# battery serie and parallel

Hello dear Arduino community.

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:

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.

I would wait for someone else to comment(I'm no EE either), but it looks like if this works then LS5 will get double the voltage and half the current as LS3(It won't be 5 and 10V though, since there's a voltage drop across the diodes).

You might want to take a look at this Java-based circuit simulator: http://www.falstad.com/circuit/

A little careful thought will show that D2 and D3 must be reverse biased at all times and are thus redundant, you'll then see that both lamps get 10V (although one is a bit less due to the diode drops).

Basically if the batteries are in series they cannot be in parallel. You can arrange for switches to switch between the two configurations though.

LS5 gets 10 volts.

LS3 gets 5 volts less two diode drops (with twice the current capacity).

Don

You don't need any of the diodes. If you redraw the circuit to its simplest configuration (2 diodes removed as already suggested and the other 2 replaced by solid links) you will find that both batteries are in fact in series with one lamp across one battery and the other across both.

You don't need any of the diodes....

But now LS3 has less current available.

Don

Wrong! The current is determined by the resistance of the load and the voltage delivered to it (if you ignore the internal resistance of the battery)

Wrong! The current is determined by the resistance of the load and the voltage delivered to it (if you ignore the internal resistance of the battery)

You should be a lot more careful before you say that something is wrong.

The amount of current that is drawn is determined by the resistance of the load and the voltage delivered to it.

The amount of current that is available is determined by the characteristics of the source.

Don

Indeed it is and that’s why in parenthesis I said “if you ignore the internal resistance of the battery”
Note that the original question related to batteries, hence my qualified (and I believe, correct) response.

I’m terribly sorry that I misinterpreted the original problem. I thought he was talking about a real circuit that he intended to build. I didn’t realize that he was talking about a mythical circuit with ideal batteries.

Don

Let me know when it's time to lock this thread.