Prospective RX Purchase

[Illogan]

15 hours ago, Spacewagon52 said:

What I can't get over is how seamlessly this all happens. Unless you are listening carefully, you would not have a clue which part is working. The energy monitor can be addictive and is a safety hazard! Don't look while driving! Get the wife to do constant read outs … he he! It is driving her crazy! I am still ploughing through the manual and do expect to find new things! The reversing camera and reversing sensors are wonderful. Not worked out how to engage the front sensors yet.

Get up to speed and then take your foot off the throttle - car begins to charge battery. Press VERY gently and Electric only will be engaged

 

Brake gently and the electric motors, via dynamos (?) put energy back into the hybrid battery to be used again!

 

 

And welcome to 'Our World'

It is just 12 months since we bought our S3RX450 , and what a wonderful move it's been.

I still enjoy the simple act of driving him, (all my cars have been male), the technology is just too good not to enjoy, and as I'm never in an hurry*, driving to improve the mpg has almost become an hobby.

The blasted Coronavirus has severely curbed our 12 months mileage (3,500!), and the next 12 months looks though it will be none to substantial either, but I take great pleasure in every mile that I do drive: (and avoid rush hour, avoid London and the Home Counties and try to avoid the eedjits).

*Hurrying: the idea scenario is that the very next time I'm in a vehicle that's hurrying - it'll be on its way to an hospital, I cannot think of anything else I want to rush for)

[ColinBarber]

5 hours ago, Herbie said:

I agree with everything you said above Colin except for this last little bit.

That may be the case on a long downhill stretch when the traction battery is fully charged and can accept no more, although I'm not even sure about that - if the traction battery is full and the excess supply has to be dumped, wouldn't the charge meter needle rise to the top of its scale, indicating no charge taking place?

However, that's a different thing so I'll leave that there.

Even just normal driving around town, approaching traffic lights or junctions will see the power meter needle drop right down indicating maximum charging but the mechanical brakes don't come on at that point. As the car slows down the needle will rise because MG1 is reducing speed, and consequently electrical output, all the time but it's only when the road speed gets down to somewhere between 7 and 3mph (can't remember exactly) that the change from regen to mechanical braking takes effect.

I state further down that regen braking will stop if the Battery gets full - and yes the needle will return to 0 indicating that fact.

 

If you apply braking beyond what the hybrid system can generate then the mechanical brakes work in conjunction with the hybrid braking. The electrical force generated is related to how fast the generator is spinning, due to the electro-magnetic forces at work, so yes if you keep the same pressure applied you will start to see the needle move back towards 0, at which point you can apply a bit more pressure and still be within regen braking.

Your last paragraph is incorrect. The mechanical brakes will operate once you max out the regen capabilities of the hybrid system at any speed. If you were to slam on the brakes at 70 mph the relatively small electric motor/generator cannot slow a 2 ton vehicle that quickly, and it is further limited by the batteries because they cannot take the full charge current that the generator could produce. In that situation it is probably 99% mechanically braking that is doing the work. But at even quite low braking requirements you will see the needle max out and the mechanical brakes take up the extra requirement. This is all controlled by the skid control ECU on the 400h:

 

At around 5 mph, the regen braking system is completely disengaged, the mechanical brakes then do all the work. You can sometimes feels that as the timing may not be 100% accurate during the transition and you get either a slight feeling of acceleration (actually less deceleration) or greater deceleration for a split second. It is rare to feel this on the modern generation hybrids but the first and second gen Toyota systems you sometimes can (Prius I and Prius II RX400h, GS450h series II).

[Spacewagon52]

3 hours ago, ColinBarber said:

I state further down that regen braking will stop if the battery gets full - and yes the needle will return to 0 indicating that fact.

 

If you apply braking beyond what the hybrid system can generate then the mechanical brakes work in conjunction with the hybrid braking. The electrical force generated is related to how fast the generator is spinning, due to the electro-magnetic forces at work, so yes if you keep the same pressure applied you will start to see the needle move back towards 0, at which point you can apply a bit more pressure and still be within regen braking.

Your last paragraph is incorrect. The mechanical brakes will operate once you max out the regen capabilities of the hybrid system at any speed. If you were to slam on the brakes at 70 mph the relatively small electric motor/generator cannot slow a 2 ton vehicle that quickly, and it is further limited by the batteries because they cannot take the full charge current that the generator could produce. In that situation it is probably 99% mechanically braking that is doing the work. But at even quite low braking requirements you will see the needle max out and the mechanical brakes take up the extra requirement. This is all controlled by the skid control ECU on the 400h:

 

At around 5 mph, the regen braking system is completely disengaged, the mechanical brakes then do all the work. You can sometimes feels that as the timing may not be 100% accurate during the transition and you get either a slight feeling of acceleration (actually less deceleration) or greater deceleration for a split second. It is rare to feel this on the modern generation hybrids but the first and second gen Toyota systems you sometimes can (Prius I and Prius II RX400h, GS450h series II).

