Hello,
I've a 220v ac to 12v dc adapter. I want to charge a 9v rechargeable battery with it. So I'm going to connect the positive of the adapter with the positive of the battery and negative to negative. Then i want to connect an atemega32 across the battery. I'm going to regutate the 12v to 5v by a voltage regulator and apply this to the vcc pin of atmega32. So my 9v battery is across the 12v adapter and atmega32 is across it. I'll configure the other pins of atmega32 in some manner. So if i connect the plug of the adapter to wall socket will the battery charge and vcc pin of atmega32 be 5v at the same time?

 

Hello,
So my 9v battery is across the 12v adapter and atmega32 is across it.

ATMega32 power pins are across output of 5V regulator and ground with proper polarity.

So if i connect the plug of the adapter to wall socket will the battery charge and vcc pin of atmega32 be 5v at the same time?

Yes, if you have input 12V ito 5V regulator and taken out the 5V output and provided it to ATMega32 then you will get 5V for MCU.

Check the battery specifications. Batteries need a little high voltage like 12V battery needs 14.6V to charge. If more voltage is applied across the battery then battery will explode.

So before experimenting check the battery datasheet and confirm what is its max charging voltage. You should not apply voltage more than its max charging voltage.

 

ATMega32 power pins are across output of 5V regulator and ground with proper polarity.



Yes, if you have input 12V ito 5V regulator and taken out the 5V output and provided it to ATMega32 then you will get 5V for MCU.



Check the battery specifications. Batteries need a little high voltage like 12V battery needs 14.6V to charge. If more voltage is applied across the battery then battery will explode.

So before experimenting check the battery datasheet and confirm what is its max charging voltage. You should not apply voltage more than its max charging voltage.

Thank you for your kind replay. I'm confused about one thing if let i'm using 14v charger, my battery is 12v and atmega32 vcc pin input 5v by by using voltage regulator. Battery is across the 14v and atmega32 is across the battery. Other pins of atmega32 are configured properly. Will the battery charge and atmega32 remain on at the same time?

 

Hello,
I've a 220v ac to 12v dc adapter. I want to charge a 9v rechargeable battery with it. So I'm going to connect the positive of the adapter with the positive of the battery and negative to negative. Then i want to connect an atemega32 across the battery. I'm going to regutate the 12v to 5v by a voltage regulator and apply this to the vcc pin of atmega32. So my 9v battery is across the 12v adapter and atmega32 is across it. I'll configure the other pins of atmega32 in some manner. So if i connect the plug of the adapter to wall socket will the battery charge and vcc pin of atmega32 be 5v at the same time?

At the very least - you have to limit the charging current to the battery.

most rechargeable batteries have some nasty habit or other - lithium tends to vent with flaming gas if you don't precisely regulate the full charge terminal voltage. Nickel chemistry exhibits a decreasing terminal voltage with temperature rise - just as you think you've limited the current just right, the tempco screws it all up.

 

At the very least - you have to limit the charging current to the battery.

most rechargeable batteries have some nasty habit or other - lithium tends to vent with flaming gas if you don't precisely regulate the full charge terminal voltage. Nickel chemistry exhibits a decreasing terminal voltage with temperature rise - just as you think you've limited the current just right, the tempco screws it all up.

Is 500uA current from charger to the battery while charging is safe?

 

Is 500uA current from charger to the battery while charging is safe?

Let me consult my crystal ball.......................something is emerging from the mist, I see a PP3 shirt pocket radio battery.

That might not overcome self discharge leakage on nickel chemistry - I assume a lithium would eventually exceed its maximum safe terminal voltage, but I don't know what would happen because I was never stupid enough to try it.