California proposes DC metering standards for fast chargers, companies ask for more time

There is a proposal on the table in California that has to do with setting standards for energy metering on DC fast charging stations. Basically, the state is looking to enact regulations on EV charging similar to those that already exist for gasoline sales – gas pumps are regularly certified to ensure that when you pay for a gallon of gasoline, that’s what the pump dispenses, within a small margin of error.

While this may seem like a no-brainer for DC fast charging, industry stakeholders have been quick to speak up about the details of the proposal – mainly asking for more time to iron out the exact details of DC metering.

(This is one of a three-part report on new regulations that some argue could hold back EV charging development, originally published in Charged Issue 42 – March/April 2019.)

The California Department of Food and Agriculture has proposed amendments to Code of the National Institute of Standards and Technology (NIST) Handbook 44, Specifications, Tolerances, and other Technical Requirements for Weighing and Measuring Devices. California is the first state to take this spec and push for it as an actual requirement. Regulators are looking to have the metering feature on all new DC fast chargers, and also retrofitted on existing public hardware, by January 1st, 2020.

According to some in the charging industry, meeting this requirement is unlikely in the time frame allotted because of a lack of commercially viable technical solutions that achieve the proposed spec. There is additional concern about the high costs of retrofitting existing chargers, even if such high-accuracy meters were available.

Of course, all of the DC charging equipment in question already has some sort of a metering capability designed by the manufacturers. However, they are not all designed to the same spec, calibrated in the exact same way, or certifiable by outside agencies.

The biggest hurdle is that there is no robust market for this kind of DC metering technology in other industries. On the other hand, AC metering hardware provides an example of a mature market with plenty of competition. AC meters are found not only at every home and business that’s connected to the grid, but also on distribution transformers. As a result, there are a lot of different suppliers and competition for AC metering globally, so the cost is low and the technology is standardized. DC charging stakeholders are arguing that this is not the case for DC metering.

There is also an open question about the amount of accuracy needed for DC fast charging. Does it need to be highly accurate across the whole range of current levels, even if that’s cost-prohibitive?   

More time

Fortunately, according to charging industry stakeholders we spoke to, the regulators are open to feedback. The California Department of Food and Agriculture is now in the process of considering public comments, soliciting feedback from stakeholders and reaching out individually to discuss the impact of the proposed changes. The next step will be to release a revision, followed by another commenting period.

A similar regulation has been proposed in Germany [Anwendungsregel VDE-AR-E 2418-3-100], and authorities received over 900 comments from industry leaders.

While most agree that DC metering devices will have value in the long run, charging stakeholders are mostly concerned with the currently proposed timeframe in which they will be required. They believe that more time will allow for a consensus to be reached on the levels of accuracy required and that, with sufficient time before the new regulation kicks in, other businesses will enter the new market for DC metering that the regulation will create, offering a competitive marketplace with multiple sources to procure from.


This article appeared in Charged Issue 42 – March/April 2019 – Subscribe now.



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  • jstack6

    This is very important and needed in all states. In Arizona thy bill by time and a poor EVSE output is taking money unfairly from users. It’s very expensive and gets even more expensive as the car slows down the charge after 60 ot 70% . There is no regulation at all.

  • Dan Cizmarov

    I got similar problems in Canada..DC fast chargers varying charges…We got Mitsubishi I miev short range and small battery pack .Problem is charge per minute/hourly ..if I start charging at 20 % dod to 80% first 15 minutes allows max speed then Bms must slow it down as it approaches >50% after hits 60% slow down lots ..end of charge up to 80% it’s like l2. Time is forever lol ..half hour plus. Point is kw per hour injected is peanuts about 9kw aprox. Money charge is to much for given range in comparison to gasoline prices and never mind about how little electricity was injected.
    I understand if bigger pack is involved pretty much same money charge for double range or more .We are stuck mostly with home charging no longer affordable with DC charging. I hope regulators can fig how to implement this charge per kw dependent on battery pack size .Its like filling 3cyl car but paying 3 times more for fuel then guy with v8.Why guy with v8 if it fills more gas paying 3 times less per gallon of fuel .Very frustrating thing . Any one cross border got similar issues ?

  • SJC

    I would not make this a high priority, mandates early on can stifle innovation.

  • fiddlesteven .

    VW’s electrify America charges by the min, it’s more expensive than gas, and it gets even more expensive as the car slows down the charge after 70 or 80%. The smaller the car’s battery, the more expensive it gets because a small battery car needs a complete charge to get enough range. Where it isn’t necessary to charge to the point where the charge rate slows down with a larger battery. So everyone with an older EV will find it less costly to drive a gas car longer distances. If we want lower income people to drive electric, it won’t happen if we allow Electrify America to price gouge drivers of older cars with small batteries. To be fair, the charge needs to be by the kWh. Not by the Minute. We need to get a bill in the Oregon Legislature banning charge by the min rip offs.