Ok, so I have code P0A80 on my Prius C. So I dismantled the battery and checked the modules one by one. I tested each module by hooking it up to a light bulb that draws around 4amp. The trend I am seeing is the batteries would drain fast going from 8v to 7.2v. Ranging from 10 min to 4 min. Then from 7.2v, those modules that are still good would drain slower, like 10min going into 7v. However, as I tested a few spare batteries I got from a Prius Gen 3, it is the opposite. From 8v to 7.2v, it will take 20 min. But from 7.2v to 6.8v, it will drain faster like 8min. TLDR; Prius C batteries discharge slower when voltage is low. Prius Gen 3 batteries discharge slower when voltage is high. Is there something wrong with the spare Prius Gen 3 batteries I have? I have tested 2 modules and both have similar treand compared to 20 modules tested on Prius C Here is one example,
