Yes. Different chemistries entirely. A 3 yr warranty is typical and reasonable, for the 12v pb-acid battery located under the cargo area in the back of the PHEV. This is a battery that an owner can easily change on his own and buy at a walmart or whatever. The 12v lithium-ion poly battery of the HEV is packaged inside the traction battery case. I don't think the left hand was talking to the right at Hyundai when they wrote the warranty book for the HEV, especially since the identical 12v battery of the Ioniq is warrantied 10 years. The short warranty for the HEV invites Magnuson-Moss problems for Hyundai. Let's say the 12v battery in the HEV goes bad after 4 years. Under Magnuson-Moss, the car owner has the right to repair it himself or have a third party (non-dealer) do the repair without voiding any warranties. The traction battery case has to be opened to replace the 12v. Now, according to the warranty manual, the traction battery warranty is void because non-authorized people opened the case...