.

V. Experimental Procedure

In order to study these combinations it was necessary to devise a
test procedure that would cover the main characteristics of the battery
and the claims most often used by the manufacturers for their additive.
A series of tests was set up to cover the following points:

1. Change in specific gravity of solution produced by the additive.

2. Effect on capacity at normal discharge rates, such as the 5-hour
rate, to determine whether there was a decrease in sulfation.

3. Effect on self-discharge or local action as an indication of im-
provement in retention of charge. :

4, Effect on temperature of cells during charge as a ‘means of
prolonging life.

5. Effect on water consumption as an indication of whether the
battery was taking the charge better with or without the treatment.

6. Simulation of an operational test where the batteries remained
just under full charge for a long period but never on a complete dis-
charge cycle to determine whether the treated cells would recharge
more completely than untreated cells.

7. High-rate discharges starting at 300 amp then reducing to 200
amp and 100 amp successively to determine whether there is any
change in cell performance under these conditions by treating the
battery with additives.

8. Determination of the recuperative power of a cell when subjected
to 300-amp load for a short interval followed by a rest period and
repetition of the"eycle. “This is to indicate whether any improvement
was made by the treatment.

9. Effect of several complete cycles to see if there was an increase
in capacity and specific gravity.

In order to make such a series of tests it was first necessary to obtain
mechanically sound batteries that were permanently sulfated. Vari-
ous so-called sulfated batteries were obtained and given a charge for
an extended period until there was no further change in gravity. A
battery made in 1920 that had been allowed to stand from then until
1949 was dismantled and the negative plates charged in 1.050 specific
gravity sulfuric acid against sheet-lead positives. These plates were
completely converted to sponge lead. Tt has been the experience here
that most of the so-called sulfated batteries filled with low-gravity
sulfuric acid or water will respond to normal charging procedures,
provided the charge is slow and over an extended period. However,
if the cells are filled with high-gravity acid, the response to charge is
very poor.

Six batteries of Army 6-volt type 2H that had stood for 4 years in
a charged and damp condition were filled with 1.050 acid and given a
388 amp-hr charge. The results of this charge are shown in table 1.
Here the specific gravity did not rise equally in all cells and the
capacity was low except in battery 5. This battery recovered all its
rated capacity but was high in local action.

Capacity and stand loss were measured on these batteries to estab-
lish their characteristics prior to treating. A series of combinations
of anhydrous magnesium and sodium sulfates were set up as shown in
table 2. Mixtures A and C are commercial products, while mixtures
B, D, and E were prepared and included in the group in order to
extend the range of compositions studied.

911373~51—2 7



UNITED STATES DEPARTMENT OF COMMERCE + Charles Sawyer, Secretary
NATIONAL BUREAU OF STANDARDS ¢ E. U. Condon, Director

Battery Additives
by

Paul L. Howard and George W. Vinal

asive tests at the
lation of the w

reezes, 16 pages, ill
oS: ‘Government
ants a copy.

National Bureau of Standards Circular 504
Issued January 10, 1951

For sale by the Superintendent of Documents, U. 8. Government Printing Office
Washington 25, D. C. - Price 15 cents

—



UNITED STATES DEPARTMENT OF COMMERCE « Charles Sawyer, Secretary

NATIONAL BUREAU OF STANDARDS ¢ E, U. Condon, Director

Battery Additives

by

Paul L. Howard and George W. Vinal

National Bureau of Standards Circular 504
Issued January 10, 1951

For sale by the Superintendent of Documents, U. S. Government Printing Office
Washington 25, D. C. - Price 15 cents