Lead-acid batteries have long been the default battery choice when electrifying diesel- and gasoline-powered vehicles, equipment, and machinery. Unfortunately, their shortcomings have traditionally made them impractical for larger agricultural equipment. This shortcoming is one reason the industry has been slow to adopt widespread electrified vehicle and equipment options.
Continuous developments in lithium battery technology, however, are making agricultural electrification much more attainable. The advantages lithium batteries present compared to lead-acid batteries have resulted in substantial performance improvements across all categories.
Limitations of Lead-Acid Batteries
As useful as lead-acid batteries have been for over 150 years, they do come with their shortcomings. The Alternative Fuels Data Center outlines some of the main challenges lead-acid batteries present:
- Low specific energy
- Declining performance capabilities in cold temperatures
- Ongoing maintenance requirements
- Short battery lifespan when compared to other battery options
Fortunately, lithium batteries offer solutions to these problems.
Lithium vs. Lead-Acid Comparison: Key Differences
As lithium battery technology continues to evolve, the agricultural industry has growing opportunities to pursue electrification—first with smaller or specialty equipment and later with higher-powered and higher-voltage equipment and machinery. The industry stands to gain greater operational efficiency and lower costs as a result.
Below are some of the main advantages lithium batteries offer compared to their lead-acid counterparts.
Minimal Maintenance Requirements
One of the most commonly touted benefits of lithium batteries—and one of the most appealing—is that they require little to no maintenance.
Compared to lead-acid batteries, in particular, lithium batteries generally have far fewer maintenance requirements. While lead-acid batteries may need to have their water levels topped off, lithium batteries are sealed and don’t require any significant maintenance over their lifetimes—just routine charging.
A shorter maintenance checklist can serve as a relief for operators, particularly during more active periods, like planting and harvesting seasons.
Greater Longevity
Lithium batteries can be safely discharged to 10% capacity without serious performance hindrance. Lead-acid batteries, by comparison, can suffer from reduced performance and battery life once the charge level falls below 50%.
But what about when batteries aren’t in use? When a lead-acid battery needs to be stored, it will continuously lose energy, which is why battery tenders often become necessary. By comparison, lithium batteries lose far less energy and have a considerably longer shelf life, which will vary depending on the properties of the particular battery.
Lithium batteries are also less prone to degrading after repeated charging sessions.
Finally, while lithium batteries may cost more upfront, when it comes to overall battery lifespan, they can commonly last for 2,000 or more use cycles—which is double that of a conventional lead-acid battery.
More Power Density
Lithium batteries also outcompete lead-acid batteries when it comes to power density. In other words, lithium batteries can store more power than equivalent lead-acid options in the same or smaller space.
In fact, one analysis showed lithium batteries outperformed lead-acid batteries by 500%.
This is an important characteristic for batteries used in agricultural applications because as technological developments continue, equipment with greater power needs can use higher-capacity batteries that are physically smaller and lighter.
That could allow more space for on-board chargers or other features. And lighter vehicle loads can provide additional benefits, such as increased efficiency and reduced soil compression.
Greater Power Output
Of course, the ability to deliver power is just as important as the ability to store it. Lithium batteries provide improved performance here, too.
Electrically powered equipment, machinery, and vehicles deliver torque instantly at low revolutions per minute (RPMs). On the other hand, internal combustion engines require time to build up to their peak torque potential.
The ability to deliver greater power output at lower operating speeds is an ideal quality for heavy-duty farm machinery, making lithium batteries an increasingly promising option to consider as the technology advances.
Fast-Charging Capabilities
One particular challenge that has delayed electrification in the agricultural industry is that charging times for lead-acid batteries are long. Not all farmers will have the luxury of waiting for their equipment to be ready.
During a harvest season, for example, farmers often contend with narrow windows of time when crops are both ready for harvesting and weather conditions allow for equipment to enter fields. For electric equipment and machinery to become a more practical option, their charging capabilities need to be able to keep up with a workflow that can be highly variable and located far from charging sources.
Lithium batteries significantly contribute toward eliminating this drawback, but larger agricultural equipment may require further advancement before those applications become feasible.
If you have familiarity with electric vehicles (EVs), you may already be aware that those on roadways today can be charged at different speeds based on various charging levels:
- Level 1 – Uses a standard 120V household outlet and makes use of alternating current (AC)
- Level 2 – Uses a 240V residential or 208V commercial outlet, makes use of AC
- Level 3 – Also referred to as direct-current fast charging (DCFC), greater power output enables significantly faster charging. Using EVs as the closest comparison, DCFC charges as much as 80% of battery capacity in 20 minutes to one hour.
Of course, charging options can become more complicated for larger vehicles with greater power requirements. The United States’ National Renewable Energy Laboratory (NREL) is currently working with other national labs to develop fast-charging options for heavy-duty vehicles like semi-trucks (e.g., under 30 minutes). Similar solutions would also address the charging needs of larger agricultural equipment.
With the proper battery management setup, fast-charging capabilities for agricultural vehicles and other equipment would allow farmers to avoid delays and keep operations running smoothly through busy seasons. Charging sessions could take place during breaks or overnight.
Alternatively, on-board charging equipment could be installed to extend the operating time and be connected to portable power sources as needed. Plenty of solutions are currently being explored.
Greater Durability
Agricultural equipment is exposed to various environmental conditions, and passing over rough terrain means that any battery used needs to withstand frequent movement and powerful vibrations. Lithium batteries already provide greater resilience against these factors because of their construction and sealed design.
Fortunately, ongoing developments are making lithium batteries even more durable.
Ongoing Lithium Battery Developments
As with any new technology, developments regarding lithium batteries are ongoing. Here are just a couple of recent examples.
Lithium-Oxygen Battery Advancements
A paper published earlier this year identified a molecular quenching/mediating mechanism that could help lithium-oxygen batteries perform more efficiently and open the door for more high-performance usage options.
Recycling Opportunities
While electrified equipment could help reduce the agricultural industry’s carbon emissions, one challenge that experts are still aiming to address is what to do with batteries once they reach the ends of their life cycles.
However, one recent study suggested that a sizable portion of the existing demand for many of its elements, including lithium, cobalt, and nickel, could be supplied by creating a closed-loop recycling chain with retired lithium batteries. Recycled content standards (RCSs) have already been proposed in the European Union, and the same could prove beneficial in the United States and elsewhere.
With as many advantages over lead-acid batteries as lithium batteries have, and with so many more developments underway, the possibility of electrifying agricultural equipment has never been in such close reach.
Agricultural machinery and equipment manufacturers have already begun seizing these opportunities for small- to medium-sized equipment, and this usage will only expand in the coming years.
