AGM Vs. Lithium Batteries: Which Are Better For Solar RV And Camper Van Battery Banks?

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The lithium battery market for RVs and campers is expected to grow 64 percent faster than the overall RV battery market over the next five years, which indicates that lithium batteries will continue to outperform lead-acid batteries. Learn about the pros and cons of each type of battery before deciding whether lithium or lead-acid batteries are right for your solar battery bank, whether you are replacing solar batteries in your RV or camper van, building a new van, or upgrading to lithium.

Types of Lead Acid and Lithium Batteries

In addition to gel, flooded, and absorbent glass mat (AGM) batteries, there are various types of lead-acid batteries. It is the internal construction of the battery that differentiates AGM, gel, and flooded batteries, even though all of them contain lead-acid. To hold the electrolyte in place with capillary action, AGM batteries use a fiberglass separator between the wrappers and plate. Capillary action is similar to how water creeps up a towel in a bath when placed in it. As a result of this capillary action, the liquid is unlikely to spill when exposed to the AGM Battery. In this comparison, we will compare AGM batteries to lithium batteries since they are low maintenance and the newest type of lead-acid battery.

Several types of lithium batteries exist, ranging from Lithium Iron Phosphate (LFP or LiFePO4) to Lithium Nickel Manganese Cobalt Oxide (NMC), Lithium Cobalt Oxide (LCO), and Lithium Nickel Cobalt Aluminum Oxide (NCA), all of which can be classified as lithium batteries containing cobalt or not. Since LiFePO4 batteries are extremely stable, they do not pose a thermal runaway risk like lithium cobalt-based batteries. In LiFePO4 batteries, oxygen and phosphorus atoms are strongly linked by covalent bonding, which makes it possible for the ions to remain stable during charge cycles despite oxygen flux. It is possible for cobalt-based lithium batteries to overheat because of the weak cobalt-oxide bond, which can cause damage and shorten the battery’s lifespan. Due to their inherent safety, lack of thermal runaway risk, and longer average lifespan compared to lithium cobalt-based batteries, LFP batteries are a popular choice in RV and mobile applications.

Top 7 Factors to Consider When Comparing AGM to Lithium Batteries

You will need to take into account your potential battery bank’s size, weight, energy density, safety, and maintenance requirements before embarking on your next adventure if you want to be fully self-sufficient and worry-free. Due to the limited space in your vehicle for batteries, you will want to make sure you maximize your space while optimizing your gas mileage with a more lightweight system that maximizes your space. Especially as the battery bank will be close to you while you sleep and drive, you will need one that is safe and does not pose any health or safety risks. Additionally, taking into account the battery bank’s lifespan, charge time, depth of discharge and cost, will ensure you are getting the greatest bang for your buck long-term as well as making the most out of your limited solar power. See below for a comparison of AGM and LFP solar battery banks for RVs and campers.

1. Physical Size, Weight & Energy Density

Compared to AGM batteries, lithium batteries typically weigh less and are often smaller, which is one of their biggest advantages. Depending on the energy demands of your vehicle and the number of batteries in your bank, this weight can really add up. This can result in lower fuel efficiency and additional fuel costs. In addition to weighing down your vehicle and taking up precious space, heavy lead-acid batteries also do not store significant amounts of energy relative to their large size. As a result of this metric, lithium RV batteries have a much higher energy density than lead-acid batteries in terms of their weight and space. Therefore, lithium batteries can store up to four times as much energy as a lead-acid battery of the same size. Due to the limited space and weight of mobile use cases, this higher energy density is a huge benefit. By releasing space that would normally be taken up by larger lead-acid batteries, you are able to store more items.

2. Safety

Safety is an important consideration as you will be sleeping and living close to the battery bank. In order to prevent the build-up of hydrogen gas, which can poison the breathable air and damage your RV or van, as well as cause battery damage, or worse, explode, many lead-acid batteries, including AGM batteries, need to be in a well-ventilated compartment within your RV or van. It’s important to be aware of the dangers of hydrogen gas accumulation in your vehicle if you allow it to accumulate. Even a small spark can ignite the air and cause serious damage to your vehicle. Furthermore, all lithium batteries do not produce hazardous hydrogen gas when charged. Unlike lithium cobalt batteries, LFP batteries do not also pose a risk of thermal runaway. Because of this, LFP batteries can also be installed on their sides and in more space-restricted compartments.

3. Maintenance requirements

Despite the fact that AGM batteries are more maintenance-free than wet cell lead acid batteries, they still require venting since they are sealed. If your AGM batteries are monitored, your travels, self-sufficiency, and relaxation will necessarily be hindered. Additionally, AGM batteries pose the same risk of being overcharged as other lead acid batteries, which can cause long-term damage to the battery bank. You can build up a dangerous amount of hydrogen gas if you overcharge the AGM battery or charge it too quickly for the absorption mat to keep up. On the other hand, LFP batteries, such as those offered by RELiON, are the easiest and most maintenance-free batteries on the market to own, since they come with a well-designed and engineered internal battery management system (BMS) that protects the cells against overcharging or discharging automatically.

