Additive for electrolyte of lead-acid batteries

A new type of additive to be added to the electrolyte of lead-acid storage batteries to improve their operation, such as chargeability and startability, comprising a mixture of an iron chelate and a magnesium salt or chelate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a new type of additive for the electrolyte of 
lead-acid storage batteries. More particularly, the invention relates to 
new additives for the electrolyte of lead-acid storage batteries which 
greatly improve the efficiency of the operation of the said batteries. 
Specifically, the invention provides a new type of additive composition to 
be added to the electrolyte of lead-acid storage batteries which greatly 
improves their operation, particularly as to chargeability, startability, 
especially at the low operating temperatures, and reduces gasing effect 
and corrosion at the battery poles, said additive comprising a mixture of 
an iron chelate and a magnesium salt or chelate, preferable contained in 
an aqueous solution. 
The invention further provides a preferred method for preparing the new 
additives comprising adding a substantially water-soluble chelating agent, 
e.g. one prepared from a donor group containing O or N, and an iron salt, 
and preferably ferrous sulfate, to water so as to effect formation of an 
iron chelate and then adding the magnesium salt or chelate to the aqueous 
solution. 
2. Prior Art 
Lead-acid storage batteries are commonly used through out the world in 
various types of automobiles, carts and trucks. While they are highly 
effective in most climates, their use in the colder climates has certain 
limitations. It has been found, for example, that when temperatures are 
lowered to certain levels, they become sluggish and difficult to operate. 
This renders the automobile or truck difficult to start without the use of 
special charging equipment. In addition, the batteries have problems in 
the hot climates, wherein the gasing effect causes corrosion of the 
battery terminals and cables which shorts out the battery. 
Furthermore, many of the lead-acid batteries are now being used on golf 
carts, trucks, toys and recreation vehicles where there is no source of 
regeneration, and it is necessary to recharge the batteries after a period 
of time. Such recharging is time consuming and expensive. 
Finally, such batteries have limited source of energy and in many cases are 
accidently discharged leaving the operator stranded. The only solution at 
the present has been to take the battery to a location where it can be 
recharged or to replace the battery with one that has been charged. This 
in many cases causes expensive delays. 
Various additives have been suggested for addition to the electrolyte to 
solve many of these problems. In all such cases, however, the additive has 
had little or no effect or has caused additional problems in the operation 
of the batteries. For example, such additives have included metal salts 
but these have in many cases given only slight improvement in activity, or 
have given only temporary increase of activity, and subsequently have 
caused contamination of the lead plates and premature loss of activity. 
It is an object of the invention, therefore, to provide a new and improved 
additive for increasing the efficiency of lead-acid batteries. It is a 
further object to provide new additives for the electrolyte of lead-acid 
batteries which increases the efficiency of the said batteries, 
particularly during the colder temperatures. It is a further object to 
provide new additive compositions for electrolyte of lead-acid batteries 
which increase the rate of charging said batteries. It is a further object 
to provide new additive compositions which increases efficiency of both 
old and new type lead-acid batteries. It is a further object to provide 
new additive compositions for electrolyte of lead-acid batteries which 
causes a decrease in the gasing effect and thereby reduces possibility of 
corrosion of the terminates and cables. It is a further object to provide 
additives for the electrolyte of lead-acid batteries which increases the 
period of activity of the said battery over a wide range of temperature 
conditions. These and other objects of the invention will be apparent from 
the following detailed description thereof. 
SUMMARY OF THE INVENTION 
It has now been discovered that these and other objects may be accomplished 
by the new additive compositions of the present invention comprising a 
mixture of an iron chelate and a magnesium salt or chelate, preferably 
where the iron and magnesium are in a mole ratio varying from 0.1:1 to 
2;1, said mixture preferably being contained in an aqueous solution. 
