Power supply and battery charger

[tnnedaboard]

Hi,

I have a circuit with average absorption 300mA
I want to use a power supply from battery (12V 7Ah) and Transformer (AC / DC)

Can I follow the wiring diagram attached to make the circuit even when the battery is charging?

I would use a battery that type of UPS, for example.:
https://it.rs-online.com/web/p/batterie-al-piombo-ricaricabili/6142469/

 

[AJBotha]

I dont understand, what do you have and what do you want to accomplish?
Do you want to use a 12V battery to power an AC circuit or where does the transformer come in?
Or do you want the transformer to charge the battery?

The schematic that you have attached takes 14V DC input,
then regulates that to something between 8V and 12V DC,
then regulates that output to 5V DC.
The capacitors are used for filtering.
The 5V output can supply around 1A.

 

[tnnedaboard]

I'm sorry, I try to explain better ...

the circuit must operate with the battery ...

I want to make the circuit work (VCC out and +5 V out) even when the battery is charging .. OK?

The circuit should work (VCC out and +5 V out) even when the battery is not present ... OK?

 

[Audioguru]

The 14VDC input to the charger is too low to charge the battery.
The battery will be about 13.8V when fully charged. The diode will have about 0.7V across it so the output of the LM317 should be 14.5V when its load current is low.
The LM317 needs an input that is at least 1.8V higher than its output so its input should be at least 16.3V. Use 18V.

The battery charger provides about 600mA. The load uses 300mA. Then there will always be 300mA to 600mA available to charge the battery even when the load is powered.

 

[tnnedaboard]

thanks,

I do only the following changes:
Vin = 18Vdc
OK?
If I wanted to have the charger, more than 600mA when it is used to power the circuit?

 

[Audioguru]

I do only the following change: Vin = 18Vdc. OK?

Yes. But the LM317 will get hot when the battery is discharged so it will need a good sized heatsink.

If I wanted to have more than 600mA for charging, when it is used to power the circuit?

Then reduce the value of the 1 ohm resistor. But then the battery might be over-charging and might boil if the circuit is not powered.

 

[tnnedaboard]

Hello,
thanks to your recommendations, I got the attached diagram ...

but I have some questions ...

When the battery is not connected, how much current can I pick up dal'out 12/13, 8V?

The maximum current of the power supply input should be 0.6 A (charging batt.) + Current circuit max + 10%?

 

[tnnedaboard]

Help, thanks

Hello,
thanks to your recommendations, I got the attached diagram ...

but I have some questions ...

When the battery is not connected, how much current can I pick up dal'out 12/13, 8V?

The maximum current of the power supply input should be 0.6 A (charging batt.) + Current circuit max + 10%?

 

[Audioguru]

The 1 ohm resistor feeding the BC547 transistor limits the current to 600mA. You can have 300mA at 13V plus 300mA at 5V or any combination that adds up to 600mA.

 

[m.mokhtar]

The charging voltage must be 14.6 to 15 v, and when the battery is charged the voltage of the charger must be lowered to 13.6 to 13.8 v max otherwise the battery will be overcharged and its life span will be decreased .

 

[Audioguru]

Hello
How to charge a battery without a designated charger. With technical knowledge, batteries can be charged manually with a power supply.

Thanks for providing information.

Only an old fashioned lead-acid battery (like in your car) can be charged like this.