Specifically it's 7kWh minimum in addition to all of the other sourcing and assembly requirements. In practice there haven't been any PHEVs with less, the smallest PHEV battery so far in the US is 8kWh in a Ferrari. It'll be interesting to see if more small battery PHEVs come out trying to target HEV price points with the tax credit. It would still be a huge jump up from standard hybrids which as far as I'm aware are rarely more than 1.5kWh.

kWh makes sense if your goal is to stimulate US battery production but I really wish there were an all-electric range requirement, A hypothetical 6.8kWh Prius Prime would get more range that the 21kWh Wrangler 4xe.

https://www.irs.gov/credits-deductions/credits-for-new-clean...