[Quark and Lepton]

There's always something going on.
It's like a groundhog. If you see charge, assist, or auto-stop, then you've got a bit longer to live.

You could try this:

 

[Quark and Lepton]

Thanks for the response. As I wrote in the original post, it is not a battery issue (the thing is brand new). So, your suggestion won't help.

Another thing I've noticed is that the time it takes for the charging system to kick in depends on the outside temperature. If it's cold (~50 or below), it takes a few minutes for the charging system to kick in. If it's warm (~50 or above), it only takes a minute.

I don't know if this is a common issue with these hybrids or if it's an indication that the charging system might be wonky and in need of repair.

I had something similar. Have you tested it with a different 12 V?

The charging system is certainly capable of issues, but the charging system is more likely to be limited by the capacity of the IMA battery sticks (where the charge is going) and the 12 V battery.

If the IMA battery sticks are old they may not want to accept charge, drain excessively, and more.

Best wishes.