10-07-2018 04:06 PM - edited 10-07-2018 04:09 PM
I've discovered a good while back that Lenovo has decided to allow the internal battery to discharge first on ThinkPads with the bridge battery system depending on which battery has a lower wear level. This has been discussed multiple times such as in the following links:
Lenovo has not responded to the multitude of customer requests and complaints in regards to this issue.
The other day my internal battery was discharging first. To my surprise, the battery guage got stuck at 7% for a long time so I knew something was wrong. So I reboot my system, and when the computer rebooted, I got an error message saying that the internal battery could not be detected. When I got home I charged the battery and discovered that the internal battery had drained all the way to 0%... Instead of switching to the external battery while leaving some battery left on the internal battery, the system allows the internal battery to drain completely, thus rendering the whole hot swappable/bridge battery feature useless (not to mention that this is terrible for the lifespan of the battery).
Seriously if you are thinking of buying the T480... pass and look elsewhere until they fix this discharging sequence. One of the top reasons I chose the T480 over other laptops was the bridge battery system, but if I had known that Lenovo chose to make it behave this way, I would have easily passed and chosen a different machine like the T480s or X1 Carbon so I wouldn't have to deal with the hassle of having a 2 battery system that chooses to discharge in an illogical sequence.