AGM vs. lithium batteries: Which one is better for RV and ship applications?

In today's modern era, portable power is essential for various applications, so selecting the right battery technology is crucial to achieve peak performance, longevity and cost-effectiveness.

AGM (Absorbent Glass Mat) batteries and lithium batteries are excellent options, both valued for their different properties and applications. Distinguishing between these battery types is essential for making informed decisions.

What is AGM battery?

AGM, the abbreviation for Absorbent Glass Mat, is a further developed form of lead battery. In contrast to conventional lead batteries, AGM batteries have the electrolyte (sulfuric acid) embedded in a fiberglass mat, making them leak-proof and maintenance-free.

AGM batteries are widely used in applications requiring reliable, maintenance-free power storage, including emergency power systems, renewable energy storage, marine and RV applications, and select automotive applications. Known for their ability to deliver high currents when needed, AGM batteries are ideal for situations where a reliable power source is of utmost importance.

What is lithium battery?

Lithium battery is a rechargeable energy source that uses lithium as an active material, making it very popular in a variety of applications. Lithium batteries are known for their high energy density, low self-discharge rates, and long lifespan and can be recharged hundreds to thousands of times. They are available in various chemical compositions, including lithium ion (Li-ion), lithium polymer (LiPo) and lithium iron phosphate (LiFePO4), each with different properties.

Lithium-ion batteries are widely used in consumer electronics such as smartphones, laptops and tablets, as well as in electric vehicles, power tools and energy storage systems. Their lightweight design and superior energy density make them ideal for portable electronic devices and electric vehicles.

Lithium batteries are valued for their ability to deliver significant power and high energy density, making them the preferred choice in many modern applications. However, proper handling and charging are essential to ensure safety and maximize their lifespan.

The comprehensive comparison of AGM and lithium batteries

To understand the performance differences between AGM and lithium batteries, we will evaluate them based on critical parameters. This analysis shows which battery is best in which category, allowing you to make an informed decision tailored to your specific needs.

Depth of discharge (DoD):

• AGM: Generally allows a depth of discharge of around 50%. If this limit is exceeded, the battery may be damaged and its lifespan shortened.
• Lithium: Supports much deeper discharges, often over 80% and up to 100% without adverse effects. Therefore, a lithium battery with the same capacity can provide up to twice as much usable energy compared to an AGM battery.

Lifespan:

• AGM: AGM batteries typically have a lifespan of around 300 to 500 cycles, which equates to around 3 to 5 years of use.
• Lithium: Lithium batteries generally offer a much longer lifespan, with cycle counts ranging from 4,000 to 15,000 cycles. For example, Timeusb lithium batteries can last between 10 and 15 years.

Size and weight:

• AGM: AGM batteries are usually heavy, a 12V 100Ah model weighs between 29 and 31 kg.
• Lithium: Lithium batteries, on the other hand, are significantly lighter and more compact. Timeusb 12V 100Ah Mini Group24 lithium battery, for example, weighs only 9.5 kg.

Energy density:

• AGM: An AGM Group24 battery typically has an energy density of around 7.23 Wh/lb.
• Lithium: In contrast, a Group24 lithium battery has a significantly higher energy density of around 60.95 Wh/lb.

Loading time and efficiency:

• AGM: AGM batteries typically have longer charging times and lower charging efficiency compared to lithium batteries. It typically takes about 8 hours to fully charge an AGM battery.
• Lithium: In contrast, lithium batteries charge faster and more efficiently than AGM batteries. Most lithium batteries support 0.2C charging; for example, a 12V 100Ah lithium battery can be fully charged in 5-6 hours with a recommended charging current of 20A.

Eco-friendly:

Both AGM and lithium batteries are recyclable and represent environmentally friendly options. However, lithium batteries have a slight advantage due to their higher energy density and longer lifespan, meaning fewer batteries need to be recycled over time.

Security:

• AGM: AGM batteries are generally safe, but can release hydrogen gas if overcharged or improperly maintained.
• Lithium: Lithium-ion batteries do not produce gas buildup and do not contain toxic liquids, making them inherently safe to use without additional safety precautions. Additionally, lithium batteries are equipped with a Battery Management System (BMS) for enhanced protection.

Bluetooth technology

Lithium batteries offer a clear technological advantage over AGM batteries. For example, Bluetooth technology enables convenient real-time monitoring of battery status, ensuring smooth operation before boat trips, RV adventures or UTV excursions.

