Two loads voltages

Hi guys! I hope that you can help me with this issue. I'm actually working on a project that has a 12V 5000mah battery and an ac plug. I want to use the battery as a power not the main source. I want to build an automatic switch that stops the voltage of the battery when the ac plug is connected to the wall and the battery to take over when it's unplug. I don't want to use relay because they consume too much power and also i dont want to use two diodes because the voltage across the battery is higher when the battery is fully charge. Thanks in advance for your feedback!

by samybee
April 21, 2017

I would suggest using power FETs as switches, one to connect the battery and one to connect the mains power supply. It may be a good ides to have an intermediate store such as a capacitor to provide the supply voltage during the short time it takes to sense the presence/absence of mains voltage and switch from/to battery, and a diode in series with the mains supply to decouple it for sensing. The detail design will depend on your exact requirements.

by mikerogerswsm
April 24, 2017

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