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CCCV lead-acid battery charger

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Mechatrommer:

--- Quote from: Siddhat on June 23, 2020, 05:09:54 am ---
--- Quote from: Mechatrommer on June 22, 2020, 04:06:06 pm ---https://circuitdigest.com/electronic-circuits/float-charger-circuit-for-12v-sla-battery and many more circuits in google (keyword "sla charging circuit")

--- End quote ---
The circuit is explained well. When the battery is charged the relay cuts off the charging voltage, but, when the battery again discharges the relay again turns ON the charging voltage. This causes tripping of relay. Now, can a hysteresis be added to the op-amp, to overcome this?

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add resistor (maybe 10-100K ohm) from relay pin 4 to LM358 inverting input (pin 2)


--- Quote from: Siddhat on June 23, 2020, 04:30:12 am ---
--- Quote from: Benta on June 22, 2020, 09:34:52 pm ---For lead-acid, you only need a CV charger with current limiting. If it has to be fancy, include ambient temperature measurement for the CV part.


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The voltage at the output of the buck-boost converter is set by the voltage of the battery. So,the current has to be controlled. For that, in the Constant Current stage, limiting the current output of the buck-boost to the initial current of the battery is a good idea but once the battery voltage rises and reaches the Constant Voltage stage, does the exponential current drop happen automatically? or, has the current be controlled in such a way that it drops exponentially when it reaches in the CV stage?

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the simplest current limit/control "programming" is using power resistor (maybe 1-10 ohm) on buck-boost output to battery.

Benta:

--- Quote from: Siddhat on June 23, 2020, 04:30:12 am ---
--- Quote from: Benta on June 22, 2020, 09:34:52 pm ---For lead-acid, you only need a CV charger with current limiting. If it has to be fancy, include ambient temperature measurement for the CV part.



--- End quote ---
The voltage at the output of the buck-boost converter is set by the voltage of the battery. So,the current has to be controlled. For that, in the Constant Current stage, limiting the current output of the buck-boost to the initial current of the battery is a good idea but once the battery voltage rises and reaches the Constant Voltage stage, does the exponential current drop happen automatically? or, has the current be controlled in such a way that it drops exponentially when it reaches in the CV stage?

--- End quote ---

This is correct, but "current control" is overkill. Current limiting is enough. The current will drop by itself when the charge voltage has been reached.

Siddhat:

--- Quote from: bin_liu on June 23, 2020, 12:53:58 am ---This is a previous project, and the accessory is a small power product, you can refer to it.
The attachment is a circuit diagram of an RCC topology, which is also applicable to the flyback topology.

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The jpg file doesnot open. Will you upload once more?

bin_liu:
look here,It‘s a PDF file.

trobbins:
Siddhat, I suggest you do more background reading on lead acid battery charging to appreciate better what is happening in the battery and how a typical charger works.  You also need to elaborate on your project, as there is no detailed information except that it is a lead acid battery.  I suggest you also get your algorithm reviewed, and perhaps even set up a simple manual charger and follow your algorithm through by manual changes.  Nobody knows what you are aiming to really do, and batteries can be hazardous when ill-treated.

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