The concept of being able to access a rechargeable source of power has existed for hundreds of years. In fact, some scientists believe that batteries have existed in one form or another since as far back as Egyptian times. However, it would not be until 1859 when the first lead acid battery was invented by Gaston Planté.[1]
While the batteries themselves have certainly advanced since these times, many of their core concepts remain the same. It should also be noted that although alternatives are now available, the traditional lead acid battery is still one of the most widely used sources of power on the markets today.
So, it is therefore important to address a few questions. How does a lead acid battery work? What are some of the primary features of this type of battery? Do these batteries offer any unique benefits? Are there any potential drawbacks? Those who are curious to learn more should find the information highlighted below quite interesting.
In order to appreciate the mechanics of a typical lead acid battery, it is first a good idea to discuss a bit of chemistry. This type of battery uses chemical reactions as a means to create electricity; specifically how lead and sulphuric acid interact with one another. Lead acid batteries can also be separated into a handful of core components including:[2]
All of these are then mounted into some type of container (normally made of plastic) in order to keep the toxic ingredients locked inside.
Fundamentally, a lead acid battery will begin to produce a charge when the sulphuric acid reacts with the exposed lead. This involves tiny sulphate ions bonding to the surfaces of the lead plates. The end result is the production of an electrical charge. This charge can then be stored within the battery or instead used as a readily available source of power.
As the process continues, the electrolytic solution will be depleted of sulphuric acid; resulting in a liquid comprised primarily of water. This ultimately leads to the lead acid battery losing its charge. It can be replenished by reversing the reaction so that the electrolyte once again becomes saturated with sulphuric acid.[3]
Now that we have taken a quick look at the basic principles of this type of battery, why is the term "lead-acid" often used? The simplest answer once again involves the ways in which electricity is produced. As power is generated by the interaction of lead with sulphuric acid, such a term is only logical to employ.
Note that the phrase "lead-acid" is also employed to differentiate a lead acid battery from other types of power supplies including:[4]
Let's also point out that a lead acid battery can actually be broken down into a handful of categories. This leads us into the next main section of the article.
Although the typical uses of a lead acid battery will be examined a bit later, it is still important to note that these uses can affect how the unit itself is configured. There are three primary variants of a lead acid battery and each of these has been engineered with a handful of specific characteristics. Each is described immediately below.
This first variety of lead battery is also the oldest as well as the most common. As the reader might have already guessed, these batteries are equipped with a series of valves that moderate the pressure contained within the vessel. The issue here is that valve-regulated batteries can produce dangerous gases under pressure. Such gases may also corrode specific elements if left unchecked.[5]
Therefore, built-in valves have been designed to recognise when the pressure becomes too high. Venting the accumulation of any gases helps to prevent the lead acid battery from leaking and in some cases, it may even prevent an explosion. The valves are located on the top cover of the battery and for this reason, the unit must be installed in an upright position. Perhaps the most common example of a valve regulated lead acid battery involves those which are used to power motor vehicles.
This next variant can also be referred to simply as a "gel" battery. A gelled electrolyte lead acid battery was first introduced to the public in the 1970s and 1980s. The main difference between this lead acid battery and the one mentioned in the previous section is that the electrolyte contained within this lead acid battery has been transformed into a gel through the use of a silica binder.[5]
Furthermore, any gases generated during the production of electricity (mainly hydrogen and oxygen) are automatically recombined. This type of lead acid battery therefore requires little maintenance. Gelled acid batteries were originally desirable due to higher levels of efficiency as well as improved safety features. However, certain downsides also exist. These include:[5]
So, it is clear to appreciate why manufacturers have begun to phase out this type of lead acid battery.
A final type of lead acid battery is technically referred to as an advanced glass mat valve-regulated sealed battery. However, we will refer to this configuration with the simpler acronym of AGM.
An AGM lead acid battery employs a host of innovative techniques in order to offer improved safety, efficiency, longevity, and durability. One example can be seen in the presence of a thin glass mat contained within the lead acid battery itself. This mat absorbs the nearby sulphuric acid while allowing gases to recombine. It also offers a greater surface area from which electricity can be generated.[6] In other words, it is able to produce power at a faster rate when compared to previous lead acid battery designs.
The presence of glass mats also prevents the electrolytic solution from sloshing back and forth; enhancing levels of safety. Another interesting benefit involves the fact that AGM materials are known for their low levels of electrical resistance.[6] This further increases their efficiency and reliability. Greater levels of efficiency have likewise led to lighter and smaller batteries (due to the fact that less electrolytic solution is required).
