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Topic: Double power supply with arduino (Read 174 times) previous topic - next topic


Hi, I made a small anti-theft system with arduino, feeding it to 9v via power supply with jack.
Now I would like to insert a 6/9/12 volts battery that in case of blackout (rare) arduino remains active (and also the pir sensors etc).
Can you help me do it? however, I would like the circuit to be safe with overvoltage controls and that the battery is disconnected from the charge when it is 100%
Thank you!


The simplest solution is to choose a rechargeable battery and a charge voltage that can never overcharge it. Then just leave it on charge all the time. Normally the Arduino is powered from the charger (in parallel with the battery) and when the power to the charger fails the Arduino just keeps working.

If you have a diode to prevent the battery from back-feeding to the charger the Arduino could monitor the voltage upstream of the diode to identify when the power fails.

For information about battery charging see the Battery University website

Two or three hours spent thinking and reading documentation solves most programming problems.

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