[chuck960]

Hi guys!
I have an 06 HH 4wd with 18000 miles and I love this vehicle. I live in a snow belt off Lake Erie so I'm in the snow allot and it drives like the roads are dry.
As you know when you step lightly on the brake pedal the power indicator shows you the amount of battery charging in kwh, you feel the car slowing and you hear the motor/generators whine.
About 10% of the time when I step on the brake the car brakes on mechanical brakes only. About 10% of the time when I step on the brake the system works normally. Sometimes I get some lesser amount of regen ( the battery is charging slightly ) Sometimes it works ok for a few seconds and then drops out. When it drops out it feels like you loose your brakes and you have to push harder on the pedal.
My fuel economy is down under 18 mpg city this winter. I was supposed to get 29
The problem is getting worse over time. I'm guessing it is the battery but how to get them to investegate.
The dealer keeps telling me that there are no codes. I don't think they have enough experience with this system.
If the engine was running on 3 cylinders service would know instantly. If the recharging system is working at 50% there's a problem.
Anyone else notice this. Are you keeping your eye on it?
Also I would add that this car never runs on battery with the engine off. Even in parking lots if the car is moving the engine is on.

 

[Tideland Prius]

ehh.... ok.

So next time, brake and then shift to N. Do you feel a sudden grab? If so, you were regenerating before.

 

[don r]

This behavior doesn't seem unusual especially if your drive to work is 30 minutes or less and the temperatures are averaging 40 degrees or below.

The Hybrid system goes into hybrid-nation in the winter time due to the extended time required to warm up the vehicle, especally as the average temperatures dip below 30 degrees F

The engine runs a lot to keep the vehicle warm, and the hybrid system has a tendency to keep the battery charge close to max with all the engine running time. If the charge level on the multifunction display is a bar below the top, the braking system tends to disengage the regeneration in very cold weather a few seconds after applying the brake to apparently prevent battery overcharge.

As a test, if you turn on all electrical accessories (rear defroster, lights, heated seats, radio, etc) and let the battery drain down a bit with the engine warmed up and cycled off, the full time regeneration returns when braking.

Also, in very cold weather after the engine is at operating temperature (180 degrees) after 30 minutes of driving, the hybrid system does not let you drive at slow speeds with the engine under electric motor power alone. Even the slightest load kicks in the engine at speeds of 20-40 mph. I have not tried this after a full hour of driving and those results may be different.

I have 15K on my '06 4WD and have averaged 27.5 MPG over 44 tank refills.

Ambient temperature has a great effect on fuel efficiency with a hybrid. My experience using weather service temperature data averaged over each tank refill duration is below:

< 32 degrees F: 23.39 MPG (over 10 tanks)
> 32 degrees F: 27.79 MPG (over 34 tanks)
> 50 degrees F: 29.43 MPG (over 20 tanks)
> 60 degrees F: 30.24 MPG (over 15 tanks)

 

[chuck960]

I just got home from Key West. Thanks for replying don r.
I rented a Prius for the week and got 48.7 mpg over 405 miles. I like that It has leg room and a back up camera.
This has been going on since last winter. This summer when it was 80 there were times when the system would brake with mechanical brakes only. It's getting worse but I don't see the weather as being the trouble.
I'll try the thing with the accessories on to run down the battery however it act's up with the battery charge bars (display) showing almost full or almost discharged.
My milage the last two months has been 17. Overall is 23.4
And yes I do live close to work but I have kept records over the 18,000 miles and my Excel spread sheet shows a downward trend.

 

[wolfcal]

i noticed that different gas station make a huge diffence in mpg...i live in ca up in the sierras and with 36k on my 06 i average 25-26 mpg with cheveron gas. when my wife slips up and puts in our local shell gas, the car almost immediately drops to 19-20mpg, for the 5cents per gallon savings at the pump, it is not worth it and now i hate our shell station...with the onboard computer screen, it is easy to see which stations have good gas and which dont..
chris

 

[philliph]

I just logged on to ask the exact same question, and I see this thread is already discussing my issue. I have a new 08 HiHy with just 1000 miles on it and noticed this almost from the start. When stopping, the regen braking often kicks in for a second, disengages, and for that split second afterwards there is a sensation that your brakes are partially released, and then the normal brakes kick in and take over the stopping job. I agree that this happens when the battery meter is one bar down. But, this is most of the time. So my query is this: I wonder if the computer is keeping my battery "too full" from routine driving operations? If the battery was kept at a slightly less charge, then I would not be wasting that braking energy on regular brakes. Is there a dealer setting that can tell the computer to keep the charge slightly less?- or am I on the wrong track here?

 

[chuck960]

Philliph, this is exactly what my vehicle is doing. The battery is being kept at too high of a charge so that there is no room to recapture the braking energy. For the first 10000 miles I didn't see this at all. Even in the winter the motor/generators charged the battery down to a couple of miles per hour.
Have you had any luck with service?

 

[JSTCD]

Me Too

My car does exactly this.

I feel the occasional braking "hiccup" when the brakes seem to suddenly fail and return. I always figured it was a peculiarity of the computer ssytem.

I aslo feel the battery is being kept too full, and am constantly trying to get the "energy out".

I get HORRIBLE mileage at times, because I am constanlty reving the engine, and charging the bat, even though it is already almost full.

I have a code reader, so i can tell you, the car is throwing no codes.

I just got my HIHI and there is no doubt that many of these problems are getting better now that the weather is warming up. And i have found that most of these problems go away once the car is fully at temp, and that can take up to 15-20 min in very cold weather.
Unfortunately for me all my driving is less than the warm up time for my HIHI.

I am working feverishly on a circuit that will fool the hihi computer into thinking it is already warm. Early test have been great. Cut my fuel consumption hugely. Aprox 16mpg to 26mpg in cold weather.

The only other unkown it the Idle Speed Control. If the batery is disconected or drops too low, the computer forgets the ISC. The manual states it must be reinitialized or the engine will run at low fuel economy and too often. Which sounds like everyones problem. You need a factory Toyota scan tool to tell if this has in fact been done, and i think maybe even to do it. I am not sure of the ISC learn status on my hihi. Anyone know how to tell?

 

[Jay Levenson]

'06 HH Brake Regeneration Fails

I too have this problem with the braking regeneration cutting out. Been in the shop 3 times for this. Factory rep gave scenarios that were "normal" - 1) Full charge, 2) Anti-lock engages on bumpy road, etc. This does not explain sudden decline in mpg (down to 20-22) when the problem appears. Has been happening in hot weather, not cold (so far). First appeared during near 100 deg days. Now happens even at 70.