Regardless of the exact type of battery configuration, charging is still required. Let's now move on to discuss how the lead acid battery charging process takes place. Note that it is very important to recharge a lead acid battery between uses, as if the power level drops to zero, an entirely new replacement will be required.
Once again, the main intention of recharging a lead acid battery is to remove the accumulation of sulphur on the lead plates. This is normally accomplished through the use of an external DC power supply.[7] A separate power source (normally in the form of a store-bought recharging assembly will be required. The positive and negative terminals of this device will be placed upon the anode and cathode connections of the lead acid battery.
Note that the current applied will depend on what the lead acid battery is intended to be used for. For instance, 2.3 volts are normally recommended for slow charging while slightly higher power levels of 2.45 volts are preferred for fast charging a lead acid battery.[8] It is still important to read the instructions or to consult with the manufacturer. Incorrect amounts of electricity or miscalculated charging times can damage the lead acid battery and even increase the risks of a catastrophic failure.[9]
Although a lead acid battery represents a reliable source of power, even the most modern configurations will eventually become less efficient. Having said this, a properly sealed lead acid battery will enjoy an average lifespan of between three and five years. Some may even offer lifetimes as high as 12 years or more.[10] This depends on the exact type of battery as well as environmental conditions such as temperature and humidity.
There are three primary reasons why a lead acid battery may no longer be able to provide power:[11]
Sulfation is defined as a buildup of lead sulphide on both internal battery plates. This dramatically decreases the life of the lead acid battery and if left unchecked, it ultimately causes a failure. There are nonetheless times when recharging can help to remove this accumulation although such an attempt should only be made after consulting with the manufacturer.
There are also times when certain elements within a lead acid battery may become corroded over time due to the presence of sulphuric acid. These processes will eventually cause the lead plates to oxidise into a form of lead known as lead oxide. Plate corrosion will also damage the internal structures that are required to accumulate and distribute electricity. It is important to mention that even the most modern lead acid battery will still experience corrosion.
Finally, a depletion of electrolytic fluid within a lead acid battery can cause a failure. The gradual loss of electrolytes can partially be addressed by adding distilled water from time to time. Unfortunately, this fluid will still become depleted as a direct result of recharging.
The chemistry of a lead acid battery dictates that it is generally used to provide short bursts of power as opposed to long-term supplies.[12] This is why the majority of such batteries are often used within the automotive sector as a means to start a vehicle. However, there are other instances when a lead acid battery may provide the most effective solution.
For example, a lead acid battery may be used as a standby power supply within electrical substations, communications facilities, computer centres, alarms, and even off-grid housing.
There are also instances when a lead acid battery is preferred as a source of power within the e-mobility sector. Common examples include electric bicycles, hybrid vehicles, wheelchairs, and e-scooters.[13]
Having said this, the days of the typical lead acid battery may still be numbered due to a host of emerging technologies. Let us examine some modern alternatives to this type of power.
Lithium-ion batteries have become commonplace in recent times and they can often be used to replace a traditional lead acid battery. So, what are the differences between these two options? Is a lithium-ion battery better than a lead acid battery?
One major benefit of a lithium-ion battery involves a much longer life cycle when compared to a lead acid battery. This reduces costs associated with replacements as well as disposal.[14]
Furthermore, lithium-ion batteries are associated with efficiency rates as high as 95 per cent. A typical lead acid battery boasts rates of between 80 and 85 per cent.[14] This is another way of stating that lithium-ion batteries are capable of providing more robust supplies of on-demand power (partially due to the amount of energy an Li-ion battery can store at any given time).
It should still be noted that a lead acid battery will be priced significantly lower than a lithium-ion battery. However, the sheer longevity of a lithium-ion battery will normally serve to offset this observation.
One of the latest innovations within the lead acid battery marketplace comes in the form of what is known as an "UltraBattery". What is the difference between this new configuration and a standard lead acid battery?
UltraBatteries feature a hybrid design which is primarily defined by vastly increased capacitor storage capabilities. Discharge rates have likewise been improved; leading to impressive levels of efficiency. However, the main takeaway point here is that ultrabatteries are capable of maintaining a steady charge for longer periods of time (unlike the normal lead acid battery). Thus, they represent a reliable form of on-demand power (ideal for applications such as being placed as backups within remote energy grid infrastructure).[15]
While this type of fuel cell technology is still being developed, researchers believe that it might one day be capable of replacing traditional lead acid battery configurations (such as those used to supply power to the average automobile).
