Expected reliability of LC 250 compared to the GX 550

Wanderlost

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Aug 28, 2023
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Toyota almost certainly uses a numerical event tree analysis to calculate expected and actual vehicle level reliability. Iโ€™m making a list of powertrain components that the GX 550 has but the LC 250 does not and vice-versa. Removing the component from your vehicle also removes the failure probability from your analysis.

Here is my preliminary list of differences:

-The GX 550 has an additional turbo, wastegate controller, intercooler, and intercooler liquid cooling system (including radiator, fan, and water pump).
-The LC 250 does not have an engine cooling system thermostat.
-The LC 250 does not have a serpentine belt.
-The LC 250 does not have an alternator.
-The LC 250 does not have a belt driven AC compressor.
-The LC 250 has a starter motor generator with clutch.
-The LC 250 has a 288 Vdc NiMH battery pack
-The LC 250 has an electrical inverter converter with liquid cooling system including a radiator, fan, and water pump.

One would expect the GX 550 to be more reliable, but the answer may not be as obvious as I thought. My initial impression is the hybrid components could be very reliable. In the end, regulatory efficiency/emissions budgets across all Toyota models probably drove the LC 250 engine selection. Please weigh in with any additions/subtractions/corrections. Hopefully we can gain the attention from someone on the Toyota design team to educate us.
 
Great comparisons, and good points, especially since I am on the cusp of abandoning my LC 250 quest in favor of the GX 550. Some concerns...

-Concerning the GX 550 turbos, can they be serviced without removing the engine or body? With the same system, the Tundra body has to be removed.
-Are we sure the GX 550 has a belt-driven A/C compressor? I would prefer an electric compressor, but the belt-drive rotary compressors have been reliable.
-Are there no belts on the LC 250? Could be mistaken, but it seems I noticed one, albeit not serpentine. If so, what does it drive?
-Good to know the LC 250 hybrid system is 288V. I notice some mild/inline hybrids are 48V, and that would be mild in my opinion. Of course the current relates to power I think, not especially voltage.

I do think the hybrid components will be very reliable, possibly with the exception of the cooling system. Of course the NiMH battery will degrade with time/mileage, but it is still very durable. I much prefer this chemistry over Li-Ion, in particular with the air cooling versus liquid. The clutch/starter system on the LC 250 does concern me a bit, being relatively new. Is it a wet clutch? Do we know for sure if the LC 250 has eliminated the traditional starter? The Tundra has a traditional starter also, for extreme cold weather conditions, and I believe if the hybrid battery becomes excessively low with its charge.

Thinking about it a bit, I think both vehicles will be very reliable. Probably a toss-up.

Great discussion, and the way I shop for vehicles. Hope more input follows!
 
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Concerning electric compressors, are they all with integrated/internal drive motors, or do some employ an "external" drive motor, and a seal is required between the motor and compressor? An internal drive motor would seem the best from a refrigerant leakage standpoint and motor bearing lubrication.
 
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Great comparisons, and good points, especially since I am on the cusp of abandoning my LC 250 quest in favor of the GX 550. Some concerns...

-Concerning the GX 550 turbos, can they be serviced without removing the engine or body? With the same system, the Tundra body has to be removed.
-Are we sure the GX 550 has a belt-driven A/C compressor? I would prefer an electric compressor, but the belt-drive rotary compressors have been reliable.
-Are there no belts on the LC 250? Could be mistaken, but it seems I noticed one, albeit not serpentine. If so, what does it drive?
-Good to know the LC 250 hybrid system is 288V. I notice some mild/inline hybrids are 48V, and that would be mild in my opinion. Of course the current relates to power I think, not especially voltage.

I do think the hybrid components will be very reliable, possibly with the exception of the cooling system. Of course the NiMH battery will degrade with time/mileage, but it is still very durable. I much prefer this chemistry over Li-Ion, in particular with the air cooling versus liquid. The clutch/starter system on the LC 250 does concern me a bit, being relatively new. Is it a wet clutch? Do we know for sure if the LC 250 has eliminated the traditional starter? The Tundra has a traditional starter also, for extreme cold weather conditions, and I believe if the hybrid battery becomes excessively low with its charge.

Thinking about it a bit, I think both vehicles will be very reliable. Probably a toss-up.