Bluetooth connectivity allows users to easily monitor important details such as remaining charge, voltage levels and temperature. The app on your smartphone provides easy access to comprehensive battery data with just a few taps, eliminating guesswork and uncertainty and eliminating the need to worry about managing power needs.

Acquisition costs

Cost plays a crucial role when choosing between two battery types, focusing on two critical factors: acquisition cost and cost per kWh.

Lithium-ion batteries require a higher initial investment. Despite their superior performance in many respects compared to AGM batteries, the initial cost is significantly higher.

AGM batteries appear to be the more economical choice in terms of initial investment. However, when assessing lifetime costs, lithium-ion batteries demonstrate their superiority due to their significantly longer service life.

Aspect	AGM battery	Lithium battery
Discharge depth	Typically around 50%	Over 80%, up to 100% without damage
Lifespan	300-500 cycles, 3-5 years	4000-15000 cycles, 10-15 years
Size and weight	Heavier, 12V 100Ah: 63-70 pounds	Lighter, 12V 100Ah: 21 pounds
Energy density	7.23Wh/lb	6 times as powerful as comparable lead batteries
Recharge time	Longer loading times	Shorter loading times
Charging efficiency	Lower charging efficiency	Higher charging efficiency
Maintenance	Minimal maintenance, occasional equalization charging	Minimal maintenance, no regular equalization charges
Environmental pollution	Recyclable, less environmentally friendly due to energy density and shorter lifespan	Recyclable, more environmentally friendly due to energy density and longer service life
Security	Generally safe, possible release of hydrogen gas if overcharged	Safer, no gas release, equipped with BMS for protection
Bluetooth	None	Yes
Acquisition costs	Lower	Higher

Comparison of AGM and lithium battery applications

After evaluating the performance of AGM and lithium batteries based on various parameters, it is important to assess their suitability for specific applications.

Not all batteries are universal, and certain models may be excellent in certain scenarios. Let's look at the specific applications for which AGM and lithium batteries are ideal:

Leisure batteries

When choosing recreational batteries for RV or caravan, LFP batteries are highly recommended. In the RV battery market, consumers value factors such as long life, safety and minimal maintenance. Lithium leisure batteries, especially those with lithium iron phosphate (LFP) technology, meet these criteria excellently. For RVs with integrated lithium batteries, dedicated battery chargers are preferable to built-in chargers to ensure optimal performance.

Marine Batteries

Traditional liquid or gel batteries are not ideal for use at sea due to their sensitivity to motion, which can reduce their effectiveness. In contrast, most lithium batteries are solid-state and do not contain liquids, making them very suitable for use at sea.In addition, modern lithium batteries for use at sea such as the Timeusb Trolling Motor Battery series (12V 140Ah LiFePO4 battery) are equipped with improved battery management systems (BMS) that have been specially developed for use at sea. These systems increase reliability by providing resistance to moisture, dust, water and salt spray, ensuring long life in humid and difficult conditions.

Freezing conditions

Using batteries in freezing conditions presents challenges, particularly when charging, which can be difficult at low temperatures. AGM batteries are superior to lithium batteries in this respect.

However, advanced lithium batteries such as the Timeusb LFP batteries lithium have a self-heating function. This ability allows them to function similarly to AGM batteries even at sub-zero temperatures.

Solar energy storage

Lithium iron phosphate batteries are ideal for solar energy storage due to their high energy density, deep discharge capability and extended warranty. A single AGM battery may have a lower initial cost, but can deliver the performance of 16 AGM batteries over its lifetime. Therefore, LFP batteries are a better choice for solar storage applications.

UPS battery

Similar to the RV battery market, the uninterruptible power supply (UPS) market also favors LFP (lithium iron phosphate) batteries. They offer greater safety, require minimal maintenance and offer higher capacity compared to equivalent AGM batteries, making them a more convenient long-term choice to own.

The final decision

When comparing lithium and AGM batteries, both have unique advantages and disadvantages. However, if you prefer a reliable, efficient and lightweight, maintenance-free solution, the optimal choice becomes clear. Lithium batteries prove to be the best option for your application. Their improved performance, longer lifespan and integrated Bluetooth technology provide significant comfort and convenience. Additionally, it can ultimately save you valuable time and money.