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All Series Hybrid EVs’ need a separate 12/48V accessory battery to provide “Limp Home” capability in the event that the power train battery died. It is needed to turn-over the ICE and power its electronics during start-up with a dead power train battery. It would also provide power for lower voltage accessories. Attached is a simulation of the performance in this mode.
The Volt motor has a peak power capability of 209 hp (latest web info), but in the "limp home" mode this is limited by the generator to 71 hp (53 kW). It is rumored (http://blogs.motortrend.com/6259238...our-cylinders-to-be-built-in-flint/index.html) that it will be powered by a 1.4L 4 cylinder non-turbo engine (estimated output of 88 kW/120 hp and torque of 175 Nm).
The simulation simply substitutes the 71 hp generator output for the Volt’s max motor power. The nominal peak torque is used for the “Limp Home”, because for most of the operating range in this mode (i.e. above 10 mph), power and not peak torque determines performance. (See the Torque/Power curves below.) Relatively speaking, the overall effect of the “Limp Home” mode is that the reduced power starves the motor torque when above 10 mph.
The time to 60 mph is 27 secs, the quarter mile time is 23 secs, and the max speed (first gear) is 80 mph. I defined the max speed as the speed at the end of 1 minute at maximum acceleration. I used 1 minute because it is a convenient round number and I don't think you can realistically keep the road surface, grade, straight direction, and banking and wind conditions constant for any longer period of time than about 60 seconds at high speed.
This simulation is based on the parameters and methodology given in posts: http://gm-volt.com/forum/showthread.php?t=719 and http://www.gm-volt.com/forum/showthread.php?t=459.
The Volt motor has a peak power capability of 209 hp (latest web info), but in the "limp home" mode this is limited by the generator to 71 hp (53 kW). It is rumored (http://blogs.motortrend.com/6259238...our-cylinders-to-be-built-in-flint/index.html) that it will be powered by a 1.4L 4 cylinder non-turbo engine (estimated output of 88 kW/120 hp and torque of 175 Nm).
The simulation simply substitutes the 71 hp generator output for the Volt’s max motor power. The nominal peak torque is used for the “Limp Home”, because for most of the operating range in this mode (i.e. above 10 mph), power and not peak torque determines performance. (See the Torque/Power curves below.) Relatively speaking, the overall effect of the “Limp Home” mode is that the reduced power starves the motor torque when above 10 mph.
The time to 60 mph is 27 secs, the quarter mile time is 23 secs, and the max speed (first gear) is 80 mph. I defined the max speed as the speed at the end of 1 minute at maximum acceleration. I used 1 minute because it is a convenient round number and I don't think you can realistically keep the road surface, grade, straight direction, and banking and wind conditions constant for any longer period of time than about 60 seconds at high speed.
This simulation is based on the parameters and methodology given in posts: http://gm-volt.com/forum/showthread.php?t=719 and http://www.gm-volt.com/forum/showthread.php?t=459.
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