The protocol is somewhat standardized but the ec does expect certain batteries. The laptop side of the communication is actually open source, you can see how it talks to the battery and probably make a custom version that doesn’t get a panic attack when it gets dc on the battery connector with a non responsive battery.
From the ECs perspective, having power on the battery pins without the battery talking to it means something seriously went wrong with the battery (if something goes wrong in a laptop battery it usually permanently disconnects the power pins, if it dies and could not do that something went really wrong and that battery is probably not safe to use).
It may actually take different batteries, didn’t read that far into the ec code jet but power on the power pins without battery communication is not a normal state to be in, this hints at something in the battery being really wrong, and I’d be a bit concerned if it didn’t get at least a little offended at that and really concerned if it tried charging it.