I am blown away with this technology! AND it is 15 year old technology at that! Your knowledge is amazing! Thank you both for sharing!

[Herbie]

20 hours ago, ColinBarber said:

Your last paragraph is incorrect. The mechanical brakes will operate once you max out the regen capabilities of the hybrid system at any speed.

Guilty as charged, by omission, although I have mentioned in a few previous postings that if you have to slam on the anchors in an emergency then the system goes directly to mechanical braking; I just forgot to include it here.

20 hours ago, ColinBarber said:

But at even quite low braking requirements you will see the needle max out and the mechanical brakes take up the extra requirement.

Are you saying that the mechanical brakes come on whenever the power meter indicates maximum charge?

I don't know how many Amps are being squirted into the traction Battery when the power meter indicates maximum charge, but I assumed that some current-limiting circuitry comes into play to limit the rate of charge so that the Battery isn't damaged. In other words, the Battery still has the capacity to accept more charge, so regen braking still continues with the electrical output of MG1 being limited, until the car slows down enough for the mechanical brakes to take over.

[Spacewagon52]

Sorry to but in, but you are talking about the 400H? Yes?

[Herbie]

37 minutes ago, Spacewagon52 said:

Sorry to but in, but you are talking about the 400H? Yes?

Yes and no I suppose

I know it started off as being the 400h but I would think the points being discussed could be applied across the range of hybrids, but maybe not?

[Spacewagon52]

The braking feels very different from my RX 300

[Herbie]

22 minutes ago, Spacewagon52 said:

The braking feels very different from my RX 300

Yeah it will do because as you know, the RX300 only has mechanical brakes.

It doesn't take long to get used to the regen brakes though. Just anticipate the road ahead and brake gently whenever you can, so as to get the most from the system.

[BartLexusFan]

Not sure what to expect from the RX450h then, as I couldn’t tell the difference in breaking between my 3GS450h, LS430 and 2GS300. No, wait. I’m lying. Brakes on LS430 were so good, couple of times I’ve bitten the steering wheel. Really enjoying this thread David, haven’t driven a hybrid in 4 years, cannot wait. Saturday can’t come soon enough!

[Spacewagon52]

2 hours ago, BartLexusFan said:

Not sure what to expect from the RX450h then, as I couldn’t tell the difference in breaking between my 3GS450h, LS430 and 2GS300. No, wait. I’m lying. Brakes on LS430 were so good, couple of times I’ve bitten the steering wheel. Really enjoying this thread David, haven’t driven a hybrid in 4 years, cannot wait. Saturday can’t come soon enough!

I would like to say I am excited for you   ... BUT NO! You stole it from me! It should have been mine!

 

Really hope you enjoy it Bart!

[ColinBarber]

6 hours ago, Herbie said:

Are you saying that the mechanical brakes come on whenever the power meter indicates maximum charge?

Yes. Although not just me, Toyota are. Or to be more precise, the mechanical brakes are used whenever the braking force requested by the driver exceeds the capacity of the regenerative system - which is anything other than light braking as you can see from the power meter.

[Herbie]

6 minutes ago, ColinBarber said:

Yes. Although not just me, Toyota are.

Haha, fair enough Colin, every day's a school day

[ColinBarber]

44 minutes ago, Herbie said:

Haha, fair enough Colin, every day's a school day

Found some more information on the subject from the 400h documentation:

 

[Spacewagon52]

Had I known all this I would have run a mile! The possibilities for problems here are endless! Calm yourself David - YOU OWN A LEXUS!

[Herbie]

Aha! Now I understand it better, having seen that last diagram, so thanks @ColinBarber

[A-Rod]

Hi All,

Sorry to be hijacking this thread, but with 2008-09 RX350 being almost unavailable (one on eBay without nav) in the UK, I'm now going back on the RX400h researching route.

I have seen a lot of complaints on US forums pertaining to the hybrid batteries fault codes and/or failures, setting owners back thousands of USD; one Brit commented on those threads saying he had to fork out in excess of £4000 to get one fitted.

Having looked browsed on this forum, I note that not a lot of people are having issues with the hybrid systems - is it too soon and perhaps in another 3 years the below 2008 models will begin suffering low charge / issues?

Has anyone had to replace their hybrid batteries?

