B Mode

[Duffryn]

Sorry if this subject has been done to death previously, but after trawling through earlier threads I still can't find a definitive answer to my query, which is:-

Is there a speed above which one shouldn't travel while in B (brake) mode?

Thinking here of long downhill stretches such as Telegraph Hill near Exeter, or (my regular) Crickley Hill near Gloucester. Given a free run the car would probably exceed 100mph in N or D mode down these hills, but in using B mode the engine seems to rev too much, and not having a rev counter doesn't help. I always tend to use plenty of footbrake to keep road and engine speed down, thereby keeping the hybrid Battery full for some while of course. And probably annoying the guy behind me too!

Just concerned if any damage could result by being in too high a speed for some distance while in B.

[unclepoo]

If you`ve got cruise control, try using that....regeneration and braking will be done for you.

[kithmo]

There will be a limit to which the engine will physically rev when acting as an air pump with the valves closed and the engine is being lubricated, so I can't see it doing any damage. The top speed when driving the engine is something like 109 mph IIRC and the revs at that speed will be well below the safe maximum, so at 100mph in B mode you're doing less revs and there's no combustion heat to burn oil, so it should be actually better for the engine than driving at top speed.

[Grumpy Cabbie]

According to Priuschat the car will look after itself in B mode. I've had it rev itself away alarmingly too, but no worse than driving the car UP a hill when it uses petrol. Be aware the engine revving during B mode doesn't use any petrol.

You're more likely to do damage to the car by not using B mode if you regularly travel down that hill causing the HV Battery to max out (as max as it will allow) too often.

If you leave the car in D and use the foot brake to slow the car, you will have found that the car will switch off regen braking when the HV Battery is maxed out. This can be alarming as you find out how much braking regen offers, and how poor your friction brakes are when used exclusively at speed.

[timberwolf]

B Mode is there to avoid the deadly consequences of friction brake fade.

[Duffryn]

Cheers for that guys, concerns stood down now.