2010 LX570 stalled while approaching a stop light.

What is your question?

The battery indicator light came on. There was no electrical power. The car would not start. I jump started the car to drive it home. As I drove and stopped at stop signs and the RPMs dropped, the electrical system seemed to be on the verge of shutting down. If I kept the RPMs high, the electrical system seemed stable. The battery is 3.5 years old.

What makes this problem better or worse?

Low RPMs

How long has your 2010 Lexus LX570 had this problem?

3 hours