Battery Lifetime - Depth of Discharge (DoD)

 Depth of Discharge (DoD)

 

Introduction

Normally all of battery does not have the same lifetime although it’s the same capacity (Ah) or model. So battery can be used long or short time is depending on number of cycle charge and discharge. Battery has limited number of cycle charge and discharge “Cycle Service Life”. When the battery’s number cycle of charge and discharge reach to limited point, so the battery will be death.

It also does not mean all of battery has the same number of cycle charge and discharge too. Depth of discharge (DOD) is a reason that effect to changing number of cycle charge and discharge. So we need to know about depth of discharge to protect our battery.

 

Keyword--- Depth of Discharge (DOD), State of Charge (SOC).

• Depth of Discharge (DOD) is taking about discharge current from battery. So DOD is the percent of ampere hours (Ah) was discharged or amount energy has removed from battery.

• State of Charge (SOC) is the percent of ampere hours is still available in the battery can be used or we can said the capacity store in the battery.
  

Figure 1: Depth of Discharge and State of Charge

Example: One battery fully capacity in 100Ah (Battery 100Ah). We discharge total 30Ah to load (e.g lamp, fan, TV….). So it mean 30Ah (30%) is depth of discharge and 70Ah (70%) is state of charge.

 

Figure 2: Table of DOD and SOC

Why we said depth of discharge effect number of cycle charge and discharge?

• DOD (100%)         Number of cycle is 200 to 270.

• DOD (50%)           Number of cycle is 425 to 525.

• DOD (30%)           Number of cycle is 1050 to 10250.
  

 

Figure 3: Graph Number of Cycles

Reference

[1]        Luminous Power Technologies Pvt. Ltd. [INDIA]

 

[2]        https://www.cleanenergyreviews.info/blog/simpliphi-pylontech-narada-bae-lead-acid-battery

 

[3]        https://www.sciencedirect.com/topics/engineering/depth-of-discharge

 

[4]        https://battlebornbatteries.com/depth-of-discharge-li-ion-deep-cycle-batteries/