CdO

I thought others might find some things I have learned about my NX (450h+) useful. I expect most of these items will be of a technical nature that may not appeal to many; so, I thought I would try to keep it all in one nerdy thread. I'll update this post with links to each new subject.

I have Toyota's diagnostic software "TechStream"... holy cow is there a lot going on inside this thing. So many ECUs; so many sensors; so many "PIDs".

All 2nd Gen NX models:

• All the 'chips' (ECUs)

Hybrid models:

• Pedestrian Warning System Speaker
• Q610 gear ratios (AWD)
• P810 "eCVT" gear ratios
• Launch Mode ??

450h+ specific:

• Lexus App SoC% vs actual state of charge (+MID Bars)
• Lexus App SoC% vs percent of range
• Battery cell details; SoC/V curve
• HV Battery Power Limits
• Reducing Battery Degradation / Capacity Loss
• EV Acceleration

Let me know if there is anything you would like me to look into.

Let the madness begin.

CdO

UPDATE: the latest version of the Lexus App now tells you your miles of range while charging.

This Lexus App state of charge percent drives me crazy.

If I have zero EV range, it says 30% (or 25%). So, I plug it in and it quickly rises to ~38%; but, it's much slower after that... hmm. I check back to see if I have enough charge for my next trip. Now it says 50%. Okay, I'm getting ~48 miles of range; so, I can go 24 miles now? No! I can only go ~10 miles. So, 50% means 22% range? What? And the 8 bars on the "MID"?



The actual state of charge is nothing like what the Lexus App shows and the 8 bars in the MID aren't useful either. Each bar appears to represent a different amount of charge/range and they come on and go off at different levels depending upon whether you are charging or discharging.

How did Lexus come up with this nonsense?

CdO

This info is not terribly useful since the App update; but, I'll put it here anyway as it more clearly illustrates the absurdity of the Lexus App SoC percentage.

CdO

I have struggled with whether or not to eliminate/modify the pedestrian warning system speaker. Yes, there could be legal ramifications for doing so; but, let's not argue about that... anyone modifying their vehicle does so at their own risk. (You can find more info on the RAV4 Prime.)

I find it quite annoying and unnecessary in the forward direction. If I don't have the radio on, I hear it come on when I slow down to ~23 mph. (I value a quiet cabin... I have almost completely disassembled and 'soundproofed' the interior of my other vehicle.)

The speaker is behind the grill under the front crossmember. If you or someone you know has flat hands and skinny wrists, you can reach in and unplug it (otherwise you'll want to remove that front cover under hood (or a belly pan?)). If that's the only thing you do, you'll get an error message and a check engine light (MIL). The light will go away after you plug it back in; but, the error will be stored in the computer until cleared.

The speaker measures close to 4Ω. If you replace the speaker with a resistor from 4Ω to 3.3kΩ you will not get any errors. As for the wattage required? Let's say it's up to 10W (probably closer to 1W). If you use a 4Ω it would need to be rated for 10W. If you use 40Ω, 1W. Anything 160Ω or more only needs to be 0.25W. (Think of all the Watts you'll save!)

Unfortunately, this will also eliminate your alarm confirmation beeper. The rear noise maker (behind/under the bumper) is more difficult to access... and it produces the rear hatch beeps.

I may one day try to add a ~8Ω resister in series to reduce the volume as an alternative... I'll let you know if I do.

toyotaman7

i would not eliminate the pedestrian speaker.

I have a hybrid and that speaker saved my sins life last summer when he was playing jumping in front of the car but heard the speaker to deter him.

It's a live saver. Without it the car is extremely quiet and pedestrians will not know it's moving around them.

CdO

I was actually surprised how much noise the car makes without the speaker. I hoped the ascending/descending spaceship noise was from the speaker; but, it is not. There are some other continuous whining noises that I can't identify/locate... I wonder if they are normal (the car has had 12V issues from birth that cause me to question such things). The noise from all my previous ICE vehicles has failed to prevent many pedestrians from walking in front of them.

