I placed the CTEK multi US 7002 battery charger on a regular lead acid 12 volt car battery. I made sure the leads were correctly connected to the proper terminals on the battery. I set the CTEK to "normal" mode. The battery charger showed an error code 0 (!).

I then took an older Sears car battery charger and attached it to the same lead acid battery. The charger shows the battery about half charged and it appears to be charging the battery normally.

So, I took the CTEK to another car I have that has an AGM battery. I set the CTEK to "snowflake" mode. It is charging the AGM battery perfectly fine.

What gives?