4. Lifespan

The upfront cost of lithium batteries is often higher than that of lead-acid batteries, but they have a much longer lifespan than lead-acid batteries. Therefore, the age-old adage holds true. On average, lithium batteries last 10 times longer than lead-acid batteries. The cycle life of lithium batteries, measured by how many times they can be discharged and then recharged before they need replacement, is 5,000 to 10,000 cycles. AGM batteries, on the other hand, might be capable of 400 to 1,000 cycles, depending on their quality, maintenance, and depth of discharge. With a lithium battery, you can expect it to last over 14 years if you cycle it once a day, whereas a standard lead-acid battery often lasts just two years. AGM batteries typically last longer than other lead-acid batteries, but their lifespan is still significantly shorter than that of all lithium batteries. When you live full-time in an RV and charge your batteries every single day, you will run out of lead-acid batteries much faster than lithium batteries. Depending on the depth of discharge and maintenance habits of your lead-acid batteries, you might even have to replace them every year. Last but not least, checking out the warranty of the battery you are considering can help you determine the battery’s minimum lifespan.

5. Efficiency and Charge Time

A lithium battery is more efficient than a lead-acid battery, so more solar power is stored and used instead of being lost during charging and discharging. An average lead-acid battery is 80 to 85 percent efficient, depending on its model and condition. When you have 1,000 watts of solar power coming into your batteries, you will only have 800 to 850 watts to use after charging and discharging them. In contrast, lithium batteries are over 95 percent efficient, so you would have over 950 watts of available power compared to just 800 to 850 watts in the case of lead-acid batteries.

The charging process of more efficient batteries is also faster, since they lose less energy. Because you will have more usable capacity on a daily basis with a solar battery bank that charges faster, you may have to purchase fewer solar panels and/or a smaller battery bank, depending on the configuration of your system. On average, lithium batteries charge four times faster than lead-acid batteries because they can handle higher charger amperages. However, AGM batteries still charge significantly slower than lithium batteries despite charging faster than wet cell lead-acid batteries. As a result, your vehicle and solar array may have to stay in a particular location for a long period of time for a full charge, resulting in a lower usable capacity per day.

In addition, you are able to start and stop charging the lithium batteries as necessary without impacting their performance or lifespan when it comes to charging. Due to these charge characteristics, it is not necessary to complete a long absorption cycle when charging AGM batteries partially. However, over time, AGM batteries lose their ability to charge to full capacity when partially charged. If you constantly charge your AGM battery to only 70 percent, for instance, the battery may eventually fail to charge beyond 70 percent. In turn, this reduces the battery’s lifespan, making lithium batteries more suitable for partial-charge applications, such as solar energy collection and regenerative braking.

6. Depth of Discharge

The depth of discharge (DOD), especially for lead acid batteries, is one of the more complex aspects of batteries. It determines how far you can drain the batteries before recharging them. If a lead acid battery is discharged below 50 percent DOD, its lifespan is significantly reduced, whereas lithium batteries can be discharged up to 100 percent without causing long-term damage. As a result, you will have far less usable capacity each day with AGM batteries if you can only discharge them to 50 percent full, so you’ll probably have to buy more AGM batteries to reach the same usable capacity as a single lithium battery.

7. Cost

Due to their long lifespan, efficiency, higher energy density, and ability to discharge deeply without damage, lithium batteries often require a higher upfront price point than lead-acid batteries. Lithium batteries are typically more cost-effective in the long run, especially when compared with AGM batteries that have shorter lifespans.

In addition, many people fail to take into account that lead-acid batteries are often much more expensive – sometimes double or triple as much – just to reach the same usable capacity as lithium batteries. Most people look at a battery’s total capacity (i.e., how many kilowatts it is theoretically capable of storing) rather than its usable capacity (i.e., how much kWh the battery can store after taking into account its depth of discharge, efficiency, and charge/discharge rates). There are fewer allowable depths of discharge, efficiency rates, and charge/discharge rates for lead-acid batteries, which directly impact the number of batteries required for a project. Over the course of a battery’s lifetime, the Levelized Cost of Storage or the overall cost per kWh that you will be able to get from it will also be significantly impacted.

The Bottom Line

Even though lithium batteries are more expensive upfront, they are better than AGM lead-acid batteries as solar battery banks for RVs and camper vans. In addition to being safer, especially in small spaces, LFP batteries are lighter, more compact, and energy-dense, and require less maintenance. Additionally, they outlast and outperform AGM batteries, saving you money on replacement costs down the road as well as maximizing the effectiveness of your solar array. AGM batteries can’t compete with LFP batteries when it comes to worry-free and self-sufficient adventures.

You can contact our team of experts to find out what will be the best fit for your lifestyle if you wish to upgrade to lithium batteries in your RV or camper van. For more information on how to find the right battery for your application and usage, email us at [email protected]

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