This new LSS+3.0 pretty much goes nuts when someone is near the car. It has twice braked to a stop while I was backing out of the garage and my soon to be passenger(s) was waiting off to the side (not in the path of the car). Just minutes ago, it braked to a stop while I was pulling into the garage a few centimeters before I wanted to stop. I would not have hit anything; but, there is an item temporarily close to the car. It seems it would take a high degree of negligence and/or intent to strike a pedestrian (especially in the forward direction).

(Unfortunately, it has no awareness of cars directly beside you (it does if they are a bit back (or forward with FCTA?). It took no action earlier this New Year's Eve night when a car suddenly came into my lane. They 100% would have firmly kissed us had I not been aware and taken action.)

CdO

There's no shortage of chips in this vehicle. The 450h+F has 40 Electronic Control Units (ECUs... 'computers') and there are 2 optional ECUs not available on the 450... not including the Advanced Park option which I would assume would show up in there somewhere. (Perhaps there is just no where left to plug in those extra ECUs?) And I suppose the non-hybrids would have a Transmission ECU.

Some don't do much; but, some measure/sense/calculate loads of info. The Hybrid Control ECU has 415 parameters (PIDs). The HV Battery ECU measures the voltage and internal resistance of each of the 96 cells as well as 20 different pack temperatures, not including all the different temperatures of the various associated components.

Here is a list of the ECUs and the number of PIDs:
ECUs - PIDs
Engine - 265
Hybrid Control - 415 (Hybrid)
Motor Generator - 161 (Hybrid)
HV Battery - 375 (Hybrid)
Plug-in Control - 156 (450h+)
Adaptive Variable Suspension System - 54 (F-Sport)
Brake/EPB - 187
Brake Booster - 36 (Hybrid??)
Tire Pressure Monitor - 101
EMPS [Electronic Motor Power Steering] - 79
Front Recognition Camera - 200
Circumference Monitoring Camera Control Module - 45 (Option)
Steering Angle Sensor - 35
Air Conditioner - 101
SRS Airbag - 90
Main Body - 397
Central Gateway - 8
Back Door - 33 (Option)
Driver Seat - 117 (Option)
Master Switch - 22
Sliding Roof - 20 (Option)
Tilt&Telescopic - 74 (Option)
Combination Meter - 58
Mirror L - 27
Mirror R - 27
Clearance Warning - 168
Headlight Control - 25
Headlight Control (Sub) -12
Smart Access - 160 (Option)
Power Source Control - 25
Navigation System - 9
Front Radar Sensor - 36
Front Side Radar "A" - 17 (Option)
Front Side Radar "B" - 14 (Option)
Blind Spot Monitor "B" - 88
Blind Spot Monitor "A" - 49
Acoustic Vehicle Alerting System - 8 (Hybrid)
Power Integration No.1 - 22
Power Distribution Box - 27
Telematics - 62
*Rear Camera - ?? (Option)
*Digital Rear-View Mirror - ?? (Option)

CdO

Below is the per cell charge curve during a 5.5hr 240V charge (stock EVSE). This curve shape is typical of the NMC/NCM type lithium battery (minus the bits at the beginning and end).

That got me searching around for what kind of batteries these are... long story short... they appear to be Panasonic UF261591TA NCM622 51Ah, 188.7Wh, 3.7V in "PHEV2" form factor. So, 3.7V X 51Ah X 96 = 18.1 kWh. Of course, not all of the energy is usable... in the 450h+ you're out of EV range at ~13.7% and will max out at ~90.6%... that's ~13.8kWh usable for EV (HV will normally stay between 12.1-13.7%; but, you can get down to ~9.6% if you sit idle).



Some details... Of course, the open cell voltage will be lower... at least 30 to... 50+ mV? I massaged the raw data a bit... apparently the car isn't too accurate at calculating the SoC... charge cycles end from ~88% - ~91; then, the SoC resets to ~90.6%. (Update: After a deeper look at the data, I think the car suddenly realized its' % estimation was off and changed its' scaling near the end... the charge rate didn't actually begin to taper off until ~88.4%... not ~87.5%. I also added a projection of the charge curve one would expect if there was no taper... I'll explain why this is useful in a later post.)

The SoC is output with an 8 bit number the software truncates (e.g. 231/255=90.588%; Techstream reports 90.58%; some OBDII devices will read 90.5%); but, it is clear the car has finer resolution internally as some events occur between these values.

