How long will 4 parallel 12v 100ah lithium batteries last​?

In the realm of portable power and off-grid energy solutions, lithium batteries have emerged as a frontrunner. The configuration of 4 parallel 12V 100Ah lithium batteries holds particular promise, but the burning question remains: how long will they last? In fact, the operating time of 4 parallel 12v 100ah lithium batteries depends on the load current. Assuming the connected load consumes 50 amps per hour, the operating time is 8 hours.

Understand the basics of lithium batteries

Each individual 12V 100Ah lithium battery is a powerhouse in its own right. The voltage rating of 12 volts determines the electrical pressure it can supply, suitable for a wide array of applications, from powering RV appliances to small-scale solar setups. The ampere-hour (Ah) rating, which is 100 in this case, signifies the amount of current the battery can deliver over an hour. When we wire 4 of these batteries in parallel, we're multiplying the available capacity while keeping the voltage constant at 12V. This parallel connection effectively gives us a cumulative capacity of 400Ah.

The Crucial Factor: Load Current

The longevity of these batteries hinges on the load current drawn. Imagine the battery as a reservoir of electrical energy, and the load current as the rate at which water is being drawn from that reservoir. For instance, if a device connected to these batteries draws a modest 10 amperes of current, we can calculate the runtime using the formula t=C_total/I,where C_total/I is the total capacity (400Ah) and I is the load current. In this example, t=C_total/I=40 hours. This means the batteries could power the 10A device continuously for 40 hours before being depleted.

However, not all applications have such a light draw. Consider a power-hungry tool that demands 40 amperes. Using the same formula, the runtime would be t=C_total/I=10 hours. It's evident that as the load current increases, the runtime decreases proportionally.

Real-World Applications and Considerations

In an RV scenario, where these batteries might power lights, a refrigerator, and a water pump, the load current varies throughout the day. The refrigerator compressor cycling on and off changes the draw, averaging perhaps around 20 - 30 amperes over time. In this case, the batteries could last between 13 to 20 hours, depending on the exact consumption pattern.

For a solar-powered shed used to charge power tools, if the tools draw 30A during intermittent use, the batteries would provide backup power for around 13 hours between solar charging sessions. But it's not just about the load current. Temperature also plays a role; extreme cold can reduce a lithium battery's capacity and performance, shortening the effective runtime.

Strategies to extend battery life

While discussing the battery life, we also want to know how to extend the battery life. I can also teach you some methods.
Control the number of charge and discharge times and charging speed: Frequent charge and discharge, overcharging will accelerate the attenuation of battery performance. Therefore, frequent charge and discharge should be avoided as much as possible during use, and appropriate charging methods and parameters should be selected.

Maintain a suitable ambient temperature: High temperature environment will accelerate the internal chemical reaction of lithium batteries, thereby shortening the battery life. Generally speaking, the suitable ambient temperature for lithium batteries is 20-25℃. Beyond this range, the attenuation rate of the battery will be significantly accelerated.

Balanced charge and discharge: When used in parallel, ensure that each battery cell can be charged and discharged evenly to avoid performance degradation due to differences between cells.

Storage and maintenance: Lithium batteries that are not used for a long time should be charged to 50%~80% of the power first, stored in a dry and cool environment, and charged once every period of time (such as 3 months) to prevent the battery from self-discharging and causing low power and irreversible capacity loss.

Conclusion

The lifespan of 4 parallel 12V 100Ah lithium batteries is a fluid concept, dictated by the demands placed upon them. Whether it's for emergency backup during a power outage, fueling adventures on the road, or enabling off-grid productivity, understanding the interplay between capacity and load current is key. By carefully assessing the power needs of our devices and factoring in environmental conditions, we can unlock the full potential of these energy storage marvels, ensuring they power our lives for as long as we need them to. Armed with this knowledge, we can make informed decisions about battery usage, maximizing their value and reliability in an ever-connected yet energy-dependent world.