Prius v, starter Motor question

The traction battery uses MG1 to start the gasoline engine. There is no separate starter motor.

The computer protects the traction battery, and won't let it drain down to dangerously low levels in stalled traffic or anything like that. If you had the gas engine running recently, the traction battery should have enough charge left for numerous starting attempts.

 

a toyota battery from a dealer would be all new. however, yours is not exhibitng any signs of danger.

all prius drain to two bars when sitting in traffic, the software is programmed that way.

if it starts swinging wildly from high to low and back, continually during normal driving, that's a sign of trouble

 

I should clarify that your 12V battery can get drained too low to start, which for the 12V systems means booting up the ECUs and pressurizing the brake accumulator, but not cranking the gas engine. A drained 12V battery doesn't mean a drained traction battery.

When stuck in traffic, as Bisco said, when the traction battery gets down to 2 bars, the ICE is forced on to charge back up to 3 bars. Lather, rinse, repeat until the fuel tank is empty. That 2 bars should have enough margin to crank the ICE quite a few times.