Great discussion, and the way I shop for vehicles. Hope more input follows!
Iโ€™m hesitant to generate speculation; there are limited credible sources of information available. This is all best effort on my part.

The GX 550 turbo location may be a compromise for the global architecture volumetric integration; Iโ€™m not sure about access on the GX 550.
The AC compressor is powered by the hybrid system inverter converter on the LC 250, a belt drive is the only other option for non-hybrids.
Iโ€™m highly certain there will not be a serpentine belt on the LC 250 similar to the hybrid turbo V6 in the Tundra. No alternator, electric fans and water pumps, and an inverter converter powered AC compressor.
The LC 250 will have a back up 12v starting system similar to the hybrid Tundra.
The starter motor generator has a wet clutch with a fluid system shared with the transmission; the reliability of the whole unit could potentially be on the order of magnitude equal to an alternator or better. I expect the reliability design requirements for the starter motor generator are equal to the transmission.

I take my Jeep places vehicles only leave under their own power or by helicopter extraction, so reliability is very important for me.
 
I can relate. Owned a Jeep Wrangler once, and traveled to distant/difficult/remote locations in Nevada. However, it wasn't terribly bad. Never left me stranded, but the evap system failed, and it dripped oil from the (split) rear main seal. However, I did like the 4.0 inline six.
 
Iโ€™m still trying to confirm the fully electric driven engine cooling system on the LC 250. It appears Toyota may have used some type of mechanical engine cooling fan with an electric clutch on the Sequoia; Iโ€™m hoping this configuration does not exist on the LC 250.

It appears the engine cooling system on the Sequoia would shut down in traffic under hybrid power if there is a mechanical fan drive. When the engine shuts off in traffic under hybrid power, I would prefer a fully functional engine cooling system actively flowing fluid across the engine as well as the turbo charger.
 
It appears the engine cooling system on the Sequoia would shut down in traffic under hybrid power if there is a mechanical fan drive. When the engine shuts off in traffic under hybrid power, I would prefer a fully functional engine cooling system actively flowing fluid across the engine as well as the turbo charger.
This would be very strange. I could not find a Toyota document but most probably it has electric fan and electric water pump.
 
AMD from โ€œThe Car Care Nutโ€ Youtube channel reviewed the Crown in hybrid max configuration yesterday, and there is a serpentine belt to drive the water pump. This was apparently done for cost control to reduce engine configurations across models. I suppose the serpentine belt only has to last as long as the water pump, and Toyota can restrict shutting down the engine in stop and go driving depending on temperatures. An all electric engine cooling system would have enabled software to change post-shutdown cooling system run-times to solve unforeseen thermal control problems in-service; I will have to try and like this.

It also looks like the inverter will share a liquid cooling system with the turbo which raises the question of the GX550 using the 12v battery to run the turbo liquid cooling system after engine shut-down. Also from AMDโ€™s channel related to the 2023 LX600, it looks like the GX550 may not have the engine cooling distribution active management system from the 2.4L engine, which has me wondering about the reliability of that system.
 
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Great thread @Wanderlost - What would you guess the lifetime of the NiMH battery pack will be?
 
Great thread @Wanderlost - What would you guess the lifetime of the NiMH battery pack will be?
Battery pack replacement will be required once in the life of the vehicle for most owners, or about every ten years. Ambient thermal exposure is a big driver, so Seattle and Phoenix could see variances of several years.

Iโ€™m planning replace the cells (40ea) with new cells before capacity degrades down to 10yr/150,000 mile warranty levels. New cells should be less than $100 each; I would not consider installing reconditioned cells. I have experience with high energy batteries, so I plan to replace the cells myself.

There appears to be an improved bi-polar battery pack with the same NiMH chemistry, this could marginally improve performance across a range of metrics including battery life.
 
On the 2024 Sequoia the hybrid system has 8 yrs 100 000 miles warranty. And the battery 10 yrs 150000 miles. Who knows what batteries will be available in 2034 ?
 
On the 2024 Sequoia the hybrid system has 8 yrs 100 000 miles warranty. And the battery 10 yrs 150000 miles. Who knows what batteries will be available in 2034 ?
The NiMH bipolar architecture required considerable development cost for Toyota, so I expect these to be available at the first battery replacement on the LC 250.

batteries | Toyota Industries Corporation

The NiMH bipolar architecture will replace the current generation NiMH batteries and appears to diminish some advantages of Li-ion chemistries.
 
