Lead acid vs Lithium ion Batteries: What is difference in the RVs
Every RV enthusiast knows that a quality engine and indoor battery are the keys to a successful travel experience, but not everyone understands the pros and cons of different battery types. Is there a big difference between the two main types of batteries (lead acid vs lithium ion)?
Does it matter which type of battery you choose to meet your power needs as an RVer? (Hint: you bet it will!)
What’s the big deal? Well, once you understand the difference between lead acid and lithium ion batteries(lead acid vs lithium ion), you will be able to choose a battery or battery pack that will meet your needs for years to come. This is a big deal, so let’s jump right in.
Lead acid vs Lithium ion batteries
Lead-acid batteries have been around since the mid-1800s and are the earliest rechargeable batteries in existence! For over 170 years, the technology behind lead-acid batteries has been mature and successful. But that also means it doesn’t take advantage of state-of-the-art technology. Let’s see how this might affect the RV.
Lead-acid batteries use chemical reactions to generate electricity. Each 12-volt battery contains six (6) batteries. Each cell contains a mixture of sulfuric acid and water (to varying degrees). Each battery has a positive terminal and a negative terminal. When the battery generates electricity, it is discharging. The chemical reaction causes the sulfuric acid to break down into water that is stored inside each cell to dilute the acid. So using electricity will deplete the acid.
When the battery is recharged, the process is reversed, and the charging of the battery re-establishes the acid molecules. This process is the storage of energy. (Remember – a battery doesn’t store electricity. It stores the chemical energy needed to generate electricity.)
Each of the six cells in a 12-volt lead-acid battery is about 2.1 volts when fully charged. Together, these six batteries provide a fully charged battery that provides approximately 12.6 volts. (We use terms like “about” and “around” because the exact voltage depends on various factors specific to the battery and the use and care of the battery.)
In most cases, lithium-ion battery technology is superior to lead-acid due to its reliability and efficiency, among other attributes. However, in cases of small off-grid storage systems that aren’t used regularly, less expensive lead-acid battery options can be preferable.
Lithium ion chemistries can accept a faster rate of current, charging quicker than batteries made with lead acid. This is critical for time-sensitive applications where vehicles have high utilization and fewer break intervals.
Can you replace the lead acid battery with lithium? Yes, you can replace your lead acid battery with a Lithium ion one. However, there are some things you need to know first before making the transition. You will not need an external charger to charge your Lithium ion battery.
Types of lead acid batteries
Now that we know how a typical lead-acid battery works, let’s take a look at the various types of lead-acid batteries available and the differences between them.
A flooded lead-acid battery is a type of battery typically used as an engine battery to start a vehicle. This type of battery can also be used as a golf cart or motorcycle battery, or even as a deep cycle battery in a solar system.
With submerged lead acid batteries, the owner has access to the aforementioned six (6) individual batteries, and can (and should!) add distilled water to the batteries to keep them from drying out. These batteries are heavy and require some serious maintenance.
Sealed lead-acid batteries are essentially the same as far as the internal functions of the battery itself are concerned. However, the word “sealed” means we can’t use six cells the way we can in a submerged lead-acid battery. These batteries are often used as engine start batteries or for deep cycle applications.
Unlike submerged lead-acid batteries, manufacturers make sealed lead-acid batteries with enough acid to last the battery for a foreseeable warranty period. People don’t add distilled water to sealed lead acid batteries, so no real maintenance is involved. These batteries also do not release gas and can be installed in enclosed spaces.
Absorbent Glass Mat (AGM)
AGM stands for “Absorbed Glass Mat,” which means the electrolyte in these batteries is suspended near the lead plate. This approach is said to improve the efficiency of discharge and charge rates. It is not uncommon to use AGM batteries in RV or marine applications or in engine batteries. While an AGM battery is different from submerged and sealed batteries, it is still a wet battery.
Like the AGM battery, the Gel cell battery has a suspended electrolyte, but the Gel cell contains silica, which makes it hard, so it is not a wet battery like an AGM battery.