While it is impossible to deny that the standard lead acid battery offers some unique benefits, it is equally important to remember that this technology has existed for well over 100 years. There are nonetheless several downsides to a lead acid battery including:[16]
Of course, it only stands to reason that the internal components of a lead acid battery are highly toxic to the environment. This causes problems in terms of both long-term storage and disposal. The good news is that certain emerging technologies are capable of tackling the issues outlined above.
A hydrogen fuel cell offers several advantages when compared to a lead acid battery. One of the most important is associated with its environmental impact. As the only byproducts of hydrogen fuel cells are heat and water, they are much more ecologically friendly.
These cells are also lightweight and compact. This equates to lower transportation costs. Furthermore, the amount of time required to recharge such cells is much faster when compared to a lead acid battery.[17]
The use of hydrogen as a source of power has been appreciated for some time. However, implementation was somewhat of a problem in the past due to technical issues as well as the cost to the average consumer. As this innovative approach continues to evolve, there is no doubt that its presence will be felt across numerous sectors. It may one day even replace the lead acid battery industry.
DMFC technology uses methanol as a source of power. Once again, there are several advantages of such a technology when compared to the presence of a lead acid battery. Some unique observations include:[18]
Still, several challenges will need to be overcome in order to usher in this type of technology. Examples include developing more efficient membranes and lowering the amount of time required to achieve a desirable current.[19] This is once again why a significant amount of research is currently being carried out.
Does the lead acid battery industry have a future? Might the lead acid battery sector collapse in the coming years? These are interesting questions and while there is no doubt that alternative technologies are emerging, the lead acid battery marketplace is still massive on a global scale. Furthermore, advanced batteries are not likely to become available to the general public for a number of years. While the standard lead acid battery may be somewhat dated, the fact of the matter is that these sources of power should remain for some time.
Lead-acid batteries can be divided into:
The common applications of a lead acid battery are:
A major advantage of a lithium-ion battery is its much longer life compared to a lead-acid battery. In addition, lithium-ion batteries have efficiencies of up to 95 percent. A typical lead-acid battery has an efficiency between 80 and 85 percent. However, it should be noted that the price of a lead-acid battery is significantly lower than that of a lithium-ion battery.[14]
Sources
[1] https://www.sciencedirect.com/science/article/abs/pii/S0378775310000546#
[2] https://batteryaccessories.net/blogs/news/how-does-a-lead-acid-battery-work
[3] https://www.rbbattery.com/how-does-a-lead-acid-battery-work/
[4] https://www.des.nh.gov/sites/g/files/ehbemt341/files/documents/2020-01/hw-23.pdf
[5] https://batteryguys.com/pages/battery-types-and-comparison
[6] https://www.power-sonic.com/blog/the-complete-guide-to-agm-batteries
[7] https://batteryguy.com/kb/knowledge-base/can-i-recharge-a-completely-dead-sealed-lead-acid-battery/
[8] https://www.power-sonic.com/blog/how-to-charge-a-lead-acid-battery/
[9] https://www.centurybatteries.co.nz/content/documents/battery-talk/issue-3-battery-talk-exploding-batteries.pdf
[10] https://www.power-sonic.com/blog/features-of-sealed-lead-acid-batteries/
[11] https://sens-usa.com/wp-content/uploads/2015/09/3-Solutions-to-Leading-Causes-of-Battery-Failure-in-Gensets.pdf
[12] https://www.osti.gov/servlets/purl/1502636#:~:text=Lead%20acid%20batteries%20can%20be,%2C%20grid-%2Dscale%20power%20systems.
[13] https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery#Applications
[14] https://www.thepilotgroup.co.uk/lithium-ion-battery-vs-lead-acid-battery/
[15] https://www.mkbattery.com/blog/what-ultrabattery
[16] hhttps://www.powertechsystems.eu/home/tech-corner/lead-acid-battery-downsides/
[17] https://www.alicat.com/battery-vs-hydrogen-fuel-cell-vehicles/
[18] https://www.sciencedirect.com/topics/engineering/direct-methanol-fuel-cell
[19] https://www1.eere.energy.gov/vehiclesandfuels/pdfs/success/dmfuelcell3_23_01.pdf