Loving our RX450h but...

[welland]

Can I just introduce another element that I didn't spot in thix thread yet. (Sorry if it's been covered and i didn't spot it)

While stationary with the car in D, does it matter whether the car is held with the foot brake or the parking brake?

Ok, my car is an rx400h, so perhaps different to the original subject of this thread, but I recently observed something interesting. While stationary on the foot brake, the energy monitor showed no energy flowing.   However, if I engaged the park brake and took my foot off the brake, the energy monitor shows energy flowing from Battery to wheels.  This seems to imply that holding stationary with the park brake while in D is a bad thing.  

What do y'all think?

PS: no jokes about park brake being operated by foot!😉

[SLACKBLADDER]

Oh Dear covered look for your problem on forum 

[Chris Skelton]

Now....look outside, the sun is shining........

[SLACKBLADDER]

And I'll put the top down and cruise  hehe 

[ISJason]

Can I just introduce another element that I didn't spot in thix thread yet. (Sorry if it's been covered and i didn't spot it)
While stationary with the car in D, does it matter whether the car is held with the foot brake or the parking brake?
Ok, my car is an rx400h, so perhaps different to the original subject of this thread, but I recently observed something interesting. While stationary on the foot brake, the energy monitor showed no energy flowing.   However, if I engaged the park brake and took my foot off the brake, the energy monitor shows energy flowing from battery to wheels.  This seems to imply that holding stationary with the park brake while in D is a bad thing.  
What do y'all think?
PS: no jokes about park brake being operated by foot![emoji6]

I don’t think you are generally supposed to hold an automatic transmission on the parking brake while sitting in traffic, unless your in a massive tailback, then you might as well put it into park anyway.




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[ColinBarber]

On 15/04/2018 at 10:13 PM, welland said:

Can I just introduce another element that I didn't spot in thix thread yet. (Sorry if it's been covered and i didn't spot it)

While stationary with the car in D, does it matter whether the car is held with the foot brake or the parking brake?

Ok, my car is an rx400h, so perhaps different to the original subject of this thread, but I recently observed something interesting. While stationary on the foot brake, the energy monitor showed no energy flowing.   However, if I engaged the park brake and took my foot off the brake, the energy monitor shows energy flowing from battery to wheels.  This seems to imply that holding stationary with the park brake while in D is a bad thing.  

What do y'all think?

PS: no jokes about park brake being operated by foot!😉

There is possibly nothing worse that holding a hybrid in D on the parking brake. The system uses the main brake pedal as a signal to provide hybrid power or not. Take your foot off the brake and it uses the electric motor to provide forward creep, simulating a standard automatic transmission. Holding it in that mode on a handbrake is depleting the batteries and heating up the electric motor.

Either hold the vehicle in D using the main brake, or place it in Park.

[Ala Larj]

21 minutes ago, ColinBarber said:

There is possibly nothing worse that holding a hybrid in D on the parking brake. The system uses the main brake pedal as a signal to provide hybrid power or not. Take your foot off the brake and it uses the electric motor to provide forward creep, simulating a standard automatic transmission. Holding it in that mode on a handbrake is depleting the batteries and heating up the electric motor.

Either hold the vehicle in D using the main brake, or place it in Park.

I have a 'hold' function on mine which means I can take my foot off the foot brake whilst leaving it in D. I guess that must be an automatic foot brake rather than applying the hand brake. Will have to look at the energy meter next time I use it.

[ColinBarber]

43 minutes ago, Ala Larj said:

I have a 'hold' function on mine which means I can take my foot off the foot brake whilst leaving it in D. I guess that must be an automatic foot brake rather than applying the hand brake. Will have to look at the energy meter next time I use it.

It does hold the brake pressure rather than applying the parking brake.

But if it did use the parking brake, because the vehicle's electronics has performed that action it could feed that input into the hybrid system so it doesn't try and pull away.

[Ala Larj]

After about four minutes it automatically applies the handbrake. Surely that then creates the problem that you say shouldn't be done. Very confusing. I'm sure Lexus must have thought of that!

[ColinBarber]

I believe it applies the main brakes, not the handbrake, and as I said above, if they used the handbrake it would have been integrated so it doesn't cause a problem.

[Glover]

Bit late to this but I agree with those who say leave it in D or shift to P.  In the owners manual for Series 3 RX450h there's a notice stating:  

"Hybrid Battery (traction battery) charge precaution
If the shift lever is in N, the hybrid Battery (traction battery) will not be charged even when the engine is running. Therefore, if the vehicle is left with the shift lever in N for
a long period of time, the hybrid Battery (traction battery) will discharge, and this may result in the vehicle not being able to start"

I've always left the car in D at lights or when stopped unless it's going to be a long wait e.g. traffic jam and the traffic is unlikely to move fairly soon in which case I shift to P and apply the parking brake.  I assume Lexus would advise shifting to P or N if sitting in D had an adverse impact on the vehicle.

