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Battery provides a constant potential difference all along its life time? Answered

Will a 12 Volt battery provide the same potential difference of 12 Volt even after using it for long time? Or it will decrease from 12 v to 11.5 and then 11.1v  and then to 10 v ...................5v.............3v.................0.5v,0.1v and then at last 0v with usage? Give reason if it works as constant source of potential difference supplying agent.

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Battery uses chemicals to give power. Charging, discharging & the charging rate decides the life of any battery. But during these cycles, the chemicals in the battery including anodes & cathodes gets depleted.

Each time you charge & discharge a battery, it gets depleted a little. After a while it will loose the capacity of holding the charge. That is if you charge it , it will show 12 V but as soon as you use it it will go put immediately. That is " dead " battery.

It can work as constant source of potential difference supplying agent but it will be measured against time. It will work that way for a particular time - not permanently.

We are more fun and unpredictable :-)

The agent might affect how rapidly your battery discharges.
But then again you can charge the battery and again discharge it.
These cycles can be repeated 1000 times before the chemistry in a
battery gets degraded to final failure.

A

As long as the battery is in good shape (charge-wise) it will deliver a voltage around 12V. Without load, the voltage will be somewhat above 12V, with load it will depend on the current consumed (due to the voltage drop at the inner resistance and limited speed of chemical reactions). While a load is applied, the battery will get discharged and the voltage will drop. In theory, the voltage might go down to something near 0V. But normally the electronic circuit attached will stop working earlier. If the load is removed, the voltage may rise again due to the internal equalization of chemical reagents.

So, in short: 12V is just the nominal voltage. A good point to start calculating your circuit (while keeping in mind, that a fresh battery will have slightly higher voltage and the voltage will drop.

To know, how the voltage curves look, when a battery is discharged, you have to take into account the chemistry of the battery (lead, mercury, zinc carbon etc.), the consumed current and even the ambient temperature.