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

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

Efficiency:
One of the most significant advantages of Li-ion batteries is their higher efficiency than lead-acid batteries. Li-ion batteries can convert 95% of their stored energy into usable electricity, while lead-acid batteries are only about 80% efficient. This means that if you have a 1,000-watt solar array, you'll only be able to convert about 800-850 watts into stored energy using lead-acid batteries, while you'll be able to convert 900-950 watts into stored energy using lithium batteries (this doesn't account for power conversion losses). Li-ion batteries can deliver more power for the same amount of stored energy, making them a more energy-efficient option.

Charging lithium-ion batteries is generally easier because they are more of a "set it and forget it" chemistry. With lead-acid batteries, the plates will sulfite (a buildup of crystalline deposits on the lead plates) if not fully charged, so the charger will typically do a higher voltage "desulfite" or "equalization" charge every few weeks or so. In contrast, lithium-ion batteries can be set to a single voltage and left as is. There is no equalization, float, or absorption setup required. We do provide insight on how to get started with a proper setup if using a traditional lead-acid charger vs. a lithium-ion charger, but this will void any warranty, and we recommend using a lithium-ion charger that is appropriate for your battery.

Cycle Life:

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

Lithium batteries are especially tolerant of deeper discharge cycles. For example, the life of a typical lead-acid battery will be significantly shortened if the depth of discharge (DOD) is below 50%, which is approximately 12.0 volts. In contrast, a lithium battery can last for thousands of cycles, even when fully charged and discharged to 100% DOD. That being 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 the battery.

Weight and Size:
Lithium-ion batteries are also much 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 key factors. Additionally, this makes lithium-ion batteries a popular choice for electric vehicles, as they can deliver a lot of power while remaining relatively lightweight, which increases the overall efficiency of the system.

For example, our 12v 100Ah updated battery weighs less than 30 pounds. An equivalent 31-pack deep cycle lead-acid battery weighs 70 pounds (source). That's nearly 60% less weight! One Higher Wire updated LiFePO4 battery is equivalent to two 100Ah lead-acid batteries when the 50% DOD rule is taken into account. Our product is half the size of an equivalent lead-acid battery and 80% lighter.

Maintenance:
Li-ion batteries require little maintenance, whereas lead-acid batteries require regular maintenance to ensure proper operation. For example, lead-acid batteries require regular watering to keep them functioning properly. This can be time-consuming and add extra expense to the total cost of ownership. In contrast, lithium-ion batteries are maintenance-free, saving the user time and money.

Our batteries contain a sophisticated battery management system (BMS) that constantly monitors all headway- battery cells within the battery. The BMS balances these headway cells to keep the voltages close to each other and has built-in protection in case the battery gets too cold or too hot, or if the battery is overcharged or loaded. In fact, you can even short the battery terminals together (don't try this at home) and the BMS will quickly shut down to protect you and the battery. It will reset in about 30 seconds after the load/charge is depleted.

Cost: Li-ion batteries have a higher upfront cost compared to lead-acid batteries. However, given the 10x longer cycle life and no maintenance, the total cost of ownership per cycle is typically much lower. In addition, the falling cost of lithium-ion batteries