How can I avoid using different batteries to power different components in a circuit board?
You could use a voltage regulator to create 3.3V from the 14V batteries. Since the device is running from a battery, I would avoid a linear regulator as the power loss would be $$P_{loss} = (14.4V - 3.3V) * I$$ This may be acceptable for your application but I would rather use a switch mode voltage regulator for increased efficiency.

When choosing a suitable regulator, you would need to check the datasheet and make sure it can function at a larger temperature than 150 degrees C. This is especially important when using a linear regulator as the power loss is converted directly to heat. 

How much larger the temperature rating should be, we cannot tell without knowing more details of your application.

Without going into much detail about designing systems from a heating perspective (and to learn more about the topic) see this excellent video from Dave Jones at the EEVBlog (https://www.youtube.com/watch?v=8ruFVmxf0zs)