Right now generators discharge extremely slowly (500kw each at base quality). Any chance this could be changed to be demand-dependent? They are batteries, after all.

Do you have a specific upper limit in mind? In Factorio it's the generator that is limited, not the battery.

I would adjust the base rate to around 1-1.5mw discharge rate if it had to be fixed, to make it a bit more viable. My general hope is to be able to run a Fulgora base without needing hundreds of generators.

I went a different route and added new batteries, chargers and generators which are available via Fulgora.

Even the fulgora chargers/dischargers seem a bit limited compared to accumulators, since they require constant replenishment of new batteries to stay functional.

Accumulators permanently add capacity and rate to the grid (300kW rate, 5MJ capacity at normal, or 750kW/30MJ at legendary). Normal dischargers add 500kW per 2 structures (charger/discharger), and require logistics (belts, inserters) as well as a few new batteries once in a while, so are significantly inferior as long as there is no need for highly assymetrical charge/discharge loads (eg. very short but bright day, very long night). Fulgora chargers reach 2 MW per structure, so assuming (incl. belt/inserters) 16 tiles per charger/discharger block (which seems close to the theoretical minimum, given that you need to deliver new empty batteries), are only slightly better than accumulators (125kW/tile vs 75kW/tile) (assuming zero footprint for the replacement battery manufacturing).

Maybe you could add structures with 5MW per structure, but slightly higher battery destruction rates?

Chargers and dischargers do improve with quality. A charger is faster and a discharger already has 5MW maximum output at legendary quality.

It should be noted that charged batteries stored in chests have a far higher storage density per tile than accumulators. So the area footprint to use them could also be viewed as a trade-off.

Both of these setups have 20MW throughput. The belt can easily hold 15GJ of stored energy. The accumulators can't hold even 1GJ.

And just in case you haven't noticed: There's a startup setting to disable battery maintenance if you feel it's too much of a burden.

I don't mind the battery maintenance, but wished batteries would provide some actual use beyond what accumulators provide. I find high quality accumulators already have sufficient capacity per throughput for my needs, and I don't really see a reason to use them over nuclear power in space either (for peak loads and with sufficient steam storage, only turbines matter, and they give 5.8MW per 3x5 area - generators at best give 4MW per 2x7 area, and have significantly worse energy capacity per rocket (25GJ for holmium, vs 80GJ for uranium fuel cells) and especially per stack (1GJ for holmium batteries, 400GJ for FCs).
The high storage density might matter for planets with very long day/night cycles or very asymmetric charge/discharge times, but I haven't found any use case so far where it isn't more convenient to just use nuclear power plants instead.

Another aspect is TPS cost - accumulators shouldn't cost any TPS, while many small generators and battery chargers do add up, especially once you add some level of circuit control...

Hm, I think I haven't looked at item weights at all, yet.

Batteries competing with nuclear fuel on energy density would be extremely unrealistic though, but a high (discharge) power density (output current per tile) would still make them useful as a backup power source for eg. platforms...

Does look competitive to me. And that's not considering that you can't really fly in 500° steam.

One way to solve your gripe would be to offer settings for the performance of the chargers/dischargers. But it's already tricky to juggle these for K2, SA and SE.

As for other uses: They do work pretty well as re-usable train fuel. That's what I initially made them for.

Adding a performance multiplier setting was easier than I thought.