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What Is Depth of Discharge (DOD)? Complete Guide for Solar Batteries 18/ 2025.Ноя

What Is Depth of Discharge (DOD)? A Simple Explanation

Depth of Discharge (DOD) describes how much of a battery’s stored energy has been used.
Example:

  • If a 10 kWh battery uses 5 kWh → DOD = 50%

  • If it uses 9 kWh → DOD = 90%

The higher the DOD, the more the battery has been discharged.

Why DOD Matters for Battery Life

A battery’s lifespan is closely linked to DOD.

  • Lower DOD = longer lifespan

  • Higher DOD = more stress on batteries

For example:

  • Lead-acid batteries:recommended DOD 30–50%

  • Lithium (LiFePO4) batteries:can safely reach 80–95% DOD

This is why lithium batteries last much longer than lead-acid.

How DOD Affects Cycle Life

Cycle life means how many times the battery can fully charge and discharge.

Тип батареиRecommended DODЦикл жизни
Свинцово-кислотные30–50%300–600 cycles
NCM Lithium70–80%800–1,500 cycles
LiFePO480–95%3,000–6,000+ cycles

LiFePO4 batteries are popular for solar systems because they maintain long cycle life even at high DOD.

State of Charge (SOC) vs DOD

  • 100% SOC = 0% DOD

  • 20% SOC = 80% DOD

Example:
If the battery is 20% full, the DOD is 80%.

bluesun lifepo4 lithium battery

What Is the Best DOD for Solar Batteries?

For home energy storage and solar systems:

🔋 LiFePO4 (LFP) batteries:best DOD = 80–90%

  • Stable chemistry

  • Very long cycle life

  • Safe for deep discharge

🔋 Lead-acid batteries:best DOD = 30–50%

  • Deep discharge greatly shortens lifespan

  • Not ideal for daily solar cycling

How to Choose a Battery Based on DOD

When choosing a battery, look for:

  • Rated DOD (e.g., 80%, 90%, 95%)

  • Cycle life at that DOD

  • Warranty terms

  • Daily usage scenario

If you use the battery every day (solar system, backup system),choose a lithium battery with high DOD and long cycle life.

Real Example:10kWh Battery with 90% DOD

  • Usable energy = 10 kWh × 90% = 9 kWh

  • If the DOD was only 50% → usable energy = 5 kWh

Higher DOD gives more usable power and better efficiency.

Заключение

Depth of Discharge (DOD) is a key factor in choosing the right solar battery.
A higher DOD means more usable energy, but only lithium (especially LiFePO4) can handle high DOD while still keeping long lifespan.

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