battery discharging circuit/ battery full charge detection

[haneef]

Hello...I want to build a circuit for battery discharging...or even to detect a battery when it is fully charged.....can anyone please help me??

 

[neon]

to discharge a battery all you need is a load. If you want to discharge it at a certain rate just put a power transistor across and vary the base. to detect a fully charge battery a comparator will do it or even a LED if designed carefully

 

[(*steve*)]

It also depends on the battery type (a lot).

Detecting discharge is usually based on voltage (but that voltage varies with load)

Detecting a full charge is sometimes based on voltage alone, sometimes often there's a top-up charge applies after reaching a certain voltage. Other battery types a full charge is indicated by the rate of change of temperature, or even a small dip in the voltage.

 

[haneef]

Hi der...thanx alot for your reply..actually i am a little weak in practicals..can you guys please tell me how to attach the load...i want to discharge the battery after it is fully charged or i want to connnect an led showing full charge...can you please show me the circuit..please...u can email it to me at [email protected]

 

[(*steve*)]

A load is anything that you connect to the battery causing current to be drawn. It could be a lamp, a resistor, or some fancy electronics. Here is a simple example.

To determine when the battery is fully discharged you need to know (at a minimum) what type of battery and what nominal voltage it has.

To connect a LED showing full charge, well, that is a complex topic...

 

[GreenGiant]

You need to disconnect the charging circuit in order to check if the batery voltage is equal to full voltage.,
otherwise it checks the charging voltage and detects, which is wrong. there after you can use a simple compare to detect the voltage.
Load must also be disconnected.

Not entirely correct, you can check a battery's true voltage while it is charging if the voltage reading comes directly from the tabs of the batteries

This should yield the voltage of the battery, rather than a charge/discharge voltage, though you will sometimes get discrepancies when close to fully charged/discharged

 

[BobK]

Not entirely correct, you can check a battery's true voltage while it is charging if the voltage reading comes directly from the tabs of the batteries

This should yield the voltage of the battery, rather than a charge/discharge voltage, though you will sometimes get discrepancies when close to fully charged/discharged

Plus the internal resistance times the charging current.

Bob