I was about to post a new thread about the longevity of the hybrid batteries in the new LC. Because once Toyota gets out all the bugs, many people expect even the new LC to last quite a few years, maybe around 15 years if the frame and body is built well.

How much ballpark would a hybrid battery replacement cost? Is it similar to the Prius and other replacements? How much are they At the 10 year mark?
 
I think this is a different story. Toyota was the only player 10-15 years ago. Today there are so many companies involved and huge investments in research.
The batteries will be much better in any aspect 10 years from now.
 
I was about to post a new thread about the longevity of the hybrid batteries in the new LC. Because once Toyota gets out all the bugs, many people expect even the new LC to last quite a few years, maybe around 15 years if the frame and body is built well.

How much ballpark would a hybrid battery replacement cost? Is it similar to the Prius and other replacements? How much are they At the 10 year mark?
Battery replacement cost on the LC250 will be comparable to the Prius with NiMH cells. The LC250 will have around 40 NiMH cells, and my current rough estimate for replacement is $100 per cell with 4 to 8 hours of labor required. Cell replacement will be required approximately every 10 years independent of miles driven. Battery life can be marginally extended by avoiding exposure to hi ambient temperatures, but I expect a 15 year life would be an anomaly.

While fuel consumption will be slightly improved, measuring the value of Toyotaโ€™s parallel hybrid system requires a consideration of the additional torque provided in addition to the normal combustion engine. For reference, the LC250 hybrid motor/generator produces more torque (148 lb-ft) than the engine in my Jeep Wrangler (140 lb-ft) for a total operating battery replacement cost of around $5,000 USD over 20 years of driving. The combined torque of of the LC250 powertrain will be 465 lb-ft.
 
I could not find the torque of the hybrid motor. But, 48 hp is not much. Maybe AMD is right in the Sequoia i-Force MAX video: these are not true "hybrids". The hybrid system is there just for increased power and torque. It means you cannot improve efficiency by driving long time on battery.
 
I could not find the torque of the hybrid motor. But, 48 hp is not much. Maybe AMD is right in the Sequoia i-Force MAX video: these are not true "hybrids". The hybrid system is there just for increased power and torque. It means you cannot improve efficiency by driving long time on battery.
Having driven the new Sequoia, I can tell you that mild hybrid drivetrain provides far more low-end torque than one reasonably needs. But, it's a ponderous SUV. My hope is that the mild hybrid for the LC250 is of similar effect. Getting a fraction of the pep of the Sequoia in a more right-sized LC250 could be a lot of fun.
 
Mild Hybrid is a different system. Small battery and small electric motor.
A new Mild Hybrid model is Mazda CX-60 (a smaller CX-90) 3.3L Inline 6 Diesel.
Battery: 48V 0.33 kWh. I mention this car because it can provide an amazing efficiency. I tested it for about one hour (city and highway).
and got 65 mpg.

"Mild hybrids (MHEV) (also known as power-assist hybrids, battery-assisted hybrid vehicles or BAHVs) are generally cars with an internal combustion engine (ICE) equipped with a negligibly bigger electric combined motor and generator in a parallel hybrid configuration allowing the engine to be turned off whenever the car is coasting, braking, or stopped, and then quickly restarted once power is again required. Mild hybrids may employ regenerative braking and some level of power assist to the internal combustion engine, but mild hybrids do not have an electric-only mode of propulsion."
 
Mild Hybrid is a different system. Small battery and small electric motor.
A new Mild Hybrid model is Mazda CX-60 (a smaller CX-90) 3.3L Inline 6 Diesel.
Battery: 48V 0.33 kWh. I mention this car because it can provide an amazing efficiency. I tested it for about one hour (city and highway).
and got 65 mpg.

"Mild hybrids (MHEV) (also known as power-assist hybrids, battery-assisted hybrid vehicles or BAHVs) are generally cars with an internal combustion engine (ICE) equipped with a negligibly bigger electric combined motor and generator in a parallel hybrid configuration allowing the engine to be turned off whenever the car is coasting, braking, or stopped, and then quickly restarted once power is again required. Mild hybrids may employ regenerative braking and some level of power assist to the internal combustion engine, but mild hybrids do not have an electric-only mode of propulsion."
Appreciate the explanation.
 
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