It has been surprisingly found that the above-described additive 
composition imparts unexpected and superior properties to the lead-acid 
battery when added to the electrolyte thereof. It has been found, for 
example, that when the additive is added to the conventional sulfuric acid 
electrolyte of a new uncharged battery, the time to charge the battery to 
full charge is surprisingly reduced, even to about 1/2 the time normally 
required to charge the battery. It has been further found that batteries 
containing the new additive have surprising increase in efficiency of 
operation, even at the very low temperatures at which normal batteries are 
very sluggish or totally inactive. It has been found, for example, that 
batteries containing the additive show excellent activity even at 
temperatures as low as -30.degree. F. and are able to give instantaneous 
activity to start automobiles at that low temperature where the normal 
batteries take several minutes of sluggish activity to start the 
automobile. Further unexpected advantage is found in the fact that the new 
additive greatly reduces the gasing effect i.e. release of bubbles of gas 
at the terminal plates, which thereby reduces the formation of corrosion 
at the terminals or cables of the battery. It has also been found that the 
new additive renders the battery more resilient on unexpected discharge as 
such batteries, when left to stand for a period of time, recharge 
themselves to a point where they regain part of their lost efficiency. 
Batteries containing the new additive also demonstrate much longer life 
span than those which do not contain the additive but contain only the 
conventional 35% sulfuric acid electrolyte. 
DETAILED DESCRIPTION OF THE INVENTION 
The new additives of the present invention comprise a mixture of an iron 
chelate and a magnesium salt or chelate, preferably wherein the iron and 
magnesium are in a mole ratio varying from 0.1:1 to 2:1 and said mixture 
preferably being contained in an aqueous solution. 
The iron chelate may be obtained by reacting any iron salt with any 
suitable chelating agent, i.e. any material known to form complexes or 
coordination compounds with the iron ions. The electron-pair bonding 
formed between the electron accepting iron and the electron-donating 
chelating agent may be essentially ionic or essentially covalent depending 
on the donor atoms involved. The preferred chelating agents are those 
having donor groups containing non-metallic elements of Groups V and VI of 
the Periodic Table of Elements, and those containing N and O are the most 
common examples. 
Examples of such chelating agents include, among others, the acid, such as 
malonic acid, diethylmalonic acid, isopropylmalonic acid, oxalic acid, 
o-phthalic acid, succinic acid, maleic acid, citraconic acid; amines, such 
as ethylenediamine, N,N'-dimethylethylene diamine, diethylenetriamine, 
triethylenetetramine, propylenediamine, triaminotriethylamine; aromatic 
amines, such as bipyridyl, phenathroline, 5-chloro-1,10-phenanthroline, 
5-phenyl-1,10-phenanthroline,; natural amines and peptides, such as 
alanine, glycylalanine, asparagine, aspartic acid, glycine, glycylglycine, 
glutamic acid, histidine, leucine, methionine, phenylalanine, proline, 
tryptophan, tryrosine, valine; amino acids, such as 
beta-alanine-N,N-diacetic acid, 2-aminobenzoic acid, N,N'diacetic acid, 
beta-aminoethylphosphinic acid, N,N-diacetic acid, ammoniadiacetic acid, 
ammoniatripropionic acid, anilinediacetic acid, 2-sulfo-anilinediacetic 
acid, 1,2-diaminocyclohexane-N,N'-tetraacetic acid, 
ethylenediamine-N,N'diacetic acid, ethylenediamine tetracetic acid, 
N-benzylethylenediaminetriacetic acid, ethylenediaminedipropionic acid, 
ethylenediaminetetrapropionic acid, glycine-N-propionic acid, 
trimethylenediamine tetracetic acid, tetramethylenediamine tetraacetic 
acid, pentamethylenediamine tetracetic acid; hydroxy-substituted acids, 
such as citric acid, lactic acid, salicyclic acid, tartaric acid; 
condensate phoshates, nitro acids, salicyaldehydes and derivatives, 
beta-ketones and derivatives, phenols, such as 3,5-disulfophyrocatechol, 
8-hydroxyquinoline, and various porphyrins, such as protoporphyrin, 
dihistidine protoporphyrin, dipyridine protoporphyrin, various globins, 
and other heme proteins, enzymes and the like. 
Particularly preferred are the organic chelating agents, i.e. those having 
the donor groups within an organic group or groups, and ones which form 4 
to 6 membered rings with the iron, and which contain N and/or O groups, 
such as amine, acid, phenol or aldehyde groups. 
