AssessorsJournalMagSpring2024 web - Flipbook - Page 19
Why did GM try so hard? In essence
the battery technology was not in
the right place, so in order to make
an effective vehicle all energy losses
had to be minimised. Hence, for quite
a while, the aerodynamic exterior
pro昀椀le was closely associated with
'hybrid drive', which in turn became
synonymous with ‘Prius’, much to the
frustration of Toyota.
The tell-tale of great engineering is
the ability to have very sophisticated
systems where everything is done for
a reason, which is apparently simple to
use and repair.
This is what we will explore.
Rate of change increasing
exponentially
The break-neck rate of change
across the electri昀椀cation subject is
due to manufacturers working hard
to minimise tax penalties, meet
production / import quotas, meet
ever-changing demands for reduced
or zero tail pipe emissions – and try
to make a pro昀椀t. The result is the
aftermarket and the collision repair
business is on the receiving end of this.
The upshot is a full-on mix of trends:
• Conversion of existing large
investment platforms to
electri昀椀cation, resulting in high
voltage systems being installed in all
sorts of unusual places.
• Creation of dedicated scalable large
investment platforms in parallel,
pushing cash 昀氀ow and pro昀椀tability to
the edge.
• Ever changing component upgrades
to achieve better performance in
current production vehicles – yes, that
includes the biggest, most expensive
single item especially on a BEV, the
battery, with no compatibility with
previous models.
From a very small evidence base, we
can already see a 2012 Nissan Leaf
is likely to need a complete battery
rebuild and revised cooling system
whereas a 2012 Tesla Model S will
be mostly intact – but can suffer from
catastrophic failure of motors, the
traction battery and even the power
controller. In other words, reliability
trends have not been this make / model
speci昀椀c since the 1970s.
www.iaea-online.org/news/the-assessor | SPRING 2024 | THE ASSESSORS JOURNAL
The elegance.
Due to parasitic losses from an
ever-growing number of 12V body
systems, the problem of battery
depletion after a few weeks has
become something of an epidemic
over the past two decades. Add to this
the 昀椀xation on electronically activated
door handles, and the apparently
random scattering of high voltage
system components, we have a perfect
mess.
Part of the solution is to allow the 12V
battery to draw from the high voltage
battery – if it has one – while the
vehicle is parked / stored. This idea is
now extended to allow the high voltage
battery to draw energy from the 12V
battery if required. In other words,
setting the drive system to ‘power
down’ via the instrument panel does
not mean high voltage isolation.
Toyota addressed this very issue,
starting with Prius 1. The 12V
battery was the master, so if it was
disconnected the high voltage battery
would be isolated. To add security,
a ‘service plug’ on the high voltage
battery system ensured isolation
could not be bypassed. Now, it could
well be advantageous to keep the
battery control module alive to permit
post impact system cooling. Even
so isolation of the high voltage pack
should be straight forwards to maximise
safety.
Perhaps it’s time to lobby for
standardisation of a ‘kill switch’
location, leaving engineers to manage
how that works, but ensuring the safety
of everyone who needs to work on
electri昀椀ed vehicles. Meanwhile, vehicle
speci昀椀c research has never been more
important.
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