Also, I note that pretty much every single 2008-2009 car I have seen hasn't got both front and rear sensors but only comes with rear cameras. I'm used to driving big cars as owned a 2010 Phaeton, which came with front sensors that are a must for the car of that size. How do you guys cope without any front sensors? I have seen two cars on AT, one has had front and rear retrofitted, and the other seems to have it from factory being an 09 plate executive limited edition model (please correct me if I'm wrong).

I was expecting some form of sensors / camera at the front for the vehicle of this size.

[royoftherovers]

You have asked the big question Den. I think you will be amazed.

[Herbie]

1 hour ago, A-Rod said:

Also, I note that pretty much every single 2008-2009 car I have seen hasn't got both front and rear sensors but only comes with rear cameras.

Front sensors were never a factory fit but rather a dealer option, so some will have them, some won't, depends what the original owner specified. You could always fit your own.

And no offence meant, I promise, but knowing the length of your vehicle is a skill that everyone should already have. How do you think all the truckers, van drivers and others manage? Or how did anyone manage before the advent of the parking sensor and/or camera?

Watch any American TV programme from the 60s, 70s and 80s and look at the size of their cars - no parking sensors around then.

[BartLexusFan]

I think what A-Rod wanted to say is that Lexus is a luxurious brand and he's surprised that RX doesn't have parking sensors. To be honest it all depends on spec and time, and sadly they were only a dealer option as Herbie mentioned. When I was looking for RX400/450h there were at least 5x 350, but I prefer hybrid drive anyway regardless of MPG/Performance. Just to put it in perspective some S Class Mercedes Benz cars from 2005 were so basic they didn't include not only front and rear parking sensors but even a reversing camera.

And MB S Class is supposed to be the pinnacle of luxury. 

[rich1068]

I also find that since having a camera on my RX parking sensors are a poor substitute.

[A-Rod]

What amazed me is the fact that top level trim on the RX400h models, SE-L / Executive Limited Edition, didn't come with any sensors as standard but only a camera at the back. I just find this a bit odd, not a deal breaker but just odd that you'd need to ask a dealer to fit them for you at the time of purchase when new.

If you'd pick the flagship trim on an S-Class, it would in fact come with all the bells and whistles, including front and rear sensors. Even Rolls Royce offers base models that do not come with many factory options (sensors isn't one of those) - but I'm talking about top level trims here.

Sorry I should've mentioned I was after the SE-L trim that comes with ML audio system. I'm still looking for one and hoping to buy a good example by the end of next week. Just need to continue my research.

The 08-09 models with 110k/120k tend to sit between £5.7k - £6.5k range. Is that the norm?

[Spacewagon52]

1 hour ago, rich1068 said:

I also find that since having a camera on my RX parking sensors are a poor substitute.

That is interesting as my old Mitsubishi had both and I relied more on the sensors to be honest.

 

My RX 400h has camera plus front and rear sensors - all I am sure will come in  handy

[Spacewagon52]

2 hours ago, A-Rod said:

What amazed me is the fact that top level trim on the RX400h models, SE-L / Executive Limited Edition, didn't come with any sensors as standard but only a camera at the back. I just find this a bit odd, not a deal breaker but just odd that you'd need to ask a dealer to fit them for you at the time of purchase when new.

If you'd pick the flagship trim on an S-Class, it would in fact come with all the bells and whistles, including front and rear sensors. Even Rolls Royce offers base models that do not come with many factory options (sensors isn't one of those) - but I'm talking about top level trims here.

Sorry I should've mentioned I was after the SE-L trim that comes with ML audio system. I'm still looking for one and hoping to buy a good example by the end of next week. Just need to continue my research.

The 08-09 models with 110k/120k tend to sit between £5.7k - £6.5k range. Is that the norm?

I paid more for my 08 because it was in good condition, service history and low mileage. Does not guarantee something will need doing in the not too distant future, as the car is 12 years old.

The big difference in price is between the 4ooh and the 450h - similar age and mileage you can pay 30% more for the 450h. You takes your money...................etc

[Spacewagon52]

Had the caliper pin sorted today ........ however the garage said that when I replace the brake pads I will need a NEW caliper (as the pin does not retract enough? I think that is what he said)

 

Lexus calipers £250 each I believe?  Will be saving up! LOL!

 

I do understand the reasons for the caliper pins to seize - lack of use due to regenerative braking - but apart from servicing the rear brake caliper each year, how can I get the rear brakes to come on now and then?

Reversing quickly (safely) and slamming on the brakes? Harder severe braking?

Any suggestions ? Just to keep them working?

[Spacewagon52]

The technology still blows me away Colin and Herbie!