15-02-2013, 04:03 PM
Lessons Learned, Why are Fuses and Solenoid Disconnects So Important in EV’s?
[attachment=51083]
Overview
Gasoline driven vehicles have a century worth of
design evolution, from increasing performance to
meeting safety requirements. Electric vehicles are still,
relatively speaking, a new and infant market. Many
lessons are learned when rebuilding EV cars such as
wrong motor & controller combination, old or worn
motor brushes, stock wiring used with a 600 amp
controller, or a hunting buggy plowing through the bog
with stock gearing and large tires.
In electric vehicles, when we change design
parameters – we can stress other components. It’s like
putting a Chevy 454 in a Chevy Nova with a stock
transmission, high way gearing inside a weak 10 bolt
rear axle. Of course it will work – for a while…and then
“an event” occurs and something fails or lets loose.
Electric vehicles provide “motive power” in a
different way; they utilize a large battery pack as the
source of power (fuel), controlled by a DC motor
controller to modulate power (carburetor) based on
throttle input, and an electric traction motor (engine).
Detailed Discussion:
Lets discuss the details of each component for the
fuse, contactor, pre-charge resistor, and coil diode. We
will also briefly discuss wiring, batteries, and
terminations.
Fuses:
Any application where there is a battery pack, a fuse
must be installed. Anyone who has dropped a wrench
on battery terminals or accidentally touched the
positive and negative battery wires together knows the
importance of a fuse. Batteries store a lot of energy
and in the case of a direct short the results can be
pretty dramatic.
A fuse will open the battery circuit and prevent any
serious damage from occurring. Without a fuse, the
shorted battery string will continue to supply power
until a battery explodes or one of the connections
melts. By then it is too late and the vehicle will
probably have burned to the ground.
[attachment=51083]
Overview
Gasoline driven vehicles have a century worth of
design evolution, from increasing performance to
meeting safety requirements. Electric vehicles are still,
relatively speaking, a new and infant market. Many
lessons are learned when rebuilding EV cars such as
wrong motor & controller combination, old or worn
motor brushes, stock wiring used with a 600 amp
controller, or a hunting buggy plowing through the bog
with stock gearing and large tires.
In electric vehicles, when we change design
parameters – we can stress other components. It’s like
putting a Chevy 454 in a Chevy Nova with a stock
transmission, high way gearing inside a weak 10 bolt
rear axle. Of course it will work – for a while…and then
“an event” occurs and something fails or lets loose.
Electric vehicles provide “motive power” in a
different way; they utilize a large battery pack as the
source of power (fuel), controlled by a DC motor
controller to modulate power (carburetor) based on
throttle input, and an electric traction motor (engine).
Detailed Discussion:
Lets discuss the details of each component for the
fuse, contactor, pre-charge resistor, and coil diode. We
will also briefly discuss wiring, batteries, and
terminations.
Fuses:
Any application where there is a battery pack, a fuse
must be installed. Anyone who has dropped a wrench
on battery terminals or accidentally touched the
positive and negative battery wires together knows the
importance of a fuse. Batteries store a lot of energy
and in the case of a direct short the results can be
pretty dramatic.
A fuse will open the battery circuit and prevent any
serious damage from occurring. Without a fuse, the
shorted battery string will continue to supply power
until a battery explodes or one of the connections
melts. By then it is too late and the vehicle will
probably have burned to the ground.