Comparing the benefits of Lithium-ion vs. Lead Acid batteries

Batteries are essential for powering many of our everyday devices, from smartphones to electric vehicles. However, not all batteries are created equal. Lithium-ion (Li-ion) batteries and lead-acid batteries are two of the most commonly used secondary (aka rechargeable) battery types, and each has its own set of advantages and disadvantages. In this article, we will explore the benefits of Li-ion batteries over lead-acid batteries, including efficiency, cycle life, cost, and more. We are going to focus on lithium iron phosphate, as this chemistry is most often use to replace lead acid.

Efficiency:

One of the most significant benefits of Li-ion batteries is their higher efficiency compared to lead-acid batteries. Li-ion batteries can convert up to 95% of their stored energy into usable power, while lead-acid batteries are only around 80% efficient. This means that if you have, say, a 1000-watt solar array, only about 800-850 watts would be turned into stored energy using lead acid, versus 900-950 for lithium (this doesn't take into account power conversion losses). Li-ion batteries can provide more power for the same amount of stored energy, making them a more energy-efficient option.

Charging lithium-ion is generally easier, since they are more of a "set it and forget it" chemistry. With lead acid, the plates suffer from sulfination (crystalline deposit build-up on the lead plates) if not charged fully, so chargers typically have a higher-voltage "de-sulfination" or "equalization" charge every few weeks or so. Lithium-ion, by contrast, can be set to a single voltage and left alone. There is no equalization, float or absorb that need to be set. We do offer insight into proper settings to start with if using a traditional lead-acid charger with lithium-ion, although this will void any warranty and we recommend a proper lithium-ion charger appropriate for your battery.

Cycle Life:

Another advantage of Li-ion batteries is their longer cycle life. A cycle refers to a complete charge and discharge of the battery. Li-ion batteries can typically withstand hundreds to thousands of cycles, depending on the specific battery chemistry and usage, while lead-acid batteries usually only last for a few hundred cycles. This longer cycle life makes Li-ion batteries a better investment over the long term, as they can last significantly longer than lead-acid batteries.

Lithium batteries are especially more tolerant to deeper discharge cycles. For example, the life of a typical lead acid battery will go down significantly if discharged below 50% depth-of-discharge (DOD), which is roughly 12.0 volts. In contrast, a lithium battery can last thousands of cycles, even when fully charged and discharged to 100% DOD. That said, we do recommend charging to 14.0 volts and discharging to 12.0 volts (~80% DOD), as this will greatly extend the life of your battery.

Weight and Size:

Li-ion batteries are also significantly lighter and smaller than lead-acid batteries. This makes them ideal for portable devices and applications, such as laptops and smartphones, where size and weight are critical factors. Additionally, this makes Li-ion batteries a popular choice for electric vehicles, as they can provide a lot of power while remaining relatively lightweight, improving the system's overall efficiency.

For example, our 12v 100Ah renewed battery weighs under 30 pounds. An equivalent Group 31 deep-cycle lead acid battery weighs 70 pounds (source). That's nearly 60% lower weight! And if you take into account the 50% DOD rule, one Higher Wire renewed LiFePO4 battery is equivalent to TWO 100Ah lead-acid batteries. Our products are half the volume and 80% less weight than the equivalent lead acid battery.

Maintenance:

Li-ion batteries require little to no maintenance, whereas lead-acid batteries need regular maintenance to ensure proper operation. For example, lead-acid batteries require periodic water refills to keep them running correctly. This can be time-consuming and adds additional expenses to the overall cost of ownership. In contrast, Li-ion batteries are maintenance-free, saving users both time and money.

Our batteries include a sophisticated battery management system (BMS) that continually monitors all of the cells within the battery. The BMS balances those cells to keep them within close voltage of one another, and has built-in protections in case it becomes too cold or too hot, or there is excessive charge or load on the battery. In fact, you can even short the battery terminals to one another (DO NOT TRY THIS AT HOME) and the BMS will quickly shut down to protect you and the battery. It will reset approximately 30 seconds after the load/charge is removed.

Cost:

Li-ion batteries are more expensive upfront compared to lead-acid batteries. However, when considering up to 10x longer cycle life and maintenance-free operation, the overall cost of ownership per cycle is typically far lower. Additionally, the declining cost of Li-ion battery production means that prices are gradually becoming more affordable.

Higher Wire has gone one step further. Our renewed batteries are less than half the cost of the leading LiFePO4 battery and even cost-competitive with lead acid. Our rigorous grading process ensures that the batteries last many more cycles than a typical lead acid battery. In fact, we voluntarily pulled some of our earliest fielded batteries to test their performance. They were almost all above 85% of the initial tested capacity, meaning they could have continued service for far longer. This is just one of the ways that we maximize the useful life of energy storage systems.

Environmental Impact:

Finally, Li-ion batteries are more environmentally friendly than lead-acid batteries. Lead-acid batteries contain toxic lead and other hazardous materials, making them difficult to dispose of safely. In contrast, our renewed batteries have up to 95% lower carbon emissions as compared to new lead acid. When paired with renewable energy, they hit their environmental break-even in mere weeks. Thus we're making a truly carbon-negative product.

Conclusion:

In conclusion, Li-ion batteries offer several advantages over lead-acid batteries, including higher efficiency, longer cycle life, lower maintenance, and being more environmentally friendly. While new Li-ion batteries are initially more expensive, Higher Wire Renewed batteries are price-competitive with lead acid and offer a better long-term investment due to their extended lifespan and maintenance-free operation. With the continued evolution of our patent-pending process to grade cells for their continued use, we are sure to see more and more devices and vehicles using this technology in the future.