What is depth of discharge (DOD)?


What is depth of discharge (DOD)?

DOD, also known as “Depth of Discharge” is used to describe how deeply the battery is discharged or should be discharged. If we say a battery is 100% fully charged, it means the DOD of this battery is 0%.

When a battery have delivered 30% of its energy and having 70% energy left, this means that the battery is at 30% DOD. A battery that is totally used is at 100% DOD.

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Depth of discharge and cycle life

Most battery chemistries (including lead-acid and lithium-ion) degrade as they are charged and used up, gradually reducing their ability of storing energy till they can no longer store energy again. This affects the length of the battery’s operational life, as well as the total number of hours it will be able to store over that lifetime.

Let us consider two factors out of other factors that can cause this:

  1. The number of discharge-recharge cycles, and
  2. The maximum depth to which they are discharged.

If a lead-acid battery is discharged/used to 100% of its power storage capacity every time it is used, its electrolyte will quickly degrade and the battery might not be able to retain energy like it used to do anytime it is been charged compared to if it were only discharged to a maximum of 50%.

This is why the term ‘cycle life or cycles’ (with the qualifier ‘at X% DoD’) is used on battery information board.

Depth of discharge (DOD)

All battery manufacturers recommend to keep the Depth of Discharge (DOD) below the maximal limit of 100%. Ideally 80% DOD or less is recommended. This means that when using your battery, you should ensure that only less than 80% power capacity is used before recharging again.

As a matter of fact, since it is better to avoid deep cycle discharging, it seems to be better to charge as frequently as possible. It is better to “charge (to full) before use” rather than “empty and charge”. 



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  1. Oluseye May 18, 2017 at 5:14 pm

    How can one restore the DOD of a prag 200Ah battery that is just about 1 year old but discharges within 30 minutes when it shows fully charged?
    I have come to the conclusion that using generator (7.5KVA) to charge inverter batteries actually kills the battery as this has been the case of all my 4 batteries.
    Would appreciate you advise on how to restore life back to my batteries.

    • olanrewaju matthew May 22, 2017 at 10:28 am

      Dear Mr Oluseye,
      Charging your inverter batteries with generator will not affect their performances if the generator is in good shape (Voltage and frequency) and the batteries are adequately charged on every occasion before usage. Recovering a sulphated battery is a 50/50 situation. A visit to your local battery charger shop can help.

  2. Uche May 18, 2017 at 6:20 pm

    Good and informative. I now know why I would not use a battery for six months before it begin to behave abnormally; get charged fully in a few minutes and discharge fully in another few minutes say 10 minutes. I really got tired of batteries and I thought it’s not worth it. Anyway please let me know if you have a mitigation to Full discharging, I mean can there be a means of ensuring the battery don’t get fully discharged and stop discharging say after about 60% of its energy has been used. I also want to know the price of the batteries if there is any such.

    • olanrewaju matthew May 22, 2017 at 10:44 am

      Dear Mr Uche,
      Thank you for the compliments. Battery usage and charging patterns goes a long way in determining battery life.
      Our brand of inverter like the 4kva,3kw,6kw etc has a depth of discharge features where you can set your preferred value. It will ensures your battery is not drain beyond set values thereby prolonging the cycle life.

  3. Olaniyan Ayobami. O May 18, 2017 at 8:01 pm

    Comment pls kindly let me have the price for all the above product. And their duration of work. I am desperate in need of it pls. Thanks and God bless

  4. Ade May 18, 2017 at 8:47 pm

    Latest price list for 7 to 10 kva pls

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