What is the chemistry of the batteries? May 21, 2020 01:29 Updated The battery are Lithium Ion batteries. There are two that come with the Sutro. Related articles What chemical parameters does Sutro test for? How long does the Sutro Test Cartridge last? Can I connect Sutro to other smart devices in my home? Does Sutro work with Salt Water Systems? Replacing a Cartridge and Battery Comments 0 comments Article is closed for comments.