If I'm parked up listening to the radio I put it in P and follow the tip from a poster in another topic, which is to put the car in EV mode.  The radio will run off the hybrid Battery for about 20 minutes at which point the engine starts, puts some power into the hybrid Battery and then the engine switches off until the Battery gets low again.  It will keep doing that for as long as you want.  There's obviously a slight impact on fuel consumption especially if you are parked up in winter and have heating or seats (or both!) on.

[Guest]

Hi sorcerer,

wrt neutral when stopped, yes you should. For 3reasons,

1, that’s what the Highway Code says. (Reason for it is that If your foot slips you will move fwd, possibly hitting the vehicle in front).

2. It means you brake lights aren’t on, which can get very annoying for those behind you in low light or at night. ( It can dazzle other drivers, which can be punishable by up to a £1000 fine! A friendly police officer explained that to me once after I’d done exactly as you do when driving through a series of lights one night!

3. Possibly more important for the car -  If you look at the power flow monitor on the dash, you’ll see that the Battery continues to feed the electric motor to drive the car fwd, which is stalled as you are stopped, means your Battery is only going to discharge and may cause the motor and converter to overheat as a stalled (stopped) electric motor draws a high current but in this case, can’t turn. Eventually, the engine will have to start to recharge the Battery.

Its similar to a ‘slush box’ auto, in ‘drive’, the engine continues to drive the torque converter but the gearbox can’t turn as the car is stopped, this rapidly heats the oil in the converter. Not too big an issue as long as everything in the oil cooling system is 100%. However, any issue there could cause the gearbox to overheat. I think new gearboxes or front electric motors are probably more expensive than brake pads and brake fluid.

my father taught me most of this years ago when he was both the drivers union rep for shell tanker drivers where he worked as a driver and he had an advanced licence. The rest came from my brother who was a police officer until he retired.

Also, I’m an engineer and have spent my life working out why things break and how those breakdowns could be avoided, sometimes it’s down to how people use the equipment.

If I’m  going to be stopped for a few seconds, I leave it in drive, if (for example) the lights change to red as I approach, I put the car in neutral with the handbrake on once stopped.

But enjoy the motor!

Dave F

[ColinBarber]

10 hours ago, 56Doc said:

 

3. Possibly more important for the car -  If you look at the power flow monitor on the dash, you’ll see that the battery continues to feed the electric motor to drive the car fwd, which is stalled as you are stopped, means your battery is only going to discharge and may cause the motor and converter to overheat as a stalled (stopped) electric motor draws a high current but in this case, can’t turn. Eventually, the engine will have to start to recharge the battery.

 

Incorrect and against what the user manual advises!

If you are stationary and your foot is on the brake, all power is removed from the motor - it is not stalled.

[Guest]

Yeah, spotted that next time out, footbrake switches off drive, parking brake doesn’t!

[noby76]

On 5/2/2018 at 10:37 PM, Glover said:

"Hybrid battery (traction battery) charge precaution
If the shift lever is in N, the hybrid battery (traction battery) will not be charged even when the engine is running. Therefore, if the vehicle is left with the shift lever in N for
a long period of time, the hybrid battery (traction battery) will discharge, and this may result in the vehicle not being able to start"

 

Does this mean the batteries discharge during a traffic stop and Neutral is selected? if the Battery already has enough charge before the traffic stop  I am guessing selecting N shouldn't impact the restarting and moving of the car so long as there is enough harvested charge prior to stopping? 

[sorcerer]

1 hour ago, noby76 said:

On 5/2/2018 at 10:37 PM, Glover said:

 

Does this mean the batteries discharge during a traffic stop and Neutral is selected?

Yes, it does.

1 hour ago, noby76 said:

if the battery already has enough charge before the traffic stop  I am guessing selecting N shouldn't impact the restarting and moving of the car so long as there is enough harvested charge prior to stopping? 

It depends on how long you're in neutral for and how much electrical load is on the system. In winter you may have headlamps on, heated seats, cabin heater etc., in summer the aircon and other stuff.

Bottom line - just get used to keeping it in D with your foot on the brake or for longer periods, select P.

Both D and P will cause the engine to fire up to provide charge to the traction Battery if it gets too low, but in neutral it won't - it will just continue to discharge and may get so low that it can't restart the engine.

[Ala Larj]

1 hour ago, sorcerer said:

Both D and P will cause the engine to fire up to provide charge to the traction battery if it gets too low, but in neutral it won't - it will just continue to discharge and may get so low that it can't restart the engine.

Exactly. It states this quite clearly in the handbook.