I took a great big Smoky Mountain Trip today. There were several times when I had downhill grades 2, 3, or 5 miles long. I used B - Mode, after maxing out the battery bars - But today, the first time I dropped into B (at maybe 45 - 50 mph) it sounded like the 'ol baseball cards on the bicycle spokes to produce a motor sound trick. I've never had this kind of clattering before, even when using it at 70 or 75 on long interstate grades. Any idea? Is this something to be checked out at the Toyota dealer? I would appreciate any help!:yo:
if the battery is full, the engine revs up like a jake brake..it's spinning without fuel. when the battery isn't full, the electric motors spin up to charge along with the engine. so it revs but quietly. all it's doing is pulling air since the drag of having to pull air without fuel slows the vehicle. keeps it maintainable anyways.
So let me get this straight - When it makes noise (and going a sufficient speed to create said noise) the battery is in fact full, and using B-mode was appropriate (to save conventional brakes). If at the same speed, it does NOT make noise, then the battery probably wasn't actually full, and I shouldn't have used B-Mode quite yet - Right?
Correct, mostly. Remember when you use B-Mode you are requesting engine braking whether you need it or not. One way you can tell you are using engine braking is if the engine gets quieter when you step on the gas. Stepping on the gas calls for more speed, so the control system reduces the drag from the ICE by spinning it slower. Tom
Balloons on your spokes make your bike sound like a Harley - but they don't last long! Thanks for your help!
The official Harley sound, as written in a legal filing by Harley, is "potato, potato, potato..." Tom
Yes, normal. You should use "B" on a long downgrade, when needed to save the brakes, without regard to the state of charge of the battery. The car will manage the battery by itself.
Update on this thread - On my weekend mountain trips I've discovered that if I use B-mode as soon as the MFD shows full battery that it must not be quite full, because the "jake brake" doesn't roar until I regenerate a bit more. Is this a similar experience that you other mountain travelers are having?
Update on this thread - On my weekend mountain trips I've discovered that if I use B-mode as soon as the MFD shows full battery that it must not be quite full, because the "jake brake" doesn't roar until I regenerate a bit more. Is this a similar experience that you other mountain travelers are having?
Yes. (For the occasions I have descended the Blue Ridge.) A little technical background: A "full" battery as shown by eight green bars is not exactly full. The car babies the battery to avoid over-charging and over-discharging. The MFD battery display actually reflects a range from 40% to 80%+ charge: So the eighth green bar may light with as little as 75% SOC, though it has room for a little more charge. Then as the 80% threshold is reached (and occasionally exceeded -- I have seen it as high as 82% with CAN-View), the car stops accepting more regeneration and instead becomes more aggressive in trying to reduce SOC. This includes using one of the motor/generators to spin the ICE at a higher RPM during coasting -- undoubtedly what you hear as "roaring." It also includes, incidentally, an increased tendency to use only electricity when propulsion is needed. It's a paradox of sorts: ICE RPM goes up when you let off the gas pedal, and the ICE shuts down when you step on it. I'm surprised no one has linked this article yet. It's a good discussion of how B mode works. Another item worthy of mention. If SOC tops 80%, the car itself will intervene regardless of whether you're in B mode. See this for the observations of several of us who have seen B-like behavior while in D.
This is my experience as well. You have a little more room for charge even after all the bars are green. Tom