Gel batteries are probably the most sensitive in terms of damage from overcharging. These batteries require special chargers and are often found in deep cycle applications such as wheelchairs, trolling motors, and RVs. Gel batteries are not as common as the other types of lead-acid batteries we’ve discussed.
Advantages of lead-acid batteries
Lead-acid batteries are popular for a variety of reasons. First, they offer mature technologies that have been around for over a century and a half. This often gives people a sense of security in a widely understood technology.
Lead-acid batteries are relatively cheap to produce (albeit bad for the environment), so buying them up front is relatively cheap. They initially seemed like a better deal for consumers given the cost. However, this doesn’t take into account the overall life of the battery or the actual energy you get from it. Read on to find out how lead acid compares to lithium in these areas.
Lead-acid batteries are capable of deep discharge, although deep discharge can significantly affect battery life.
Disadvantages of Lead Acid vs Lithium ion Batteries
While lead-acid batteries have been the most successful energy storage source for many years, they have some major drawbacks compared to modern lithium batteries.
Weight, space and energy density
Lead acid batteries are very heavy. Weight can be a serious downside to mobile apps. They also don’t store a lot of energy for their size. Their weight means that providing enough power for home use will take up a lot of space. How much they store per weight and space is called their energy density, which is relatively low as far as batteries go.
Charge and discharge requirements
Lead-acid batteries are taking a long time to charge. The long charging times are due to their internal design that causes charging to slow down as it nears completion. Absorbing charge cycles causes this slowdown.
If the battery does not absorb charge by absorbing it before discharging, it will cause the battery to sulfate. Sulfation affects charging time, charging efficiency, and increases battery temperature.
When you discharge a lead-acid battery for too long, it also loses some of its ability to accept a charge, reducing its capacity. This damage is because the lead sulfate crystallizes and no longer dissolves.
If there is a problem with any of the above charging parameters, the life of the lead-acid battery will be shortened. Even if all parameters remain perfect, a battery’s chemistry breaks down with use and reduces the battery’s capacity over time.
Impact on the environment
Lead-acid batteries are among the most recycled items in the world. This is great and critical because their lead content has caused significant environmental and health concerns over the years. However, 5% of lead-acid batteries are not recycled. As a result, millions of metric tons of lead are dumped into the environment.
Lead ore is also one of the most toxic minerals and contributes to a larger area of toxic groundwater. Long-term exposure to lead, even in trace amounts, can cause brain and kidney damage and learning problems in children, a concern for all of us who share this planet.
Lithium ion Battery
Lithium-ion batteries have grown in popularity in recent years, and for good reason. Let’s take a look at some of the reasons why these relatively new people are getting so much attention!
The chemistry of lithium-ion batteries during charging and discharging finds lithium ions moving between the positive and negative electrodes. When the battery discharges, lithium ions move toward the positive electrode, losing or gaining electrons in the resulting chemical reaction. These chemical reactions create a flow of electrons that produces an electrical current. The opposite happens during charging.
Mobile electronics such as cell phones, electric scooters and bicycles, hoverboards and wheelchairs typically use lithium batteries. But the use of lithium-ion batteries has expanded in recent years, and they have found a home in motorhomes, boats and a variety of solar applications.
Types of Lithium ion Batteries
Like lead-acid batteries, there are many different types of lithium-ion batteries. There are many more types of lithium-ion batteries, as their chemistries can vary widely. Despite the variety, most lithium-ion battery chemistries offer similar advantages over lead-acid batteries.
For the purposes of this article, we will mainly be referring to LiFePo4 batteries, the so-called Lithium Iron Phosphate batteries. “Lithium iron” is the most common chemical used in energy storage applications in RVs, boats and homes. People use these batteries because they offer superior performance over lead acid while being a very safe chemistry.
