Question: I'm just curious if it's possible to power 2 devices at different voltages with a set of batteries while making sure that the 2 devices makes use of all the batteries. I have here an illustration of the connection that I would like to get verified. [![Each battery is rated ***n*** volts](https://i.stack.imgur.com/Q846m.jpg)](https://i.stack.imgur.com/Q846m.jpg)

Each battery is rated ***n*** volts 

I used dashed lines in 2n volts connection for ease of seeing. 
I want to power each device with 4n volts and 2n volts[![An Alternative Illustration](https://i.stack.imgur.com/YEZa5.jpg)](https://i.stack.imgur.com/YEZa5.jpg)

An Alternative Illustration^

The solution that I propose is to connect 4 batteries in series first to power 1 device. Then since there can be 2 sets of batteries in series already I can connect these sets in parallel for the Voltage to **not** add up. However, just by looking at the circuit I think some portions are actually shorted. 

Any help would be appreciated. *Please don't be harsh if this is a dumb question.*

Answer: 
No. Your attempt to power a 4n load, and and 2n load from balanced batteries, shorts out each 2n battery.

You have two (or three) options.

a) Power the 4n load, and a 4n->2n converter to power the 2n load. This could be a linear regulator if the power level is low enough for you to not worry about the inefficiency and heat. Better though would be a buck regulator.

b) Configure the batteries as 2n, and power the 2n load, and a 2n->4n boost converter. Choose (a) or (b) depending on which load draws more power, or the convenience of having a buck or boost converter to hand.

c) Power the 2n load from a battery tap, and tolerate the consequences of the imbalance (replacing batteries earlier, or charging differently)

d) Power the 2n load from a switchable battery tap, so you spend 50% of the time powered from the 'top' batteries, and 50% of the time from the 'bottom' ones. Obviously you cannot common the grounds if using it like this. 

e) Use a 2n set and a 4n set of batteries. You need more batteries, but get complete freedom.

Ok, so 5 options.
Wouldn't adding a pair of diodes solve the issue? If the current isn't something massive I think it would be fine no?![Professional drawing](https://i.stack.imgur.com/e1qvi.jpg)