Okay, this took me a good while to research, consult, and rethink, so I apologize for the delay. Honestly, what I have in mind now is essentially matter for a different topic. I should update the original post, but meh, another time.
Alright, so, what do I begin from? Maybe a bit about how electricity works in reality, very, very roughly.
First off, batteries, cars, and other appliances are not interoperable due to different voltage of their systems. For example, AA batteries are 1.5V, alternators output 12V, with some 24V ones existing. Car batteries and other “bigger batteries” are more or less always 12V, with 24V and higher voltage ones consisting of multiple 12V subbatteries. On the other hand, the voltage that you find in an outlet is usually something like 110/120/230/240 or so. Specifics don’t matter for Cataclysm, because we’re essentially free to pick whatever with the excuse of “power technology changed enough to leave little artifacts from the past” - if it’s more advanced, conversion between different voltages is not hard anyway, it just incurs some losses.
Second property relevant to Cataclysm is amperage, which is essentially the maximum amount of power that a device can output/consume. Important to note is that it’s directly related to voltage - a 4V battery that outputs 2A, converted into 8V will only output 1A(actually less due to losses). You would need roughly two of them to output 2A at 8V.
Power transmission is relatively simple, and is a both-ways process, although the lower the voltage, the greater the losses will be, which is why transmission lines usually have voltage on the order of hundreds of kV(kilovolts). Power conversion is likewise simple, although it entails losses. There is a huge amount of different types of transformers/voltage converters, but, for the most part, we can ignore that and have just one - future tech, right? Most of them are inside electronic appliances anyway - we can just implement “universal transformers” of different sizes - small, normal, big, huge(power substations), since size is essentially all that is important - too small of a transformer will overheat, and so will cables.
Also, there’s alternating and direct current, but conversion between those isn’t extremely hard, and can be completely abstracted for the sake of simplicity - it would already be possible nowadays, and Cataclysm has future tech that is magic.
Next up, batteries - in reality, it wouldn’t be the power grid that would die - power plants would most likely remain operable once you reboot and maintain them a bit. Particularly higher generation nuclear power plants have virtually no chance of breaking down fully. The thing that would die is storage devices - the 0-100% of any battery that we can find is in reality something like 75-100% of its actual capacity - the problem is that voltage falls as the charge falls, and even more importantly - the battery degrades. Within few months of an apocalypse, batteries would be rendered unusable forever, and that goes for ALL of them. That said, we probably for sure don’t want that, because that would mean that cars are no longer operable, and honestly - neither is anything else electricity-powered because without power storage, nothing runs, and even to kickstart an engine/generator, you need power. Not to mention the fact that batteries are not easy to make.
Speaking of generators - an alternator generates extremely little power, relative to how much house appliances or welders consume. A car battery can output high amperage, but it can’t output it forever - you could power a welder off a car battery for… I don’t actually know the figures, but not for a long time. The point is that an engine sporting an alternator would take many, many times more time to charge that battery up. A proper power generator converts maximum possible amount of engine’s energy into electricity, whereas an alternator converts little enough that you could attach 10 of them without a problem - it’s a negligible amount compared to the actual output of an engine.
Also, some more info: Some voltage converters are two-way, but they’re bulkier than most used nowadays(although, at the same time, they don’t scale up nearly as well as toroidal transformers), so let’s just have huge two-way toroidal transformers in power substations, and universal differently-sized ones elsewhere. Which means that compatibility between different devices is a matter of interface(i.e. battery slot vs power plug/outlet vs car cables). That said, said converters would be most likely embedded in the devices(or rather, their cables, but we can just abstract that), and would not matter for any practical purposes.
That last paragraph carries a huge significance for powering houses - if you just connected a generator in a house, the generated power would simply dissipate through the grid, powering nothing.
Also, carrying information through electricity cables is perfectly viable, and if we just assume that futuretech rebuilt the power grid, that will let us get away with a lot of stuff further down the line. E.g. a generator will be able to adjust its power output depending on what it has to power without a problem.
Alright, I’m somewhat poor at writing, so just like this, I will poorly transition into talking about my renewed proposal. First off, I propose the following standard voltages for different objects, with conversion being relatively simple: 4V DC batteries, 12V AC car power, 120V house power, 120kV transmission. Next off, cables. I propose three - small for battery-powered devices and primarily for use in crafting recipes, normal for cars and house - let’s just assume everything has built-in converters, and huge cables for transmission. Thirdly, differently sized universal converters that can support up to N amps, used as parts of electrical recipes. Fourthly, power consumption adjustment - for example, a welder would burn through hundreds of batteries in the matter of seconds, and as such I propose converting such devices to grid-powered once the infrastructure is in place, and most likely gasoline-powered before that. However that works.
Well, truth be told, I’m feeling somewhat shitty at the moment, so I can hardly be arsed to elaborate on that more, I’ll just continue writing my research and thoughts, someone else feel free to comment on it and format it up. Also, from this point on, draw your own conclusions. Depression, apathy, and all that stuff.
So, let’s assume that future tech has vastly improved batteries, so let’s say they don’t break down, that they have much(~3-4x?) greater capacity, perhaps 2x the amperage(maximum power output at a given point), and are recharged much faster but not instantly. This means, cord mods for battery-powered tools - lower throughput variant for charging, higher output one for replacing battery systems. Power outlets installable both on cars and walls/floor. Cables similar to current jumper cables, but with in/out ends(tools would only have cords with an in end), except I’d like them to not phase through walls, and be visible during laying them down. As Kevin said, electrical furniture/objects can just be vehicles secretly, perhaps ones that can be put inside inventory sneakily. Since vehicles are reality-bubble independent, particularly the electrical connection graph, some hack could probably be devised to generate noise and lay cables through Z levels. Also, some way to put cables inside walls. Perhaps some sort of flow simulation. Oh, and yeah, since we have information over wire, have a stat screen on generators, how much power is needed, how much is generated, how much can be generated, etc. Also, breakers to disconnect from the grid.
Oh yeah. If you convert from 12V to 13V on a battery, you can drain it dry in favor of another battery. So I guess I propose craftable siphon cables.
Also, Kevin mentioned on IRC that items will get IDs, so hopefully that will lead to differentiating multiple batteries for example, and then we could have an alternate charge/ammo system, where for example multiple bullet types can be loaded, or where an empty battery can be retrieved from a flashlight. Then we could have slightly bigger utilities powered by 2 or 4 batteries.
Also, wireless electricity is already possible, it just has huge losses over range. A pair of vehicle components/machine mods could be created, for receiver and sender, and then it would also have some basic information transfer that would make it work and whatever. Either way, that wouldn’t be a lot of work above the previous challenges. You probably know more about them than I do.
So eh, what else is there. You need a proper electric generator to make an actual generator, an alternator doesn’t have nearly enough power output. Those are makeable manually, but rather complex. Let’s just say you could somehow transmute N alternators into one.
Also, thinking about it, it would make some sense if you could build appliances in a similar way to the one in which you can build vehicles, just not identical. Say, attach heating/freezing elements to (a) container(s), and a temperature regulator, build a fridge/oven, attach a large LCD display to electronics and some CPUs, make a laptop. Also, if you add item IDs, you could make flash drives/devices with actual storage, that would mean you could put lots of stuff. Honestly I’m just saying whatever at this point so I will finish writing and all that. Meh.