Understanding your deep-cycle battery’s lifespan is crucial, whether it’s old or new. Various factors influence its life cycle, but let’s first define what a battery life cycle is and how to calculate it.
What Is A Battery Life Cycle?
As a battery is used and recharged, it gradually loses its original capacity. Its life cycle refers to the number of charge and discharge cycles it can complete before performance declines.
How To Calculate Battery Life Cycle?
After the first use, a battery may not recharge to full capacity, but this doesn’t indicate its end of life.
Commonly, manufacturers will provide data on acceptable performance and capacity reduction before a battery’s life cycle ends.
While there’s no standard, a general rule is that a battery’s life cycle is measured by the number of cycles it can undergo before recharging to less than 80% of its original capacity.
How Is The Depth Of Discharge Determined?
Battery capacity can also be understood through depth of discharge (DoD), which measures the percentage of battery capacity used relative to its total.
For instance, a new 100 Ah battery discharged for 20 minutes at a current of 50 A has a 16.7 % (50*20/60/100) DoD for that cycle.
As mentioned earlier, the life cycle limit is reached if the battery can’t be charged beyond 80 Ah, resulting in a starting 20% DoD even at “full” charge.
You can use a monitor like the Victron BMV-700 to track DoD accurately.
How Many Cycles Does A Battery Get?
A battery’s life cycle depends on its type and usage.
Lithium-Ion Battery Life Cycle
Most Li-ion batteries last about 500 cycles, while LiFePO4 batteries can endure thousands of cycles before capacity declines.
At Holo Battery, our customized LiFePO4 solutions have life cycle ratings of 3,000-5,000 cycles under heavy use and even higher with light use.
Normally, Manufacturers specify the depth of discharge limit to achieve these ratings.
Lithium-ion batteries are less affected by environmental and discharge factors than lead-acid ones, leading to more accurate life cycle estimates.
Lead-Acid Battery Life Cycle
A lead-acid battery can last up to 1,500 cycles with proper maintenance, especially if kept above a 50% charge.
However, its longevity depends on light discharges and correct recharge cycles. Heavy power demands or deep discharges will significantly reduce the number of cycles.
On average, it lasts 300-500 cycles.
What Reduces Rechargeable Battery Life?
Several factors, besides battery type, affect its life cycle. Understanding these can help maximize performance and longevity.
Temperature
Temperature significantly affects battery life, often causing confusion.
While higher temperatures may boost performance, they actually decrease battery lifespan, especially in lead-acid batteries. The optimal temperature for batteries is around 25°C (77°F).
One study found that lithium battery performance dropped about 3. 3% at 77°F and 6. 7% at 113°F over the first 200 cycles. As to lead-acid batteries, lifespan halves with every 15-degree increase above 77°F.
Excessive Depth of Discharge
The depth of discharge also affects battery life.
For lead-acid batteries, cycling to 50% DOD instead of 80% can double lifespan, while cycling to 10% DOD can increase it fivefold. It’s best not to discharge below 50%.
Lithium batteries are less affected by deep discharges, but it is recommended not to go below 80% DOD.
Inadequate Recharge Cycle
Fully recharging your battery is important. Completing the recharge cycle allows for a conditioning phase that reduces sulfation on lead plates.
While incomplete charges affect lithium batteries less due to their internal battery monitoring system (BMS), it’s still best to fully recharge them when possible.
Electrolyte Loss
Deep-cycle batteries contain an electrolyte solution for internal reactions.
In flooded lead-acid batteries, evaporation can leave the electrolyte behind. Neglecting to periodically refill these batteries will significantly reduce their lifespan.
Lithium and sealed lead-acid batteries have electrolytes as well. But they are sealed, eliminating the need for refills.
However, sealed lead-acid batteries can off-gas during rapid charging or overcharging, leading to minor electrolyte loss that may affect cycle life over time.
Electrode Crystallization
All batteries degrade over time due to chemical changes.
Deposits form on electrodes, such as lead sulfate crystals in lead-acid batteries and metallic lithium in lithium-ion batteries. These changes reduce the available chemicals for reactions, increase internal resistance, and can ultimately lead to battery failure if excessive.
How To Increase Battery Life?
Understanding the factors affecting your battery’s life cycle can help you extend its lifespan. Following simple best practices can maximize performance for both lead-acid and lithium-ion batteries.
- Use your battery in moderate temperatures when possible, ideally around 77°F.
- For lead-acid batteries, avoid discharging below 50% capacity; aim for a discharge depth of 10% to 50%. Lithium batteries can typically handle up to 80% depth of discharge, and sometimes even 100%.
- For flooded lead-acid batteries, keep the electrolyte solution topped off.
- Lastly, charge your battery slowly to reduce internal resistance and prolong its life.
