Some EVs do not illuminate their brake lights when utilizing regenerative braking, Shopper Stories present in a latest take a look at.

Regenerative braking permits drivers to decelerate (and momentarily cost the battery) with out utilizing the brake pedal, which may additionally imply that it’s inconsistent with brake lights, CR present in a take a look at of EVs from Genesis, Hyundai, Kia, and Mercedes-Benz.

A part of the issue is that when counting on stronger regenerative braking, in any other case referred to as one-pedal driving, drivers typically maintain mild stress on the accelerator pedal to easy the transition between acceleration and deceleration, CR discovered. And a few EVs will not illuminate their brake lights except the motive force takes their foot fully off the accelerator.

2022 Kia EV6, crimson, and 2022 Hyundai Ioniq 5

Federal laws additionally do not cowl brake-light use with regenerative braking. As CR notes, Federal Motor Car Security Commonplace (FMVSS) quantity 108, which covers brake lights, states that they have to be activated upon utility of the service brakes (i.e. the friction brakes), however doesn’t require brake lights to be activated when the service brakes aren’t in use. It doesn’t prohibit use of brake lights when the automobile decelerates by different means, but it surely would not require that both.

CR first observed this challenge in 2014 with a BMW i3 take a look at automobile, but it surely cropped up once more throughout assessments of more moderen EVs. Testers discovered {that a} 2022 Hyundai Ioniq 5 may very well be dropped at a “near-complete cease” with out the brake lights turning on, so long as the motive force stored slight stress on the accelerator pedal.

Testers noticed the identical leads to EVs from different Hyundai-owned manufacturers, together with a 2023 Genesis GV60 and Electrified GV70, a 2022 Kia EV6, and a 2023 Kia Niro EV. Each the Ioniq 5 and Kia EV6 have comparable regenerative braking conduct—though they’re styled very otherwise. The Hyundai Ioniq 6 would not seem to have exhibited the identical conduct.

2023 Mercedes-Benz EQE 350+

Mercedes-Benz EQ fashions in Robust Recuperation mode (the very best degree of regeneration) exhibited even odder conduct. As velocity dropped to about 5 mph and the speed of deceleration decreased to offer a smoother cease, testers discovered that brake lights turned off, illuminating once more after about 15 seconds. A Mercedes spokesperson quoted within the CR report mentioned the brake lights in query complied with laws, noting that lights aren’t required whereas the automobile is stationary and the brake pedal is just not depressed.

Purposeful regenerative braking was first used again within the Sixties within the American Motors Amitron, however did not turn out to be generally used till hybrids and EVs turned mainstream. Automakers nonetheless have completely different views on regenerative braking, with some opting out of robust regen, underscoring that it’s much less environment friendly than coasting in some conditions and invitations uneven driving.

Tesla automobiles by no means had excessive regenerative braking earlier on, and the BMW i3 was the primary mannequin Inexperienced Automotive Stories encountered with very aggressive regen that meant you may drive lengthy distances with out touching the brake pedal. That strategy doubtless will not go away. Automakers have even thought of a future wherein friction pads is likely to be eradicated totally.