Lithium-ion VS Lead-acid Battery Which is Better for My Solar System?

Lithium-ion VS Lead-acid Battery

Which is Better for My Solar System?

When you have thoughts about setting up a power backup system for your home, you can choose from several options available now in the market after narrowing down the specifications you needed. In this blog let's have a close examination of the two of the major selling battery types which are used in solar systems.

LEAD-ACID BATTERY BASICS

We’ve had lead-acid batteries in our markets for more than 100 years and it continues to be a force to reckoned with due to its established manufacturing base and relatively low cost. The two main types of lead-acid batteries are Flooded Lead-acid (FLA) batteries and Sealed Lead-acid (SLA)/Valve Regulated Lead-acid (VRLA) batteries.

FLA batteries have three requirements that SLA/VRLA ones don’t: they need to sit upright to prevent the electrolyte from leaking, a ventilated environment that allows gases to diffuse comfortably, and routine electrolyte maintenance. Moreover, the plates in FLA batteries are submerged in water.

SLA/VRLA batteries come in two forms: AGM (Absorbent Glass Mat) and Gel batteries, both of which share similar properties. Both of them require very little to no maintenance, and unlike FLA batteries, they are spill-proof.

One of the primary differences between AGM and Gel batteries is that the latter kind tends to have lower rates of charge and output capacity. They can’t manage as much current as AGM ones, which means they need longer recharge times and give out less power.

Lead-acid batteries come in “deep cycle” and “shallow cycle” styles. With SLA/VRLA “shallow cycles” batteries are used because they are able to deliver high power pulses over short periods. “Deep cycle” batteries have a lower rate of discharge and can operate for several hours.

LITHIUM-IRON BATTERY BASICS

The lithium-iron battery is a relatively new invention. In 1980, American physicist Prof. John invented a new kind of battery that utilized the migration of Li+ ion from one electrode to the other. By the ‘90s, the lithium-iron battery hit commercial markets.

As one of the lightest elements on the periodic table with some of the greatest electrochemical properties, lithium possesses the capacity to produce considerably higher voltages in relatively compact volumes. Lithium-iron cells are “deep cycle”. This means that are capable of being charged and discharged to much higher degrees than lead-acid batteries.

COMPARING LITHIUM-IRON BATTERIES AND LEAD-ACID BATTERIES

While lead-acid batteries have long dominated the market for their low cost and established manufacturing base, the soaring popularity of lithium-iron batteries over the last couple of decades has made it a strong contender. In fact, now lead-acid and lithium-iron are the two main kinds of batteries used for commercial and residential purposes.

Both lead-acid and lithium batteries are effective and wildly popular energy storage solutions. However, the two vary distinctly in terms of chemistry, cost and performance. Here’s how these two technologies stack up in different departments.

DEPTH OF DISCHARGE (DOD)

A battery’s depth of discharge is the measure of the percentage of energy that can be safely drained without causing any damage to it. To put it simply, it refers to the total battery capacity that can be safely consumed before it needs to be charged.

When it comes to lead-acid batteries, they can be safely discharged up to 50 percent. Continuing to use the battery beyond that point will negatively affect its lifespan and effectiveness. Lithium-iron batteries typically have higher depth of discharge values. 80 to 85 percent of the energy capacity can be drained before they need to be charged.

For solar power applications, the optimum lithium battery chemistry is lithium iron phosphate (LiFePO4). They don’t require the routine maintenance that FLA batteries need or a well-ventilated environment.

EFFICIENCY

A battery’s efficiency is one of the most important metrics to consider when making a purchase. The more efficient a battery is, the more energy it discharges with respect to how much it consumes.

For example, in the case of solar energy panels, lead-acid batteries have an efficiency rating of 80 to 85 percent. What this means is that for every 1000 watts of solar power absorbed by the batteries, only 800 to 850 watts are available for use. Compare this with lithium-iron batteries which have efficiency ratings of over 95 percent. For every 1000 watts, you’d have more than 950 watts of power available for use.

More efficient batteries also charge faster. With respect to the solar panel system you have set up, it may also mean you can use fewer solar panels, a relatively smaller backup generator, and lower battery capacity.

RATE OF CHARGE

What’s more is that higher efficiency ratings mean batteries can be charged at a faster rate than ones with lower efficiency. This is due to the fact that they are designed to handle more amperage from the charger. More amperage means more current. Considering lithium-iron batteries have higher efficiency ratings, they also have a faster rate of charge.

The rate of charge is expressed as a fraction that indicates the value in amp hours. For example, a battery with a 500 Ah rating receives 100 charging amps in five hours.