Advantages of Lithium ion Batteries
When comparing lead-acid vs. lithium-ion batteries, we have overcome almost all of the disadvantages of lead-acid. Especially in RV use, lithium-ion batteries will run multiple devices and appliances simultaneously. The RV’s inverter power capacity is the only limitation.
But if you have enough inverter capacity, you’ll find yourself running refrigerators, lights, fans, TVs, computers, and even air conditioners.
Weight, space and energy density
Energy density refers to how much energy a battery can store in the space and weight of each battery. Lithium batteries have a much higher energy density than lead acid batteries.
Higher energy density is a huge benefit for mobile use cases where space and weight are limited. For the same amount of lead-acid energy, a lithium battery weighs less than a quarter!
Fewer batteries are also required, so more space can be used for storage. Lithium-ion batteries store more energy in the same space and still save weight.
Charge and discharge characteristics
When evaluating lead-acid batteries versus lithium-ion batteries, we found that the voltage of lead-acid deep-cycle batteries dropped significantly under load and discharge.
Lithium-ion batteries have much smaller voltage dips and maintain higher voltages throughout their discharge cycles. Lithium batteries in the same RV application can provide all the peak power and higher voltages needed, no matter the load. The higher voltage makes them more suitable for running high-power applications like microwave ovens or stovetops.
One of the many advantages of lithium-ion batteries is that they can accept very high charge currents. This high charging rate means charging times are much faster than with any type of lead-acid battery. This higher charging rate does require a proper charger, but conceivably your battery will charge in a fraction of the time required for lead-acid batteries. That is an absolute victory!
Charging characteristics are hardly that important in Li-ion batteries. You can start and stop charging as needed without compromising battery performance or longevity. These charging characteristics mean there is no need to worry about long absorption cycles and make them more suitable for partial charging applications such as solar energy harvesting and vehicle regenerative braking.
Finally, lithium-ion batteries can withstand deep discharges better than lead-acid batteries. For example, if you regularly discharge a lead acid battery to around 50%, the battery will probably give you about 500-800 cycles before it needs to be replaced. By comparison, a lithium-ion battery discharged to even 20% is said to provide about 5,000 cycles. Therefore, the extended life of lithium-ion batteries is of great significance.
Disadvantages of Lithium ion Batteries
The main disadvantage of lithium-ion batteries that we usually hear about is cost. The upfront purchase cost of lithium-ion batteries is significantly higher than that of lead-acid batteries. If you accept that face value, your choice between lead-acid and lithium-ion batteries seems clear.
Before making a decision, however, it’s important to understand the extended lifespan and other positive factors that will ultimately make the cost of the two batteries more similar over time.
Perhaps the real disadvantage of Li-ion batteries compared to lead-acid batteries is that these batteries are distributed far less than lead-acid batteries.
For RV applications, for example, there are fewer suppliers selling LiFePO4 batteries than every auto store and hypermarket that sells lead-acid batteries. Luckily, once you buy lithium batteries, you don’t need to replace them like lead acid, they should last the life of your vehicle (or even longer!).
While lithium-ion batteries can accept very high charge currents, they need to be charged according to the manufacturer’s recommendations. This means you may need a new device to charge the battery properly.
If lithium-ion batteries are connected to conventional charging equipment, such as a car’s alternator, they can damage the charging equipment. Therefore, it is crucial to install the correct charger for your Li-ion battery.
Lead acid vs Lithium ion Batteries: Which is best
The question of which is best in lead acid vs lithium ion batteries depends largely on your application. For example, if you are in the market for a new battery to start your vehicle’s engine, then you will need to buy a lead acid battery.
However, if you’re an RVer looking to power multiple devices and/or appliances in your rig without worrying about how you use them or if they’re going to die, lithium-ion batteries may be the go-to.
For RV enthusiasts looking to power a variety of amenities while traveling, camping, or living full-time, lithium-ion batteries are a welcome addition to the energy storage space. Whether you want to stay comfortable and warm, keep food cold and safe, keep medicines effectively refrigerated, work or play on the road, lithium-ion batteries have joined the fray and they’re here to stay!