For a slight simplification, I used the total pack voltage divided by 96. (This is reported in whole volts... no decimals; the voltage of each cell is reported with three decimals.) I interpolated between the whole volts and interpolated and scaled the SoC to 90.588 as it stopped at 88.23% this cycle. Luckily, I had some hiccups getting started which caused the software to bog down and only measure every ~250ms instead of every ~50ms; so, the graph only has 84,274 data points. (I decided not to bother with the ~12hr 120V log that has almost 900,000 data points.)

CdO

TL;DR: acceleration is dependent upon the battery SoC.

I have seen many comments in various places stating that the full system power is available at all times... this is not true. Of course, if you're interested in 0-60 times... you must consider this. If a tester begins a test at low SoC, the acceleration will be lower.

The car has a value it calls "WOUT Control Limit Power" and "WIN Control Limit Power" i.e. HV battery wattage out/in limit... I have confirmed that the wattage out of the battery does not exceed this limit. The limits are variable depending mostly on SoC; but, they also fluctuate with battery temperature. (In mild temps, the changes are negligible; but, in extremes... IDK.)

The graph below covers the allowed EV Mode SoC range (~13.7 - 90.6% SoC). So, near the end of your allowable EV range your max power is ~80% of maximum. As you might infer from the graph, the max power continues to drop precipitously below this range... to ~62% power at 12.1% SoC (you won't normally go below this level; but, while sitting idle it can go as low as 53% of max).

As you might expect, the maximum power in (charging/regen) begins to taper off dramatically above 80% SoC.


Reference the previous charts above to correlate these numbers to the Lexus App SoC and the number of "bars" in shown in the MID.

mbezzo

Very cool! Thanks for collecting and posting all this!!

drox

Signed up for this forum because of this post, so thank you!

Regarding App SoC vs. Actual SoC. Since Actual is limited between ~13.7% and 90%, I am fine with those being 0% and 100% in the app but they aren't. What is weird is the non-linearity near the bottom of SoC. It's also interesting that the app will say 100% before the Actual SoC is 90%, but it seems to coincide with the percentage that the charging speed drops off...

Also, speaking of charging speed drop-off, it was interesting to see. It really highlights the diminishing returns of time waited for charge after 80%. When using a public charger, especially like those in Ontario which charge based on time, it's probably better to just disconnect and drive home than wait for more charge. I am curious to see if the curve is the exact same with L2 chargers, I understand the graph was made with the stock L1 EVSE.

CdO

Nice to hear, I abandoned the forum/this thread for a while as there didn't seem to be much interest in it. I do have some battery health best charging practices numbers I've been kicking around; but, I am still not sure of the most useful way to present it.

Keep in mind, that 80% is the actual SoC not the App SoC... and the max internal charge rate is actually 50 kW !!! So, even at high SoC the battery can easily accept the full 6.6 kW of the onboard charger (*up to ~87% actual SoC, or ~99% App SoC at ~3 kW... see Note below). Also, that was with the stock EVSE at 240V; so, I believe that technically counts as L2. I will probably log a 6.6 kW charging session at some point; but, any posts with new info here will likely be several weeks from now.

[Note: That tail at the end of the charging session probably shouldn't be like that. I continued my interpolation/extrapolation formulas there when I should have done something different. It seems that is the point where the charge controller switches from constant current to constant voltage charging (or something close to that). It's hard to tell exactly what is going on there as the voltage resolution is relatively poor.]

I was considering taking on the challenge of explaining how they arrive at the total system power; but, this would first require an explanation of how the engine and "eCVT" actually work together/against each other to fully appreciate, so... it's no small task.
Anyone interested?

lsft

Interested and following.

mbezzo

Absolutely!

drox

More data is always great! I am sure there are many lurkers that would love the data as well.

Regarding battery health... I would expect that it would be similar to any other lithium battery. Let it be fully charged for as little as possible, especially at high temperatures.

WeberAuto has an amazing video that explains it pretty well
The video doesn't explain total system power though. Under the hood is a 2.5 liter 4 cylinder naturally aspirated engine with 181 hp, a front electric motor with 179 hp, and a rear electric motor good for 53 hp. How come the total system power is 302 instead of 413?