Because lead-acid batteries have a relatively limited amount of current that they can handle, it is common for them to overheat when they are charged with a higher amperage charger.

ENERGY DENSITY OR CAPACITY

A battery’s capacity or energy density is the measure of the amount of energy it can store (and, of course, discharge) within a given physical space. Capacity values for batteries tend to vary between manufacturers and models.

Generally speaking, lithium-iron battery systems tend to have higher energy density values than lead-acid batteries. This means that they can store a higher amount of energy for the same size. Standard lithium-iron batteries tend to be larger than lead-acid ones, however. And they are typically more difficult to install.

However, considering you may need several more lead-acid batteries to do the job that fewer lithium-iron setups can do, the trade off isn’t much. For example, to provide power to a 5.13 kW system you’ll need eight lead-acid batteries, but only two lithium-iron batteries to do the same job. Lithium-iron battery systems can also fit into smaller and tighter spaces if your energy requirements are high.

COST

When it comes to upfront and installation costs, lead-acid batteries are the more affordable option. Compared to a standard lithium-iron setup of the same size, a lead-acid battery system will typically cost you several hundreds—sometimes thousands—of dollars less. Costs depend on the size of the battery system and their installation needs.

However, while lead-acid batteries may ostensibly be more affordable, the long-lasting lifecycles and effectiveness of lithium-iron batteries offset those costs. Considering you won’t have to replace a lithium-iron battery as soon as you would have to replace a lead-acid one, they aren’t exactly more costly.

LIFESPAN

Of course, all batteries depreciate and lose effectiveness over time. The lifespan of batteries is measured by the number of charge cycles they can undergo. One charge cycle begins from the point at which you use it to when you charge it. The lifespan is the number of charge cycles the battery is capable of until it’s expected to expire.

Lead-acid batteries typically have widely ranging lifecycles—over 200 charge cycles in one year to 100 charge cycles in five years. Though findings vary from one study to another, lithium-iron batteries tend to last for several more charge cycles than lead-acid batteries.

SAFETY OF USE

Both lead-acid and lithium-iron batteries are generally safe to use indoors. They are specifically designed to provide a safer and more environmentally friendly alternative to power generators. However, no device or appliance comes without safety risks. Both types of batteries are capable to cell overheating leading to electrolyte and possible flame emission.

Considering lithium-iron batteries have higher energy densities, that is, they can store more energy in smaller volumes, they are more likely to undergo cell overheating. Most quality manufacturers take significant steps including built-in circuit breakers that kill the charging current when the voltage maxes out, if overheating occurs, or if excessive internal pressure builds up.

ENVIRONMENTAL IMPACT

When it comes to environmental friendliness, lead-acid batteries rank significantly lower than lithium-iron ones. This is due to the fact that they need much larger amounts of raw material for the same level of energy storage. This results in a far greater impact on the environment during the raw material mining process. What’s more is that the lead processing industry uses large amounts of energy, which in turn leads to higher levels of pollution. It’s important to note however, that while lead is an extremely hazardous chemical compound, the manufacturing process and packaging methods minimize the associated risks to human beings.

In the case of lithium-iron batteries, their carbon footprint is significantly lower, in spite of being sourced through mining. They are more environmentally friendly than lead-acid and nickel-cadmium options. Mercury, lead, and cadmium are highly toxic heavy metals that have been used in battery manufacturing for decades. Inefficient and improper disposal has resulted in considerable environmental damage over the years.

Lithium-iron batteries have a high potential for recoverability and recyclability, which makes them a worthy eco-friendly option.

PURPOSE: WHEN TO USE LEAD-ACID BATTERIES AND WHEN TO USE LITHIUM-IRON BATTERIES

If you need to install a battery backup system at home or at your store or workplace, both lead-acid and lithium-iron batteries are effective, efficient, and cost-effective alternatives to traditional gasoline power generators. Considering the many advantages—longer lifespan, greater efficiency, less environmental impact, greater safety of use, higher energy density, faster rates of charge, and more depth of discharge—of lithium-iron technology, it makes more sense to opt for it for your energy storage solution needs.

Lithium-iron batteries offer significant benefits to home and business owners alike. Despite being one of the newer battery technologies in this age-old market, lithium-iron has proved to hold its own when it comes to efficiency, energy storage capacity, performance, durability, resilience, and cost-effectiveness.

Basen 12V 100Ah LiFePO4 battery pack, weighting 26.45 lbs, only 1/3 of a 100Ah lead-acid battery, while usable energy is twice of a 100Ah lead-acid battery. It provides 5000+ deep cycles (a 10-year lifetime) & extends the battery lifespan by 8 times more than a lead-acid battery.