Lead-acid batteries have been around for more than a century now, and are the most common battery technology applied in solar, marine, power backup systems, vehicles, Uninterrupted Power Supply (UPS), and other common battery applications.
Over the past few years, lithium-ion batteries have been steadily gaining ground as the best battery for most solar, UPS, and backup applications.
Lithium-ion batteries have been long used in electronics like mobile phones and laptops. Advancements in the technology, coupled with the unique set of features and advantages that lithium offers have widened its use to become a major choice for solar and backup uses.
While both technologies are available in the market, knowing the details of the differences between the two technologies will inform the decision on what type of batteries to buy for your use.
This article will do a side-by-side comparison as well as a comprehensive analysis of the key differences between Lithium and Lead-acid batteries.
Lead Acid and Lithium-Ion Batteries: Side by Side comparison
The table below shows a quick comparison between Lead-acid and Lithium-ion batteries:
| Comparison Element | Lead Acid Batteries | Lithium Batteries | |
| 1 | Efficiency | – 80% efficiency. – Less power is available for use for your system. – More batteries are needed to achieve the same desired power. | – 95% efficiency – More power available for use – Fewer batteries are needed because of minimal losses. |
| 2 | Life cycle of the battery | – Shorter cycle life of between 400 to 1,200. – An average lifetime of 3 – 4 years | – Higher life cycles of between 5,000 – 10,000 cycles. – A lifetime of 10 years |
| 3 | Depth of Discharge | – 50% Depth of Discharge – Discharging more than 50% spoils the battery cells resulting in an even shorter lifespan for the battery. – More batteries are required leading to more costs. | – 90% Depth of Discharge – Almost all of the energy stored in Lithium-ion batteries can be used. -Fewer batteries are required leading to less costs. |
| 4 | Battery Charging Rate | – Longer charging rates of between 6 – 8 hours – The long charging rate is a major disadvantage for solar applications. – Lead-acid batteries are usually not fully charged even after many hours of charging. | – Faster charging rate of between 2 – 3 hours to charge to full capacity. – Double Advantage of higher depth of discharge and fast charging times. |
| 5 | Energy Density | – Lower energy density – A nominal voltage of 2v per cell requiring 6 cells to achieve 12V – More battery space is needed to achieve the desired capacity. | – High energy density, More energy is stored in a smaller battery size. – A nominal voltage of 3.2volts per cell requiring 4 cells to achieve 12.8V. – Less space is needed to achieve the desired capacity. |
| 6 | Weight & Size of battery | – Heavy and larger in physical size. – A 200Ah lead-acid battery weighs about 60kg. | – Light in weight and compact in size. – A 200Ah lithium-ion battery weighs about 30kgs. |
| 7 | Price | – Less costly – Lead acid prices in Kenya is between $300 and $500 (KSh. 30,000 – KSh. 60,000 ) | – More costly – Generally, lithium ion solar battery price in Kenya is between $800 and $3,000 (KSh. 140,000 – KSh. 350,000) |
From the table, you can see that Lead-acid and Lithium-ion batteries are quite different both physically and utility-wise.
Now let’s look at these differences in detail before selecting the best battery technology for your specific application.
Differences Between Lead Acid And Lithium-Ion Batteries
The key differences between Lead Acid and Lithium-Ion Batteries are:
1. Efficiency
Battery efficiency refers to the amount of output you can get from the battery out of the entire storage capacity of the battery.
Lead Acid Batteries have a typical efficiency of 80%, for good premium brands. Non-premium brands have even much lower efficiency levels of below 50%.
This means that you have less power available for use for your system. For illustration, for a 1000 watt-hours battery system, you get 800-watt hours of available power for use, with the other power lost due to the inefficiencies.
Lower efficiency means that you have to use more batteries to achieve the same desired power output.
Lithium-ion Batteries have higher efficiency of about 95%, on average for all brands and designs.
This means that you have more power available for use after charging the batteries. For example, from a 1000 watt-hours battery system, you get 950-watt hours of power available for use.
With the more efficient Lithium-ion Batteries, you will use fewer batteries because of higher efficiency from minimal losses.
2. Battery Life Cycle
The Life cycle of a battery refers to the number of times charging and discharging cycles can be performed on the battery. The life of a battery is measured by these cycles over its lifetime.
Lead Acid Batteries have shorter life cycles of between 400 to 1,200. This translates to an average lifetime of 2 – 4 years before they need replacement.
The battery life cycle depends on the specific use of the battery, the time for charge & discharge, and how much the battery is used (depth of discharge).
Lithium-ion Batteries have higher life cycles typically between 5,000 – 10,000 cycles. This translates to an average of 10 years of useful service life.
This means that Lithium-ion batteries have a longer lifespan than lead-acid batteries. Considering that lithium batteries can be discharged up to 90%, the life cycle is a significant advantage for the user.
3. Depth of Discharge
Battery Depth of Discharge refers to the capacity of the battery that can be safely used before recharging, without spoiling the battery.