Coming under special consideration are the aliphatic amines containing up 
to 25 carbon atoms, and particularly the special alkylene amine alkanoic 
acids, such as for example, ethyleneamine acetic acids, such as diethylene 
diamine tetracetic acid, trimethylene diamine tetracetic acid, diethylene 
diamine tetrapropionic acid, and tetraethylene diamine tripropionic acid. 
Coming under particularly concern because of the superior results obtained 
therewith are the polyalkylene polyamine polyalkanoic acids containing up 
to 18 carbon atoms. 
The iron salt used in the preparation of the iron chelates may be any 
suitable ferrous or ferric salt, such as a sulfate, oxalate, phosphate, 
citrate, phthalate, and the like, but is preferrable a ferrous salt, such 
as a sulfate, oxalate or citrate salt. Coming under special consideration 
is ferrous sulfate and its various forms such as ferrous sulfate 
heptahydrate. 
The magnesium salt used in the preparation of the new additives of the 
present invention may be any suitable water soluble salt, such as 
magnesium sulfate, magnesium chloride, magnesium chromate, magnesium 
perchlorate, magnesium thiosulfate, and the like. Particularly preferred 
is magnesium sulfate and its various forms as now available. 
The magnesium may also be added in the form of a chelate. The magnesium 
chelate may be prepared in the same manner as described above for the 
preparation of the iron chelate with the exception that a magnesium salt 
may be used in place of the iron salts. Particularly preferred magnesium 
salts to be used in this case include, among others, the sulfate, oxalate, 
phosphate, citrate, phthalate, and the like salts. 
The iron chelate and the magnesium salt or chelate are combined by merely 
mixing the two components together in a suitable range of proportions. In 
general, the two components are combined so as to have the iron and the 
magnesium in a mole ratio varying from about 0.1:1 to 2:1, and more 
preferably in a ratio of 0.33:1. 
While the additives of the invention may be prepared by mixing preformed 
solid iron chelate with the solid magnesium salt or chelate, and using the 
powdered mixture as the additive, the additive is more preferably prepared 
as an aqueous solution according to the following preferred preparation 
method. 
The desired chelating agent as described above is preferably added to 
distilled water to form an aqueous solution thereof and the desired iron 
salt added thereto so as to form the iron chelate. The amount of the 
chelate added is preferably such as to form a complex with all of the iron 
in the iron salt. While the formation is completed at room temperature, 
heat may be applied so as to speed the formation of the complex. 
Preferably the mixture is heated to about 150.degree. F. to speed the 
reaction and bring about more complete complexing. 
The desired magnesium salt or chelate is then added to the aqueous solution 
containing the iron chelate. The amount added should be sufficient to 
maintain the iron and magnesium in the desired mole ratio as noted above. 
While the aqueous solution of the mixture can be used directly as the new 
additive, it is sometimes desirable to add some aqueous sulfuric acid, 
e.g. 35% sulfuric acid as contained in conventional battery electrolytes, 
to effect dilution of the additive composition before being added to the 
battery. 
The new additive compositions of the invention prepared as noted above are 
then added directly to the electrolyte of each of the cells of the 
lead-acid storage batteries. The amount added to each cell may vary over a 
wide range depending upon the type of battery, age of the battery and 
desired results. When employing the additives added as an aqueous 
solution, as prepared above, one preferably adds from about 1.25 to 2 U.S. 
fluid ounces of the prepared solution to each of the cells. 
After the additive has been added directly to the electrolyte of each cell, 
the battery may then be put into operation in the auto, truck, etc. as the 
effect of the additive appears almost instantaneous. While the mechanism 
involved is not understood, it has been projected that the chelate mixture 
greatly facilitates the passage of the current through the electrolyte and 
thereby increases the efficiency of operation as noted above.

To illustrate the manner in which the invention may be carried out, the 
following examples are given. It is to be understood, however, that the 
examples are given in the way of illustration and are not to be regarded 
as limiting the invention in any way. 
EXAMPLE I 
This example illustrates the preparation of the new additive of the 
invention, and its use in increasing the efficiency of a lead-acid storage 
battery. 
