CCCV constant current constant voltage

Thread Starter

Salah king

Joined Oct 27, 2022
3
Hello
I would like to understand the behavior of the CCCV control, which is used to charge and discharge the battery.
as I know the CC will work at the beginning till the voltage of the battery reaches to the desired voltage then CC will stop,
the charging mode is switched to CV, and converter operates, keeping the output voltage constant while current starts decreasing.

If there any demo model (MATLAB file) can describe this behavior more will be very helpful.

Thanks in advance.
 

BobTPH

Joined Jun 5, 2013
6,082
What more is there to describe? Your post already says everything you need to know, other than the specific current and voltage which depends on the type and capacity of the battery.
 

KeithWalker

Joined Jul 10, 2017
2,620
A single cell Lithium-ion battery is usually charged to 4.2V, so a 4.2VDC supply is used. It has a current limiter, set to limit the current to the maximum recommended charging current for the battery. If the battery is discharged, the terminal voltage will be less than 4.2V so it will draw the maximum available current from the supply. As the battery charges, and the terminal voltage approaches 4.2V, the current will decrease until the battery voltage equals the supply voltage, when no more current will flow.
In an actual battery charger, the supply cuts off when the current falls to 1/10 of the maximum charge current.
 

crutschow

Joined Mar 14, 2008
31,129
If there any demo model (MATLAB file) can describe this behavior more will be very helpful.
Here's a simple LTspice functional simulation of charging a battery, but don't know how that might translate to MATLAB.
R1 and C1 are a simple battery model.
C1 represents the battery capacity, and R1 represents the charge current when the battery reaches full charge.

The battery is charged at 1A constant-current (red trace) until the voltage reaches the V1 10V (green trace) causing the switch S1 to close, at which point the S1 switch shunts the I1 current, leaving the battery at that voltage.

1667491562507.png
 
Last edited:

Audioguru again

Joined Oct 21, 2019
5,420
The graph I posted shows that when the lithium battery voltage equals the supply voltage then the battery is still charging for a fairly long time before its charging current slowly drops to a low amount and then the battery is fully charged and the charger shuts off. A lithium battery must not be trickle charged and the lifetime is less if maximum charging current (and resulting max heating) is used.
 

KeithWalker

Joined Jul 10, 2017
2,620
Lead-acid batteries have a very similar charging profile to Lithim-ion batteries but with different terminal voltages and internal resistances.
 
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