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Comment 7 for Advanced Clean Cars II Rulemaking (accii-comments-w3-ws) - 3rd Workshop.
First Name: Michael
Last Name: Nicholas
Email Address: mnicholas@hotmail.com
Affiliation:
Subject: Minimum onboard charger and convenience cord standards
Comment:
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.
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Date and Time Comment Was Submitted: 2021-08-23 14:46:44
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