battery and driving on a long slope downhill

This summer I drove quite a lot downhill. There were moments that the battery was 100% full (all bars visible). I checked whether there would be 'little cars' displayed in the display indicating regenerated energy. When the battery was 100% full there was indication anymore about the amount of regenerated energy, and that sounds logic to me. I have experienced nothing negative in these situations. Thibaud

A few years ago, I had all thirty minutes of those five-minute 100 MPG bars, and the resultant green bars on the battery. Driving from Reno to Sacramento is almost all downhill, so even at highway speeds, you're charging the battery a lot.

When the battery is partially charged the motor/generator combines with the engine brake effect to keep the car going slowly downhill. Once the battery is fully charged the control systems in the car prevent any further current from reaching the battery and the car depends on engine braking alone. The only thing you will notice is that the engine note on overrun sounds a bit higher (because it's working alone) and you may have to use your brakes a little more.

Some Prius owners suggest that it is better to use your regular brakes rather than the B position anyway - more charging current gets to the battery under normal braking than engine braking - but this only holds true until the battery is fully charged, after which the above applies and you will start to wear out your brakes. That would be the time to engage B.

However, it's best to do whatever you feel most comfortable and safe doing. Whatever you decide you need have no fears about damaging the car - it is fully capable of looking after itself.

Enjoy the ride!

Chas

What I've read indicates that the "B" refers only to _engine_ braking, that is, spinning the ICE at a relatively high rate of speed (just like putting a conventional car into Low while giving it no gas). This is in addition to any braking force being applied via the foot brake.

The Prius will not overcharge the traction battery; if the battery is fully charged in normal circumstances, it will use engine braking in lieu of regeneration of power via the motor generator when the foot is lifted; when braking is required on a full battery, conventional brakes will be used.

It is possible to finally reach a point where neither engine braking nor conventional braking is sufficient, just as it is possible with a conventional car; in that case, you may crash, regardless what you are driving.

If you are worried about overcharging the battery, you might want to ensure that the radio and lights are on, and that air conditioning is also running.

No.

The Prius is a highly sophisticated system, much more sophisticated than you're giving it credit for.

Plus, B gear does not charge the battery. Period. End of sentence. Stop right there. Do not ask questions. B gear does not charge the battery. Period.

Nope.

Mine does. At least it adds bars to the display.

cu .\\arc

The rate of the charge done in B mode is *less* than the charge done in D with foot on break. Nevertheless, once charged, D mode rely directly on real break, whereas B still rely on running the ICE in compressor mode. When the downhill is long (mountain size), B mode is interesting: it avoid heating the breaks too early.

Yep.

The first time I used B gear on a long downhill was driving east from Yosemite park on Highway 120 from Tioga Pass to Lee Vining, a drop of about 3000'. My 2008 Prius held a constant speed without needing any foot braking until the battery got fully (as full as the Prius allows) charged. Then the engine sound changed, as though it was speeding up, and I had to use foot braking.

Perhaps your Prius does not charge its battery in B gear, but mine does and apparently so do those of the other Prius owners. If your car actually does not charge in B gear maybe you should have it checked out at your friendly Toyota dealer.

Tom

Well, mine is charging in B-mode when the battery is less then 100% full. This can clearly be seen on the display where the arrows point in the direction of the battery. I can't think of any other explanation when I see that picture. Thibaud

The Prius monitors the battery and never charges above 80% capacity and never discharges below 20% capacity. That is how they get such great battery life. So, in B mode, the battery will charge up to 80% and then quit charging even though the display on the dash shows it it still charging. ---- Posted via Pronews.com - Premium Corporate Usenet News Provider ----