0.8 Grams of ethylene diamine tetracetic acid (0.0027 moles) was added to 
169.7 grams of distilled water (9.43 moles). This mixture was stirred and 
then 3.0 grams (0.02 moles) of ferrous sulfate heptahydrate was added to 
the mixture. The combined mixture was stirred at room temperature until 
the components had dissolved. 7.0 Grams (0.058 moles) of magnesium sulfate 
was added to the mixture which was stirred at room temperature. The 
mixture was then added to a new container and 133 grams of 35% sulfuric 
acid added. The resulting solution making up the new electrolyte additive 
appeared as a fluid substantially clear liquid (appox. 302 cc). 
The use of the above prepared additive solution to increase the 
chargeability of lead-acid storage batteries is illustrate in the 
following experiment. 
Two new 12 volt 6 cell lead-sulfuric acid storage batteries were obtained 
without the electrolyte. To both batteries was added the standard 35% 
sulfuric acid solution allowing room at the top of each of the cells of 
one of the batteries (Battery A) for the addition of the additive, while 
the acid solution was added to the top of each of the cells of the other 
battery (Battery B). 1.5 U.S. fluid ounces (44 cc) of the additive 
prepared above was then added to each of the cells of Battery A. Both 
batteries were then subject to charge. Battery B without the additive was 
fully charged in 7 hours, while Battery A with the additive was fully 
charged in only 21/2 hours. 
EXAMPLE II 
This example illustrates the ability of the new additives of the present 
invention to increase the startability of the storage batteries at low 
temperatures. 
9 Fluid ounces of the new additive was prepared as shown in Example I 
above. 1.5 Fluid ounces of this solution was added to each of the cells of 
a new 12 volt 6 cell lead-sulfuric acid storage battery which had been 
fully charged (Battery A). Another new 12 volt 6 cell lead-sulfuric acid 
battery containing standard 35% sulfuric acid electrolyte without additive 
(Battery C) was also fully charged. Both batteries were placed in 
automobiles and maintained for 48 hours at an average temperature of about 
-15.degree. C. Attempts were then made to start both automobiles. The 
automobile containing Battery A with the additive added started 
immediately, while the automobile containing Battery C without the 
additive barely started after about 3 minutes. 
EXAMPLE III 
This example further illustrates the ability of the new additives to 
increase the startability of the storage batteries at low temperatures. 
9 Fluid ounces of the new additives was prepared as shown in Example I 
above. 1.5 Fluid ounces of this solution was added to each of the cells of 
a 1 year old 12 volt 6 cell lead-sulfuric acid storage battery containing 
conventional 35% sulfuric acid electrolyte and was fully charged (Battery 
B). Another 1 year old 12 volt 6 cell lead-sulfuric acid battery 
containing standard 35% sulfuric acid electrolyte without additive 
(Battery D) was also fully charged. Both batteries were placed in 
automobiles and maintained 24 hours at an average temperature of 
-30.degree. C. Attempts were then made to start both automobiles. The 
automobile containing Battery B with the additive started immediately even 
at that low temperature. The automobile containing Battery D reacted very 
sluggishly and finally started after about 2 minutes. 
EXAMPLE IV 
This example illustrates the ability of the new additives of the invention 
to rate of recoverability of the power of a storage battery on complete 
discharge. 
9 Fluid ounces of the new additive was prepared as shown in Example I. 1.5 
Fluid ounces of this solution was added to a new 12 volt 6 cell 
lead-sulfuric acid storage battery which had been fully charged (Battery 
A). This battery was placed in an automobile and discharged by leaving the 
lights on for 6.5 hours. At that time the battery was discharged and 
unable to start the automobile. The lights were turned off and the 
automobile allowed to stand idle for 2 hours. At that time attempt was 
made to start the automobile, and the battery responded immediately to 
start the car as if it was fully charged. 
EXAMPLE V 
This example illustrates the essential nature of the components of the new 
additives of the present invention. 
An additive was prepared without the use of the chelating agent by adding 
3.0 grams of ferrous sulfate heptahydrate, 7.0 grams of magnesium sulfate 
to 6.0 ounces of water and 35% sulfuric acid added to bring the total to 9 
fluid ounces. 1.5 fluid ounces of this mixture was added to the cells of a 
new 12 volt 6 cell lead-acid storage battery. The battery was then subject 
to charge and required over 5 hours to reach a full charge. The related 
battery in Example I containing the additive with the chelating agent was 
fully charged in only 2.5 hours.