I was going down a pretty long hill, about 1 mile and I had the trans in brake mode and the battery got real full, real fast. Once it hit full, about 10 seconds later I started to smell a burning electrical smell. I put it back into drive, but I still had to brake down the hill. This continued on for about 30 seconds. I thought maybe the batteries were going to explode, is this normal?
Gasitman, There are NUMEROUS posts about what your describe. There is a lot of suggestion to use "B" when going down a steep grade. Was this a Steep grade or gentle hill? It was mentioned in many posts that putting the Prius in "B" acts as a braking mechanism and also disperses the energy from the downhill braking.. I am not sure if you were using your brakes or not, but it could have been them?? I can't think that your traction battery was jeopardized in any way. May I suggest searching some of the posts for using "B" mode and the comments and answers I believe are there in more detail. Here is one I found on a post for you from EFusco: 1)Don't use B-mode--Unless you are routinely going down very long (3-4 miles) steep (6% grade or greater) and topping off the battery while doing so to the point that you no longer recapture energy with regenerative braking. I dare say there are very few of us who do that. 2)You did no harm and the first reply is accurate and the quoted reply is inaccurate. When you have your foot on the go Pedal B-mode is identical to D-mode. Only when you lift your foot off is there any difference and that is that you engage engine braking as well as greater regenerative braking/coasting.
I am a bit confused, in one sentence it says the energy is dispersed, and in another it says do not use the B for braking unless your going down a 3-4 mile hill. It was a significant grade. I do not think it was the brakes, I know what burning brakes smell like, this was definitely a electrical smell. But thanks for the posts, I will look at some of the other threads now.
In a nutshell, use B mode only when you want to discard energy, such as down a mountain. D mode down a hill will eventually kick in engine braking if the hill is long and steep enough. Manually selecting B mode does it immediately and a little more aggressively. The hot smell you experienced comes from heavy regeneration, which works the inverter pretty hard. It's normal for it to smell hot in such a situation, especially if your Prius is new. Think of how a new exhaust system smells when you first get it hot. It's sort of like that, only with the electrical system. Tom
IMO, B mode shouldn't be needed unless the grade is posted and there are signs warning truck drivers to downshift. Even under these conditions in western PA I didn't use B mode in the 2006 & did not experience any smells.
Yes, what Tom said. My rule of thumb for B mode is use it if the battery will be full on the display by the time I reach the bottom of the hill. It will reduce service brake use and the load on the battery. If you don't use B mode on a long steep hill the system will burn off the excess energy put into the battery by spinning the engine anyway plus you would be using more of your service brakes, causing wear and heat build up in the brakes. Save your brakes for when you really need them but don't use B mode unless the battery will be full at the bottom of the hill.
Could you use Google Earth to give the longitude and latitude of the top and bottom of the hill? What speed? Can you reproduce this? ... Is it a regular route? The reason I ask is ordinary driving should not harm this car and while the 3/36000 mile warranty is in effect is the best time to test the limits. <wink> Now after the 3/36000, 60,000 and 100,000 mile warranties are over, YIPPIE! Lab time! Thanks, Bob Wilson
Google earth search term: "I-90 Snowqualmie pass" led me to: "Snowqualmie Dr, Layton, UT 84040" Not much of hill there but it only matches the accuracy of the description. Bob Wilson
Snoqualmie Pass WA snoqualmie pass - Google Maps [ame]http://en.wikipedia.org/wiki/Snoqualmie_Pass[/ame]
Are you serious? Snoqualmie Pass? I hardly use B-mode on Snoqualmie, and certainly can't fill up the battery in normal weather. It just isn't steep enough for long enough. If the cold weather caused you to cross the summit with 7 bars, then maybe it might fill up, barely. The battery easily fills up elsewhere, forcing serious compression braking -- Stevens Pass, Washington Pass, Loup Loup Summit, Waterville - Orondo hill, Lewiston Grade, Whitebird Hill, Mt. Idaho grade, Going to the Sun Highway, Granite Pass, Powder River Pass, Iceberg Pass / Trail Ridge Road, Berthoud Pass, Pikes Peak Road, Monarch Pass, Monitor Pass, and many others. But not Snoqualmie Pass. The first few times you get it on a serious hill, powering up or regenerating down, the heat will push some odors off the fresh materials. And when the battery fills going downhill, the engine goes into compression mode and produces a fairly loud engine noise. I liken it to a giant vacuum cleaner under the hood. Other posters have had other descriptions of this 'screaming' engine braking noise.
Yes he is serious. You asked for help. Knowing Bob, he is liable to spend one if not several hours of his time trying to help you.
FWIW, I can fill my 06's battery to 80% causing the ICE to start just going down NE 40th St. on Redmond, WA towards Lake Sammamish. See route from: 15850 Northeast 40th Street, Redmond, WA 98052-5283 (Timberlawn Apartments) to: ne 40th st and west lake sammamish pkwy ne, redmond, wa - Google Maps. Via ScanGauge, I can watch soc hit 80% and even though I'm well below 42 mph (HVAC is off), the ICE fires up and there's no regen at that point (BTA is positive). But, that won't go on for too long because by that point, I'm near the end of NE 40th St.
As far as I can tell, using B mode downhill, or using the brake pedal, both slow by regeneration, unless severe braking. I use B a lot because it acts as a downhill cruise control, keeping the speed to that when it was engaged. I have not yet tried a long, steep hill on my gen 3, but have driven 5 years in a gen 1. Many times I have experienced the battery indicator going to the very top going downhill. Never had a smell, but once the little turtle warning lamp came on on a very long, steep and twisty hill coming down from the Sierra Nevada. This could not have been for low battery (Toyota states), as the indicator was at the top. I assumed the battery was overheating and pulled over for a while with the system on. Is there any gen 3 indicator for the battery overheating?
Having hit 8 bars on a lesser hill two days in a row (regen braking only, not B-mode), I now believe that you can fill the traction battery coming down Snoqualmie, at least in winter. Mine is filling faster in this weather than it did in summer.
Since we are specifying passes, the one I had a problem is the Sonora Pass, California 108, which descends 2900' in 10 miles.
Mine will fill up to green bars on the flat in cold weather. It's a side effect of making heat. As long as the ICE has to run, it tries to put some charge into the battery. Likewise, a cold battery will hold less charge. Tom
