battery serie and parallel

[kidsnoob]

Hello.

For my first ever post on the forum i will ask your help on a battery question.

im not an electronic engineer and i need for my project to have 2 "power setting "
in this small electronic schematic:
View attachment 64441
If both the battery are 5 volt, does LS3 get 5V and LS5 get 10V ?
also, is that secure?

Thank you all for your input.

 

[strantor]

I say, assuming your diodes have zero voltage drop and the batteries have identical internal resistance, LS5 gets 10V and LS3 gets 7.5V. not 100% sure about that though.

 

[JimB]

LS5 will see 10 volts.

LS3 will see 10 volts minus the volt drop of two diodes. Assuming silicon diodes, the voltage will be 10 - (2 x 0.6) = 8.8v

JimB

 

[strantor]

I said LS3 would get 7.5V because it is connected to the NEG post of both batteries. I assume this creates a voltage divider because of the battery internal resistances. Is there an merit to this?

 

[kidsnoob]

Thank you very much!

 

[colin55]

The first thing to do is simplify the circuit.
Diodes D2 and D3 do not have any effect as the voltage across them is more than 0.7v
This produces the attached circuit. You can clearly see the voltage to the two heaters:
View attachment 64449