Plausibility of ancient extraterrestrials

[Sicnoo0]

There is one specific document called Agastya Samhita that seems to have detailed instructions on how to build an electric battery, as well as how to use an electric battery to split water into its two constituent gasses, pranavaya and udanavaya. Would it have been difficult to correctly guess that there are 2 distinct elements that comprise water? I really can't get over the building a battery part. That seems like a clear sign of scientific knowledge

Then again, like Anomalocaris said, there were brilliant people in ancient times here and there.