Comment Log Display

This comment is directed at two topics. First the proposed minimum
onboard charging speed standards for BEVs and PHEVs should be
increased. Second, the amperage that the convenience cord draws
could be selectable to allow better use of home electrical
circuits. 

These are two separate issues. It seems in the proposed ruling that
the same power minimums are applied to the onboard charger and the
convenience cord - 5.76kW, but they could be different to address
two different issues. The onboard charger should increase in power
to enable faster public charging and to encourage faster charging
to be installed. Whereas the convenience cord is most applicable to
residential charging where existing dryer plugs can be used, or
low-cost upgrades can be installed. In this case, circuits or
electrical panels may not be able to handle higher power than
5.76kW. Owners may have to buy additional convenience cords if
those supplied by the manufacturer are too high power. Simple
changes to the requirements are low cost and allow more flexibility
for charging to the first AND second owners.

First, some terminology for this comment. There are different
voltages, amperages and power and it gets confusing to write about.
The regulation is written in kW, but circuits are typically talked
about in amperages. For example, 5.76kW refers to 24 amps at 240V
with a 30 amp breaker. These are all relevant, but I'll use CAR
AMPS (80% of breaker capacity) since we are talking about the
interface between cars and infrastructure. Commercial voltage is
208V whereas home voltage is 120/240V. So, if I reference 24 amps
this is equivalent to 5.8kW (or really 5.76kW) in regulation
terminology. Here is a table to interchange between terms.

Breaker amps	Car Amps	Voltage		kW
15		12		120		1.4kW
15		12		208		2.5kW
15		12		240		2.8kW
20		16		208		3.3kW
20		16		240		3.8kW
30		24		208		5.0kW
30		24		240		5.8kW*^
40		32		208		6.6kW
40		32		240		7.7kW@
50		40		208		8.3kW
50		40		240		9.6kW
60		48		208		10.0kW
60		48		240		11.5kW+

*   Current proposed regulation
^   Suggested selectable amperage for convenience cord
@ Suggested minimum PHEV onboard charger standard
+  Suggested minimum BEV onboard charger standard

Onboard charger
Currently the suggested minimum onboard charger power is 24A. The
minimum for BEVs could be 48A. The minimum for PHEVs could be 32A.


The primary rationale for this is that it will increase the use and
effectiveness of public charging. Currently, the de-facto public
chargers are 32A. This is fine for many situations. However, this
speed is too slow to make plugging in worth it on short stops such
as for a one-hour lunch. At 6.6kW only about 20 miles would be
recovered. At 10kW, about 30 miles are recovered. Studies show that
each mile recovered during charging may increase the likelihood of
plugging in by 1.4% (https://escholarship.org/uc/item/9c28789j).
Comparing 18 miles recovered to 30 miles recovered, for one hour of
charging, the likelihood of plugging in increases by 17%.  From an
infrastructure perspective, two 48-amp chargers could theoretically
take the place of three 32-amp chargers as long as cars were
ideally plugged in. But any reduction in the number of chargers
depends on the cars being able to accept higher power.

The rationale for PHEVs is the same, but given a battery size for
the minimum 50 miles range in 2026, a 7.7kW minimum onboard charger
speed may be more feasible. Since BEVs can fast charge at speeds
greater than the proposed AC charging speed, this concern over
accepting higher power from the onboard charger should be less of
an issue.

By increasing minimum onboard charging speeds, meaningful range can
be added to a car at a greater variety of location types such as
grocery stores, restaurants, and other shopping where dwell time is
often less than an hour. This is especially important for those
with no home charging. By 2026, early adopters with home charging
will be less of the market than they are today. Increasingly,
renters and apartment dwellers with no home charging will be more
common. Fast charging can be expensive to install, and is not
necessary in many cases. But with low AC charging speeds, DC may be
the only rational choice given time constraints. Homeowners with
overnight charging may not typically need the faster onboard
charging speeds and won't choose it as an option at purchase.
However, this first-owner choice precludes the second owner from
being able to take advantage of higher charging speeds. The second
owner may be lower income and may rely on public charging more than
the first owner. We can design cars to be useful to all owners.


Faster EVSE are beginning to appear already, and cars with faster
charging ability are appearing as well, but only very slowly. Blink
is deploying 64A chargers at some fast-food restaurants for
example. In Europe more than half of all public chargers are
between 11kW and 22kW. 64A in the U.S. is about 11kW as noted
above. Many cars are built in Europe to take advantage of these
available power levels suggesting complying in the U.S. would not
be all that difficult. On the car side, Ford's f-150 lightning will
charge at 80A. The Ford Mach e can charge at 48A. A minimum
requirement for faster onboard AC charging speeds will amplify this
trend and encourage the installation faster public AC charging. The
additional cost on the car side is expected to be in the low 100s
of dollars (https://neo.ubs.com/shared/d1wkuDlEbYPjF/).

The current proposal for minimum charging speeds of 5.76kW will
limit the public charging options drivers can take advantage of and
limit the market for electric vehicles, especially for those with
no home charging. If cars can't accept a certain power widely,
public chargers with higher power won't be installed widely. Higher
AC charging speeds are appropriate in several location categories,
but if cars can't accept higher speeds, then cars will be the
bottleneck at these locations.


Convenience cord
On the other hand, power may be limited in residential situations.
A convenience cord with selectable amperage level will help those
with home charging get the most out of their situation without
buying an extra mobile charger. Currently, at least two
manufacturers supply 240V convenience cords, however, the
convenience cord is set to draw 32 amps. Many older homes and even
newer homes can only safely draw 24A through a dryer plug. For
these people, the supplied 32 amp cord is useless and a new
convenience cord must be purchased for hundreds of dollars. 

Many people will defeat the circuit protection by using a dongle
which allows a 32 amp plug to plug into a 24 amp circuit causing
potential fire danger. One manufacturer however allows selectable
amperage via the car and via the convenience cord. Via the car,
users can select any safe amperage on screen. And the convenience
cord has dongles for different plug shapes (e.g. a 24 amp plug
shape versus 32 amp plug shape). Each dongle communicates with the
convenience cord indicating the safe amperage, and the convenience
cord relays that information to the car. 

In order to avoid hazardous situations and allow owners to take
advantage of available amperage, charging amperage should allowed
to not exceed 24 amps using 4 possible compliance paths

1.	Provide a single-speed convenience charger that signals to the
car to not draw more than 24 amps
2.	Provide a multi-speed convenience cord with selectable amperage
via buttons on the convenience cord
3.	Provide dongles that indicate safe charging amperage to the cord
and car
4.	Provide user selectable amperage via a car interface that allows
the car to set default amperage less than the amperage signaled by
the charger.

Options 3 and 4 are probably the best and safest options. This
allows convenience cords to be 32 or even 40 amps while allowing
the possibility to reduce amperage as needed.