Lead-acid and lithium-ion batteries are two types of rechargeable batteries installed in narrowboats but have distinctive differences in chemistries, performance, and applications.
Chemistry: Lead-acid batteries use a basic chemistry that has been around for over a century, while lithium-ion batteries are a newer technology that uses a variety of chemistries to achieve different performance characteristics. Lead-acid batteries e.g. wet cell, AGM, Gel, Lead Carbon, etc., typically use a combination of lead, lead oxide, and sulfuric acid to produce energy. In contrast, lithium-ion batteries use lithium cobalt oxide, lithium manganese oxide, or lithium iron phosphate in varying combinations. Lithium iron phosphate (“LiFePo4”) is the most common lithium-ion battery found onboard.
Performance: Lithium-ion batteries are known for their high energy densities, meaning they can hold more energy in a smaller, lighter battery, making them ideal for portable applications like smartphones and electric vehicles. They have a longer lifespan compared to lead-acid batteries, can be discharged more deeply, and can be recharged faster. Lithium-ion batteries are also less prone to self-discharge, meaning they retain their energy even when not used for an extended period. In comparison, lead-acid batteries are heavier and bulkier, have a shorter lifespan, and require longer recharge times. However, they are more cost-effective and are still commonly used in boats.
Applications: Lithium-ion batteries are commonly used in portable consumer electronic devices like smartphones, laptops, and handheld tools, as well as electric vehicles, solar and wind power systems, and medical equipment.
Overall, lithium-ion batteries generally offer excellent performance and are better suited for portable applications where weight, size, and quick recharging are important. In contrast, lead-acid batteries provide a cost-effective solution for applications where size and weight are not as critical, and where quick recharge times or high discharge rates are not required.
Installations: Careful design and planning are essential if lithium-ion batteries are to be installed. Charging and storage parameters are different to lead acid batteries and therefore it is unlikely that a simple ‘drop-in’ replacement will be possible. Higher charging currents, sensitivity to temperature, and charging methods are just three considerations.
Before installing lithium-ion batteries, advice from the battery manufacturer, a professional installer and your insurance company should be obtained to ensure all factors have been considered. You should not rely on a “mate in the pub” or anyone else without a professional duty of care to you.
The International Organization for Standardization (ISO) has produced a Technical Specification that provides relevant information – known as ISO/TS 23625:2021 “Small craft – Lithium-ion batteries”. It is currently going through the ratification stage to become an ISO standard.
If installed and operated correctly, lithium-ion batteries generally offer superior performance and are better suited for portable applications where weight, size, and quick recharging are essential. In contrast, lead-acid batteries provide a cost-effective solution for applications where size and weight are not as critical, and where quick recharge times or high discharge rates are not required.
If you rely on your boat’s engine or a generator for charging, lithium-ion batteries may offer benefits providing the battery charging and management systems are correctly configured. However, lithium-ion batteries do not respond well to continuous “float” charging or long-term discharge.
If your boat spends most of its time connected to a shoreline, lead-acid batteries may be more suitable.