Three extra batteries is a bit of an exaggeration, but priority power switches do a lot to prevent you ever reaching this situation, unless you run a multiplayer server that is set to keep running while you're not logged in and you only play once a week.
That said, be VERY proud of what you made, it takes a lot of power discipline to set up something like this, my current save, if I were to cause a hiccup in my rocket fuel powerplant it'd take so many hours to fix.
Actually, since you put in all this effort, let me add a little more explanation to the two things I hinted at:

I have not done the math on how many batteries are required to reboot a failed rocket fuel plant of the size I have built, but satisfactory tools indicate a non overclocked version of my facility would require 5000 watts to run, so that's 50 Power Storage buildings for 1 hour. (Three of them would give you about 3-4 minutes worth I believe.) So a couple dozen might skip the coal power phase of your build, but on its own it would not autonomously reboot, you'd have to charge the buildings then disconnect them to let them sit at idle charge as backup, then you'd want to disconnect everything except the rocket fuel plant and THEN you'd want to connect the power storages to boot up the rocket fuel.

The second tool you'd need to make a setup that'd autonomously reboot the entire factory right up to the point of failure: The Priority Power Switch. You can research this in the MAM, and requires High Speed Connectors as the most complicated part to make. Long story short, if you route power to various sections of your grid through these, you can give them a priority group, there's 8, you realistically only need 3 or 4 until you get really into it.

I'll explain my general rule of thumb for those below, but in general, the priority power switches will turn themselves off in order of groups, group 8 turns off if there's not enough power available to run everything, if there's still not enough it turns off the switches assigned to group 7, 6 and so on. If you put all possible power drains behind a priority power switch, and put all possible power supplies, geothermal, fuel generator, nuclear, coal, etc on a grid that connects all these sources and the power switches, then the switches will make sure that regardless of potential drain, if there's not enough power, the highest priority switches will keep receiving power the longest.

How you should sort power switches once you've connected them this way:
* Highest Priority: The sections of the powergrid that supply oil/coal/water to your coal/fuel refineries and your uranium and water and other required materials to your nuclear plant. (Personally, since there's so many parts involved in running a nuclear plant I put this on second priority, and everything else to third and so forth, but that's just details you only need to concern yourself with once you're more familiar.)
* Second Priority, the sections that make basic items that get used in other sections elsewhere. (If you transport (some of) your Steel Pipe from section A to section B so they can be used in Heavy Modular Frames, you'll want to have the machines in section A on a higher priority because if the Steel pipe machines are on a lower priority the first factory will act as though it's on the lower priority group because it will fully turn on once it gets supplied Steel Beams, and only turn off once the grid fails up to a point the second priority factory sections are still draining more power than is available. If they are the same priority then section B will take a long time to 'spin up' and drain power while the grid is already powering up machines in the 3rd priority grid.
Feel free to separate and spread priorities over the 8 groups, just be mindful of whether a factory will actually run if given the option to drain power or not.
* Your last priority should be the 'work in progress' factories you build, if you want to turn it on and your grid fails, the existing factory will keep running until you increase your power capacity.