A tale of two "Bidirectional Charging" Bills

An example of the transmutation of bills

The legislature process that creates and approves a California Bill allows amendments to the bills at multiple times. This means the bills can change a lot. I am not aware of any real limit on what qualifies as an “amendment”; I believe pretty much anything goes, except the bill number, and (maybe?) the author.

SB-233

SB-233 and SB-59 are two bills introduced by Senator Skinner. SB-233 started as a fairly ambitious bidirectional charging bill. The bill was amended significantly in September 2023 and it then went into hibernation. When it came back in April of this year, it had Assembly Majority Leader Aguiar-Curry as co-sponsor and it was an abortion rights bill. The bill was approved by both houses and it was quickly signed by Gov Newsom (see vote history).

The old SB-59

SB-59 started as a women’s health bill: back in December 2022 it was described as the Menstrual Product Accessability Act. As such it was last amended in January 2024 and then it passed the third reading in the Senate. The next step would have been on the Assembly, except that it didn’t move forward until earlier this month, when… it came back as a bidirectional charging bill! The latest version of SB-59 is, in a sense, the continuation of the old SB-233.

The new SB-59

The new SB-59 started in the Health committee because that is where the old SB-59 was but it was quickly redirected (see vote history) and it is now on the Utilities and Energy standing committee.

The “new” SB-59 is very short. After some stage setting and some definitions it has just two sections:

44269.1.

 The board may periodically update the definitions provided in Section 44269 to ensure that the definitions align with current technologies in bidirectional charging and account for ongoing innovation.

44269.2.

 (a) The board, in consultation with the commission and the Public Utilities Commission, may require any weight class of battery electric vehicle to be bidirectional-capable if it determines there is a sufficiently compelling beneficial bidirectional-capable use case to the battery electric vehicle operator and electrical grid.

(b) This section does not prohibit the board from crediting a manufacturer of a battery electric vehicle that voluntarily includes bidirectional capability for that battery electric vehicle weight class.

Since SB-59 changed (a lot) between the Senate and the Assembly version, it will have to go back to the first house (the Senate) to be voted again. Next year we may get a stronger version, but this version of SB-59 sets the stage and I hope it will get approved, and signed.

Why Bidirectional Charging?

The main driver for bidirectional charging is the price of the batteries. According to EnergySage the cost for installed stationary batteries in California is around $1,090/kWh. A Chevy Blazer EV has a 85kWh battery; price seems to be around $43K. Do the math!

The main use-case for these batteries is resilience as blackout support; this use-case is usually denoted as V2H - Vehicle to House. Blackout support uses roughly the same setup as that needed to use a generator to power a house. In another approach to resilience the car includes AC outlets that can be used to power appliances using extension cords. This is usually called V2L and it is equivalent to using a generator to provide electricity while camping.

The other term you will see is V2G, Vehicle to Grid. V2G is essentially V2H with some interconnect to the electrical utility. From the perspective of the car, V2G is the same as V2H. The most common setup reuses the interconnect from a Solar Panel installation, and the bidirectional discharge is subsumed into the Solar Panel output. Unlike with Solar Panels, the battery of the EV can be dispatched, so it could be part of a Virtual Power Plant (VPP) for emergencies… or for daily time-shifting.

Blackout and disaster recovery are very unfrequent events and are not likely to raise questions about the impact on the health of the batteries in the EVs. Load time-shifting - charging the battery when there is cheap renewable energy and discharging it later - is a daily activity and that raises the question of the impact on the life of the batteries. The new batteries can last for many years and many battery cycles; they will likely outlast the car itself (CATL announcement). Using these batteries for daily time-shifting would make sense but we will see what the car manufacturers decide.

Next Steps in Bidirectional Charging

The first UL-approved bidirectional charger was from dcbel. Ford, GM, others have bidirectional chargers focused on their own cars, but there are many chargers getting ready for next year, including well known names like Enphase, Emporia and Wallbox. UL certification tends to be a slow process and the switch to NACS/J3400 must have slowed it down further.

Pretty much all new EVs are bidirectional capable, the biggest exception are old Teslas: Model S, X, 3, and Y do not support bidirectional charging but the Cybertruck does. Even my 2021 ID.4 has the capability for it, though it is not enabled in the US (VW, we are waiting!)

Personally, I would not buy an EV in 2025 that does not have bidirectional charging.

SB-59, and future follow-ups should help solidify the adoption of bidirectional charging.