Different Voltage Output at Different Pressures

I am developing an electrolysis machine where I need to increase the voltage output of the battery as the pressure increases. I was hoping I could use a motor control with an arduino pressure sensor but I am very new to this. So I would appreciate any help from anyone in my project.

You will have to come with a LOT more details on your project if you hope to get any useful suggestions.

The first thing we need to answer is in what pressure range you are operating in: the BMP280, for example, can only operate within 300-1100 hPa, if that isn't enough, you will have to use another sensor with a higher range.
Most of these Sensors are quite well documented "Sensor name + Arduino" will normally lead to a tutorial on how to use the sensor.
The other thing you will have to consider is, how much current your machine needs and how you want to step it up/down, (If you need a voltage that is higher than the one of your battery, you will need a boost converter, if lower a buck converter and if both, a buck/boost converter combi).
Controlling these converters with Arduino isn't that simple, but I've found this tutorial which might help you:

I don't know how a motor could help you.

So some more details is that this machine is an electrolysis machine that will go underwater and will intake water and produce oxygen. The battery I plan on using is 12 volts and 17.5 amps. I plan on using speed controls to lower the voltage of the circuit. The goal is to use a pressure sensor that goes up to around 2000 kPa and will then send a signal to the arduino and the arduino will then lower the resistance of the speed control to increase the voltage to increase rates of production. If you need more information please tell me.

sriharigotluru:
So some more details is that this machine is an electrolysis machine that will go underwater and will intake water and produce oxygen. The battery I plan on using is 12 volts and 17.5 amps. I plan on using speed controls to lower the voltage of the circuit. The goal is to use a pressure sensor that goes up to around 2000 kPa and will then send a signal to the arduino and the arduino will then lower the resistance of the speed control to increase the voltage to increase rates of production. If you need more information please tell me.

Are you going to do the same to the hydrogen, so you can use it as a fuel?

Paul

So your machine needs to output a variable voltage 0 - 12 V, right? How many amps when the voltage is 12 V?
Say you want 9 V at some pressure. Does it have to be a real voltage of 9 V or can it be a PWM voltage of 12 V with a 75 % duty cycle?

Paul_KD7HB:
Are you going to do the same to the hydrogen, so you can use it as a fuel?

Paul

no, the hydrogen will be released into the water

I would go for a commercial solution:

  1. pure oxygen is dangerous, very dangerous, as many materials will spontaneously combust in pure oxygen. So your system must be designed with this in mind. A small leak can cause a fire.
  2. this sounds like a life support system.