Batteries in parallel with a diode

AI Thread Summary
Connecting a 17V DC source in parallel with a 9V battery that has a diode will prevent current flow into the battery due to the diode's reverse bias. The voltage drop across the diode and the 9V battery will equal the 17V DC source, resulting in no current flow in the circuit. To protect the battery from discharging back into the 17V supply, a diode in series with the 17V source is recommended. This setup ensures that the battery only provides power if the 17V source fails. Overall, the configuration effectively isolates the battery from the higher voltage source.
quantumlight
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I was wondering what the effects are if any if I connect a 17V DC source in parallel with a 9 V battery but the 9 V battery has a diode that prevents current from flowing into it. Thanks
 
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That's OK. Did you want the 9V battery there to give a supply if the 17V fails?
You may also want a diode in series with the 17V supply to prevent the battery discharging back into it when it fails (in case there is a path to Earth inside the 17V supply).
 
quantumlight said:
I was wondering what the effects are if any if I connect a 17V DC source in parallel with a 9 V battery but the 9 V battery has a diode that prevents current from flowing into it. Thanks

no current will flow through the circuit as the voltage drop across the reverse biased diode and the 9V battery will be equal to 17V DC source
 

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