[2.0.15] Accumulator charge counted incorrectly when merging 2 connected networks

[abognasar6]

What did you do?

I merged 2 electric networks by placing a medium power pole.
(These 2 networks shared 4 accumulators before the merger.)

What happened?

In the accumulator charge graph of the Electric network info panel, the charge history shows an incorrect amount. An amount exceeding the maximum charge capacity of all accumulators.

2024-11-17_18h04_07.png (3.53 MiB) Viewed 382 times

It looks like the accumulators that were connected to both networks were counted twice.
(4*5=20MJ and 95-20=75MJ, which would be the correct amount.)

What did you expect to happen instead? It might be obvious to you, but do it anyway!

I would expect the accumulators that were connected to both networks to be counted only once.

Does it happen always, once, or sometimes?

Always

Reproduction steps

1. Load the attached save file.
2. Mine the medium power pole in the middle. (The one connecting the substation and the power pole with the accumulators.)
3. Open the Electric info tab of either network.
4. Replace the power pole to merge the networks.
5. Hover over the graph to see the incorrect amount.

Log file:

factorio-current.log

(8.28 KiB) Downloaded 12 times

Save file for easy reproduction:

test bug v2 20241117.zip

(3.45 MiB) Downloaded 13 times

[boskid]

Thanks for the report however if electric network statistics would be required to hold for each time point, which exact entities were in which specific networks just so this case could be correctly handled, it would be so much more data to update every tick that we would just remove statistics at all due to too high performance impact on the game. Its either 1/ blind statistics merge as of right now, 2/ completly discarding statistics of the smaller network or 3/ no statistics at all. Currently we are at 1/ and i am not seeing this to ever change to the point i am not considering this to be even a bug.