Prius C Alarm P0A80

Old post, but...

P0A80 is set when the battery block voltage has a difference of 1.2V from highest to lowest. It's a two-trip fault, meaning it must happen two times within a set time. It will set a pending code, and then wait 10 minutes before allowing the code to set again. After that ten minutes, if the voltage variation happens again, it will set a current code, and turn on the lights.

If the code is reset, it will function as normal again, but will come back pretty quick.

The battery blocks are hooked together, and therefore always balance themselves, so you usually won't see a difference by just looking at a scan tool. It's only when there is current, and the battery is being charged or discharged, that the resistance difference between blocks will be apparent, and there will be variations in voltage from block to block.

It's usually worse when the battery is in a low state of charge, like using full battery power to accelerate, all the way until the ICE turns on. In a low state of charge (30%), when the ICE is engaged, this requires a large kick from the battery, and a bad block will quickly become apparent.

When P0A80 is set, we go straight to the DTC freeze frame data, and you'll see one block will be much lower than the others. This alone is confirmation that the problem is in fact the battery, and not a sensor or controller.

 

did you use any kind of reading device like the techstream to check the battery block voltages ??