# DoD clear definition?



## KirillSp (May 17, 2010)

Hello all!

I always hear about DoD (+any percentage), but what exactly does it mean?

Does a 100% DoD mean, that I can discharge a battery completely?

Thank you very much!


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## Duxuk (Jul 11, 2009)

DoD, or depth of discharge is a measure of how much of your battery capacity has been depleted. Battery manufacturers often quote the 20 hour capacity for their batteries but since no one drives an EV at a steady pace for 20 hours (?) this is not usually very useful. My own batteries have a 20 hour capacity of 110Ah so if I drain them at a current of 5.5A for 20 hours that will be 100% DOD. More likely I will drive for one hour. My one hour capacity is 62Ah so obviously I can draw 62A for one hour to get 100% DOD. If I let the batteries rest for some time afterwards the battery chemistry will "catch up" and I will have capacity for some more driving. I hope this helps but perhaps someone with more knowledge than me can offer some help here. What I would like to know is this-Is it as harmful to thebatteries to drain the one hour capacity (in one hour to 100%DOD) as it would be to drain the 20 hour capacity (in 20 hours to 100% DOD)?

Andrew.


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## KirillSp (May 17, 2010)

Thanks, I think I understood that (I hope ).
I think it depends on the tech specifications of your battery. Maybe you should contact the manufacturer, they would give you the specific answer regarding to your batteries!


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## IamIan (Mar 29, 2009)

DoD is the opposite of SoC.

100% SoC = 0% DoD

70% SoC = 30% DoD

30% SoC = 70% DoD

Also keep in mind long term effects.

DoD is a % of the batteries total but it doesn't mean that all batteries like __% DoD equally.

For instance if you regularly pull a Lead Acid battery to 100% DoD / 0% SoC ... it will die in much fewer years & Miles of service than if you had only done 80% DoD / 20% SoC.

As mentioned above ... keep in mind the Rate of Discharge the batteries are rated for when they do certain cycle and life testing .... 1C discharge rates will give much longer results than 2C rates... and 2C longer than 3C , etc...

So if the manufacture gives you cycle and life testing numbers based on say 1C and you are using it at up to 3C in the EV ... you should expect to get much less useful service life out of it.


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