Deep Discharge refers to reducing a battery’s capacity for discharge to 20% or less. When a battery has been fully depleted, a condition known as deep discharging, sometimes known as over-discharging, takes place. A battery stores potential electric energy when it is charged, and when it is drained, the charging process is reversed and the potential electric energy is used to power the electric components.

Each battery has a cut-off point, which corresponds to the voltage at which the battery is fully depleted. Cut-off voltages are occasionally specified by manufacturers for different discharge rates.

The discharge rates have a significant impact on the cut-off voltage. The cut-off voltage will be lower if the battery has a rapid discharge rate and vice versa. Moreover, a battery’s cut-off voltage is temperature-sensitive.

The quantity of electricity discharged during deep discharging is actually 1.5 to 2 times greater than the battery’s capacity. It is therefore extremely challenging to recharge the battery after over-discharging because the cell’s internal resistance has grown. Given the high cost of each battery, users should avoid over-discharging in order to safeguard the load and battery.

What is the depth of discharge?

The depth of discharge is a further concept to keep in mind at this point. The percentage of a battery’s potential that has been used up in relation to the battery’s overall capacity is known as the depth of discharge. The depth of discharge is 96% if the battery has a maximum capacity of 15 kWh and you only use 12 kWh of it.

Alkaline batteries are prone to leaking when they have been deeply depleted. The causes either self-discharge or are discharged by a load. Self-discharging is a phenomenon where the electric potential that a battery can hold is diminished as a result of internal chemical processes that shorten the shelf life. Deep discharge should therefore be avoided because it can damage the battery and the load.

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Yet, certain batteries – known as deep cycle batteries – are made to undergo repeated deep discharges. Regular deep discharges of these batteries consume the majority of their capacity.

The depth of discharge for a deep cycle lead-acid battery is 50%. These batteries are utilised in off-grid power storage, traffic signals, remote applications, and UPS systems.


Elliot is a passionate environmentalist and blogger who has dedicated his life to spreading awareness about conservation, green energy, and renewable energy. With a background in environmental science, he has a deep understanding of the issues facing our planet and is committed to educating others on how they can make a difference.

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