If you are looking for a reliable and economical method to store energy for your home or business, you may want to consider using lead-acid batteries. Lead-acid batteries, the world’s first rechargeable battery since 1859, have been powering vehicles such as cars, motorcycles, boats, and other vehicles. They are also commonly used in backup power systems, solar systems, and other applications requiring energy storage.
The working principle of lead-acid batteries involves a chemical reaction between lead plates and sulfuric acid electrolyte. Before understanding its working principle, we need to understand its structure. A typical lead-acid battery consists of three main parts: Lead plates: These plates are made of lead (Pb) and are responsible for the battery’s ability to store and release electrical energy. Electrolyte: The electrolyte in lead-acid batteries is a mixture of sulfuric acid (H₂SO₄) and water. This electrolyte undergoes chemical reactions that produce electrical energy. Separator: The separator is a porous material that prevents the positive and negative plates from touching each other while allowing ions to pass through.
Colloidal batteries: These utilize a gel to contain the liquid. They are highly suitable for devices such as solar systems because they are very stable in hot or cold weather and can better handle deep discharges. However, they are somewhat expensive, priced between $200 and $400. They require careful charging.
Deep cycle lead-acid batteries for solar systems: If you are on a tight budget, lead-acid batteries are an ideal choice for solar systems. Flooded lead-acid batteries are the cheapest type, suitable for off-grid solar systems. They do not require frequent deep discharges but have a short lifespan and low efficiency, and are sensitive to extreme temperatures, especially cold weather. AGM batteries are more convenient to maintain than flooded batteries, with an efficiency of about 90%. They are more expensive than flooded batteries but much cheaper than lithium batteries, making them particularly suitable for cold climates. GEL batteries are excellent for systems that require deep discharges. They can withstand more discharges without significantly affecting their lifespan. Although they are more expensive than flooded and AGM batteries, they have a longer lifespan and an efficiency of about 90%, making them most suitable for off-grid or grid-tied solar systems. Is lead-acid better than lithium for solar storage? The answer is no, lithium batteries outperform lead-acid batteries in the field of energy storage and are being widely applied in the solar sector. Lithium batteries have the following advantages: Cycle life: between 3,000 and 5,000 charge cycles. Lifespan: 10 to 15 years of use. Efficiency: charging/discharging efficiency of about 95%. Energy density: higher, 150–250 Wh/kg. Weight and size: lighter and more compact due to higher energy density. If you look at the lifespan, lithium-ion batteries typically have a longer lifespan—about 10 to 15 years—while lead-acid batteries only last for 3 to 5 years. This means lithium-ion batteries can undergo 3,000 to 5,000 charge cycles, while lead-acid batteries only last for 500 to 1,200 charge cycles before their performance declines. In terms of efficiency, lithium-ion batteries are much better—with an efficiency of up to 95%, meaning less energy is lost during charging and discharging. On the other hand, lead-acid batteries only have an efficiency of 80% to 85%. Another significant difference is energy density—lithium-ion batteries are more compact and lighter because they can store 150 to 250 Wh per kilogram, while lead-acid batteries store much less energy, approximately 30 to 50 Wh per kilogram.Are lead-acid batteries cheaper than lithium-ion batteries? Yes, lead-acid batteries are cheaper than deep-cycle lithium-ion batteries. Lead-acid batteries are more affordable. Taking a common 100Ah, 12V battery as an example, the price of a lead-acid battery is only 1/3 to 1/2 of that of a lithium-ion battery. For instance, the price of a lead-acid battery is about $100 to $300, while a lithium-ion battery of the same capacity is between $600 and $1000.
Common questions about lead-acid batteries. How do I know when to charge a lead-acid battery? You can use a voltmeter or a hydrometer respectively to measure the voltage or specific gravity of a lead-acid battery. These are indicators of the charging state of a lead-acid battery, that is, the percentage of available capacity of the lead-acid battery. The higher the charging state, the higher the voltage or specific gravity. The lower the charging state, the lower the voltage or specific gravity. You can use the following table to compare the charging state, voltage, and specific gravity of a lead-acid battery: Charging state (%) Voltage (V) Specific gravity 100 12.7 1.265 75 12.4 1.225 50 12.2 1.190 25 12.0 1.155 0 11.9 1.120 As a general rule, you should charge a lead-acid battery when the charging state is below 50%, the voltage is below 12.2 V, or the specific gravity is below 1.190. You should also avoid discharging a lead-acid battery to below 20%, a voltage below 11.9 V, or a specific gravity below 1.120, as this can damage the lead-acid battery and shorten its service life. How do I charge a lead-acid battery? You can use a charger designed specifically for lead-acid batteries. The charger should match the voltage and current specifications of your lead-acid battery. You should also use a smart charger that can adjust the charging voltage and current according to the charging state and temperature of the lead-acid battery. Smart chargers can use a three-stage charging algorithm (including bulk, absorption, and float stages) to optimize charging efficiency and extend battery life. Bulk stage: The charger provides a constant high current to the lead-acid battery until the voltage reaches a predetermined level (usually 14.4 V). This stage can restore about 80% of the capacity of the lead-acid battery. Absorption stage: The charger reduces the current and maintains the voltage at a constant level (usually 14.4 V) until the current drops to a predetermined level (usually 0.1 A). This stage restores the remaining 20% of the capacity of the lead-acid battery and equalizes the charge of each cell. Float stage: The charger reduces the voltage and maintains a low and constant current to the lead-acid battery, usually 13.6V and 0.05A. This stage keeps the lead-acid battery fully charged and compensates for self-discharge.How to store my lead acid battery? Store lead acid batteries in a cool and dry place, away from direct sunlight, rain, dust and fire sources. Disconnect the lead acid battery from the charger and load, and unplug the cables and connectors from the terminals.
Summary: Lead acid batteries are one of the oldest and most widely used rechargeable battery types in the world. They have the advantages of low cost, high capacity, long cycle life and wide compatibility. They are also easy to install, operate and maintain, and are safe and reliable. Although it is not particularly suitable for solar systems compared to lithium batteries, if your budget is not enough, lead acid batteries can also provide a reliable and cost-effective energy storage solution for your home or business. If you want to know more about solar energy storage products, you can take a look at our home energy storage series. We can provide you with free solar solutions and preferential quotations. Click here to contact us.