coastin in neutral

[Dr. Martin Gooter Bling]

my car has an unusual quirk. when you drive down a long hill for a protacted period around howth etc. when you drive on flat terrain again the engine idles very high around 3000rpm for a while. it's like the car wants to bleed off all the charge the hybird battery received when going down the hill or something. the way of combating it is to put the car in neutral and roll down the hill and feather the brake. that way the engine and the hybird battery are takin out of the game. i notice as well when i have an annoying cunt onboard and i'm really spanking the car the engine does the same at idle and roars upta 3000rpm for a while. my question is is it safe to slap the car in and out of drive and neutral while the car is moving on an auto car.

[mercenary for hire]

I think that's what the B gear is designed for DMG.It uses the engine to brake going downhill rather than using the leccy motor and overcharging the battery.This way the battery can throw off any excess power and reduce excess wear on your brake pads.

Putting it in neutral might not do any harm but I'd be afraid I'd see a squirrel on Howth hill and forget I'm not in gear and have no accelleration if I needed it.

Next time try B mode and let us know what happens.

[Dr. Martin Gooter Bling]

as far as i can recollect it does the same in B mode.
i'll keep ye posted. thanks.

[mercenary for hire]

The main difference should be that you can still accelerate in B mode in an emergency.If you drive around in B all day your efficiency will drop a fair bit but you probably know that anyways.

[Dr. Martin Gooter Bling]

i've never puttin the car in B mode.
only when tryin to diagnose this high revving at idle malarkey.

[mercenary for hire]

If it's only happening going down big hills it's ok.

My old bolloxed Prius used to over rev when the battery was needing some attention.Usally it was a bogey battery cell and the car couldn't balance the pack so it would keep charging it.That's mmany years away hopefully if you've a newish car.

Just an aside but your battery gets its cooling from the cabin,the vent is in the rear footwell under the rear seat.Make sure you're filter is clean or the battery will be overheating as it can't get cooler air through.Also no harm in running the air con when it's roasting to keep the pack as cool as possible for longevity.

[Octavia1]

as far as i can recollect it does the same in B mode.
i'll keep ye posted. thanks.

Mine does the same ....if I put it in " b"  it reacts the same ...ie it revs for a bit  after down the hill  on the flat in howth ....if I set the cruise control to 50 kmph ...it does the same ...it could be fast idling on the flat for reasons I don't understand but
Ther must be a very good reason for it ... I wouldn't put it in neutral ever down a hill ...on a long one yu cud get brake fade ( not likely but possible ) ... I just trust Toyota have it all worked out an let the fast idle continue ...you won't overcharge the battery ... the computer thingy will cut it off charging ....but I'm still perplexed why it fast idles on the flat ... I tink it mite be to accelerate the coolant flow to cool the engine because even in drive the engine breaking is engaged which despite no fuel going to the engine the compression produces alot of heat .... anyways I think going down hill in idle is not a great idea 

[Octavia1]

It looks like the water pump is electric ...but not sure ...if it is ... then the fast idle is still a mystery 

[Dr. Martin Gooter Bling]

what is "brake fade."

[Octavia1]

what is "brake fade."

It's wen the coefficient of friction ( the grip of your pads on the disc ) reduces  because of overheating to such an extent that you have no brakes ..for the car to slow down it must produce heat ...again this is energy exchange ( thermodynamics) ... in the hybrid the electric motor will convert some of the energy into the battery ...and some energy tru compression in the engine dicipated tru the exhaust ...but the energy must go somewhere...wen yu put the car in neutral ... you  are overriding all of these systems of energy exchange  and forcing all  braking energy   on the pads and discs to slow the car down ...this could result in brake failure in theory ... probly not in howth ...but likely in the alps ide imagine

[Octavia1]

https://en.wikipedia.org/wiki/Brake_fade

[Dr. Martin Gooter Bling]

i can confirm it's even worse in B mode. the revs go up to 4000 and it starts on the descent before you even reach flat terrain again. the only way to drop the revs is to press the accelorator funny enough but why would you press the accelorator and want to go even faster on a very steep windy road?

[Octavia1]

I  use the  cruise control doc an let the cars computer work it out .... it doesn't appear to rev on the flat as much ... or maybe I've learned to ignore it ...its not doing any harm for sure ... in fact it's probably nessessary

[Octavia1]

Bean doin a bit goggling doc ...apparently/allegedly ..
The electric motor is turning over the petrol motor to use up the excess energy an prevent overcharging of the battery ... that would make alot of sense as to why the engine still revs on the flat after the hill

[mercenary for hire]

"why would you press the accelorator and want to go even faster on a very steep windy road?"

We're all experienced on here but there is a school of thought that you are not in control if your vehicle when it is in neutral.If someone walked out in front of you and you swerved and braked you wouldn't be able to get off the middle of the road quickly without stalling and trying to find D mode.Very unlikely because we're all Top gun pilots but ya never know.

I suppose if you were in a heavier vehicle and your brakes failed there's nothing to slow you except the engine.The hand brake might not be much use on a big hill but who knows.

If the electrical system ever fails(extremely  unlikely in a Toyota)your brakes aren't power assisted anymore and you'd quickly notice how shite they become.It used to happen to me very rarely if I didn't put the big orange safety hybrid battery plug in all the way after I had it out of the car.Scary but unlikely unless you were tampering with the vehicle.