Lead Acid Batteries can only be discharged/used up to only 50% of the capacity. For example, if you have a battery capacity of say 1,000 units (measured in Ah), you can only use 500 Ah.
Discharging more than 50% of Lead Acid Batteries deteriorates the battery cells resulting in an even shorter lifespan for the battery. A 50% Depth of Discharge means that you require more batteries in your system, leading to more expenses.
Lithium-ion Batteries can be discharged/used up to 90%. For instance, a battery with a capacity of 1,000 units (measured in Ah), can be discharged up to 900 Ah
This means that you get more from your lithium-ion battery by using almost all of the energy stored in the battery.
It also means that you can use fewer lithium-ion batteries are requires for the same application because you can get more energy from the battery you are using.
4. Battery Charging Rate
The battery charging rate refers to the speed at which the batteries can be charged to full capacity.
Lead Acid Batteries have a longer charging rate of between 6 – 8 hours.
For applications where solar is the primary source of power, the long charge times are a major disadvantage. Consider the varying sun levels during the day and the disadvantage compounds.
It is a common occurrence that batteries are not fully charged even after many hours of charging, and therefore not provide sufficient power when needed.
Lithium-ion Batteries have fast charging rates taking between 2 – 3 hours to charge to full capacity.
This means that you can fully charge the battery, use up almost all of it (up to 90%), and charge it again to full capacity well before the lead-acid battery ever gets full.
The high depth of discharge and fast charging rates are the key characteristics that set lithium-ion batteries apart from lead-acid batteries.
5. Energy Density
Energy Density refers to the amount of energy a battery can carry relative to the physical size of the battery.
Lead-acid batteries have a low energy density, meaning that less energy can be stored by the battery relative to its size.
Lead-acid batteries have a nominal voltage of 2v per cell. To get 12V, 6 cells will be required.
A low energy density means that you will need more batteries to achieve the desired capacity. This is not only expensive but will also require more space and related installation accessories, driving up the cost of the system.
Lithium-ion batteries have a high energy density, meaning that more energy will be stored for smaller battery sizes.
Lithium-ion batteries have a nominal voltage of 3.2volts per cell, meaning that 4 cells will deliver 12.8V. Consider this for 24V or 48V systems and the difference in size is significant.
With Lithium-ion, you need less battery space and related accessories to achieve the desired capacity.
6. Weight & Size of battery
Lead-acid batteries are usually heavy and physically larger compared to lithium-ion equivalents. A standard 200Ah deep-cycle lead-acid battery weighs 60kg.
Lithium-ion batteries are light in weight and compact in size compared to lead-acid equivalents. A 200Ah lithium battery will weigh about 30kgs.
7. Lithium ion solar battery price in Kenya
Compared to lead acid batteries, lithium ion solar battery price in Kenya is between $1200 and $3,000 (KSh. 140,000 – KSh. 350,000), depending on the capacity of the battery. A 200Ah, 24V Lithium-ion battery costs around $1,500 (KSh. 175,000).
Lead-acid batteries are currently less costly than Lithium-ion. The cost of a 200Ah 12V lead-acid battery is between $300 and $400 (KSh. 30,000 – KSh. 35,000in Kenya). The exact price will depend on the specific brand in the market.
Lead-acid Batteries – Most suitable Applications
Lead-acid batteries are robust and will serve most of the backup power needs, especially where the batteries are not used regularly or drained deeply.
In such cases, the batteries will serve well, and considering the lower cost will deliver value for money.
Also, in places where the grid is available and stable, a backup system based on lead-acid will be the best solution.
The choice of which battery to use will ultimately be determined by the application at hand, available budget, and the total cost of ownership for your system over its lifetime.
Lithium-ion batteries – Most Suitable Applications
Lithium-ion batteries are the perfect choice for residential setups that use solar as the primary source of power for everyday use.
Lithium-ion batteries store enough charge and they charge fast with the available sun.
Since Lithium batteries have a high depth of discharge, it means that you can use more energy from the battery without worrying about draining the battery.
Lithium Iron batteries will last longer and won’t need frequent replacement as is the case with lead-acid batteries.
Over the long haul, it delivers the best value for your investment.
How to Select the Best Lithium-ion Batteries
The main factors to consider when selecting Lithium-ion batteries are the desired voltages, application, and brand.
There are few brands that are high quality and reputable, including Victron Lithium batteries, Acceleron, and BYD among others.
Be keen to look for brands that have a proven track record of delivering safe and reliable lithium batteries.
Conclusion
Both lead-acid and lithium batteries have their strong points and their downsides.
However, Lithium-ion batteries have distinct advantages that are appealing for different applications over Lead-acid batteries.
At SupportKe, we have the expertise and experience of working with different battery types and systems. Contact us to help you design the best battery solution for your solar needs whether for home or business.
You can reach us Toll-Free on Phone no. 0800 211 245
or email us via help@support.ke