Does regenerative braking trip the brake lights?

Absolutely!!

 

If you've got your foot on the brake pedal, then the brake lights are on. This holds true whether the braking is friction or regenerative, and whether the car is moving or parked - as long as it's on.

 

What hyo said. I'm not really sure I understand the question. If you take your foot off the gas, you will be causing some mild regen. The brake lights are not lit. If you press the brake pedal, then you will blend regen and friction brakes, and the brake lights will of course be on.

Recall that any manual trans car can down-shift, and thus slow somewhat rapidly without the brake lights on. It is not illegal to slow down without brake lights. On my Rav4EV, I can choose from two levels of regen without using my brakes. All without the brake lights on.

Yes headlights will impact your mileage. Mileage will be impacted during the day and at night. It won't be much, however. The added draw is insignificant compared to the power needed to shove the car down the freeway. If you're worried about the mileage, drive slower.

 

Well, they're supposed to be on. A few of us have found the need to adjust the brake light switch. See this for more.

The headlights draw about 2 amps. As Darell says, the effect for most will be insignificant.

 

I'm not sure it does!
First level of regen is when you take your foot of the accelerator/gas pedal i.e. no pedals pressed to give the same feel as engine braking in a normal car

Second level of regen is when you press the brake pedal
the brake pads apply as a next level
sometime inbetween the brake lights come on

I cant tell if the switch on the pedal is used to start the second level of regen and light the brake lights
or whether the brake lights activate seperately, say with a pressure switch in the brake fluid

 

Paraphrasing what has already been said, the brake lights come on when you press the brake pedal. What the Prius does with that control input will vary, but the lights will always come on, unless something is broken.

As for slowing down without brake lights, there are several options: 1) Shift into N and coast, 2) Feather the gas pedal and glide, 3) Lift your foot from the gas which causes a small amount of regenerative braking, 4) Shift into B which causes engine braking, and 5) Hit something solid, like a tree or bridge abutment.

Of the five options above, #5 is the most effective.

Tom

 

The brake lights are operated by a mechanical switch on the brake pedal arm. You -can- have brakes without lights depending on the adjustment of this switch. Test it while stopped and backed close to a wall (so you can see the lights illuminate the wall). Regen is tripped by the braking computer, which uses brake pedal application rate and force to decide if regen will be used and how much to use. i.e. - if you slam on the brakes (high application rate) you get NO regen. As stated above you do get "engine braking simulation" regen as soon as you release the accellerator pedal.

A bit of correction on the headlamp draw.
Halogen headlamps are 55W each low beam and 60W each high beam. So that's 110W at 13.8V = 8 Amp draw low beam and 120W at 13.8V = 9 Amp draw high beam. I've measured more (5-6 Amps low and 6-7 Amps high for each bulb). DRLs (Canada) draw about 4-5 Amp (they are in series I believe).
HIDs draw about half what halogens do I'm told, but I haven't measured them.
At any rate, as 1 HP is about 750W, and it takes 10-15 HP to propel you down the road at speed, it's not going to have a big effect on mileage. Perhaps 1-3%.

 

tom1l21

Others before me have already answered your question about the brake lights, but I'm here now about your headlights being on 24/7.

You have a pkg #5 which has HID headlights that have been a big problem for Prius owners [look at the long threads of complaints---but look at post #436 to see that there may be help on the way in the form of a recall (the link will be at the end of this paragraph)], but the good news for you is that your 2005 uses the D2R bulbs (instead of the D4R bulbs which have been the troublesome ones on the 2006 & newer Priuses).

http://priuschat.com/forums/care-maintenance-troubleshooting/34584-headlight-problem-44.html

Regardless, I don't like using mine in the daylight to reduce their life when the bulbs are so expensive & usually require paying labor for the dealer to remove the bumper to replace the bulbs. I just use mine at night & when state law requires them in the rain. If you want daytime running lights, there's a couple of threads here about converting your foglights to serve that function just try doing a search. If you can't find those threads, just let us know & somebody should be able to give you a link if you're interested in doing that modification.

Ken (in Bolton,Ct)

 

I thought it is pure regen if above 7 MPH as long as it is not a hard brake?

 

I'm going to pull a "Roger Clemens" here: I mis-remembered. :redface: I just pulled up some of my old test files where I noted the approximate current flow at 1 amp. But I should have been more clear that that's the draw from the high-voltage battery, as observed from "before" and "after" readings on CAN-View when the headlight switch is activated. So that's consistent with the 55W per bulb figure.

On the subject of the brake light switch, I adjusted mine so the lights activate with minimal brake pressure and before braking actually begins (again as observed from current flow on CAN-View). I use this frequently when I want to signal to those who are close behind me that I'm decelerating (gliding or regenerative coasting) without actually braking.

 

If the regeneration battery limit is the same as the propulsion battery limit, then at higher speeds even moderate braking is physically impossible in pure regeneration mode. Friction is required in all but the lightest braking. At lower speeds, progressively stronger braking becomes possible.

A quick calculation for a fully loaded 2010 Prius stopping in hypothetically pure lossless regeneration mode, with progressively stronger braking at lower speeds, finds a 60-0 stopping distance of just over 1000 feet. For a constant g force stop, the distance would be over 2000 feet.

While better than pure friction braking, a lot of energy is still thrown away as friction during "normal" braking.

 

With your foot off the brake, the brake light does not light, assuming correct adjustment.

A minor terminology issue: Most of us limit the term "regenerative braking" to when brake pedal pressure is applied, as distinguished from regenerative coasting.

 

I have the HIDs on my 2009. Instead of keeping them on in the daytime, I keep just the parking lights on. This provides some visibility from the front and rear. Although the front parking lights/running lights are not overly bright, they are still visible, especially on overcast days.

They will shut off when you shut off the car, and will turn back on when the car is in Ready mode.

 

Do be aware however, the lights only go off if/when you open the -drivers side- door. If you exit from the passenger side they will stay on, putting your 12V battery in danger.

 

Thanks for the warning, David, although I've never actually climbed out of the passenger side when exiting the vehicle. Still good to know, however.

Also, if you have the HIDs on, turn the car to Off, and the turn the lights to the Parking Lights on setting, the lights will not turn off when you exit the driver's side door.

I try to always check when I walk away from the car, just in case I mistakenly left them on.

I also carry one of those combination DC tire pumps/battery boosters. Really funny that I got it for the Prius, but I've only had to use it for my Chevy van! Mine is made by Black & Decker, and it works really well.

 

Hey, yardman 49,

I don't think David Beale meant that he (or anybody else) would climb from the driver's seat over the console to get out the passenger door. But what we can conceive might happen is that a slow-to-move passenger may delay opening his door to get out until AFTER the driver has already exited & closed his door. That would then turn the lights back on & leave them on to run down the little 12V battery (if the driver has left the headlight switch in the "on" position).

Ken (in Bolton,Ct)

 

Hello Ken:

I don't think that would turn the headlights back on. But I'll try it to verify when I get a chance. Even the driver's door won't turn the headlights back "on" if they have already gone off. Just the interior lights go "on" when the doors are opened (assuming the dome switches are set appropriately, of course).