THERMAL MANAGEMENT
Unfortunately,
these measures
will lead to
additional cost as well
as increased NVH.”
Research at Cosworth,
meanwhile, showed that fast charging reduces
both lifespan and energy retention, and that
these problems are compounded by inadequate
cooling. Temperatures above 80°C (176°F) can
cause physical damage to the microporous
separators between the electrodes, as well as
the active materials, Freedman says. New
separator materials, designed to melt and close
the pores to interrupt the fl ow of ions,
could help shut down the battery
before thermal runaway begins.
Better design
The bigger challenge is corner
cases, according to Giles
Muddell, chief engineer of
control systems at Prodrive.
The rise of more advanced
manufacturing processes are
delivering more consistent cell
performance, he says, but it’s
not possible to monitor every
cell individually.
“For example, it is di cult to predict all the
cell temperatures when a car, after being
driven in arctic conditions and with ice packed
around part of the battery, gets plugged into
a fast charger. Such a failure to predict cell
temperatures can result in a cell overheat
situation,” he says.
56 // January 2020 // www.electrichybridvehicletechnology.com
“However, as the EV design community
becomes more and more familiar with such
problems, we are able to specify design rules
that either design the problems out of a pack,
and/or place sensors in the correct positions
to be able to detect the onset of the problem
and then mitigate it.”
Hintennach agrees. “Our former battery
management systems were a lot simpler than
today’s. They were even more restrictive,
because the less you know, the more careful
you have to be. The better you understand it,
the better you can play with the parameters
and still have the highest safety,” he says. “We
are handling hundreds of volts, but EVs are
considered to be very safe.”
7. The coolant line and
cell monitoring unit
contributes to keeping
Mercedes’ battery system
at optimal temperatures
8. Cell analysis provides
engineers insight into
how to maximize battery
performance and
manufacturing methods
9. Ionity’s high power
charging network has
also had to solve thermal
management challenges
7
8
9
/www.electrichybridvehicletechnology.com