[Tom E-Tron]

Lyric sales for Q4 were 86 and I think Hummer was 85. How is that priority?

Edit - Hummer sales for Q4 was 72, still not far off the low Lyric number.

Bill, this guy is an idiot.... Everything he says is wrong (or pure speculation), like where he said they are starting with high spec Lyriq and Silverado E, wrong on both counts, Lyriq started with the base model RWD, and Silverado E is starting with the WT (Work Truck) model, Higher end versions of both models are coming later.

 

[Tom E-Tron]

The stock hasn't done anything in five years -

View attachment 3847

GM stock has risen since Q4 numbers were announced, even with low sales of Hummer and Lyriq, it was just another point you had wrong...

GM stock set all time highs last year in early January, with only 1 Hummer delivered. In case you have not noticed, there are Macro events placing pressure on all auto stocks in the last year. In that time, Tesla down, way more than GM, even though their sales are up. Elon Musk the first person in history to lose $200B of net worth

 

[Carac]

Long-term trends coming to roost and being reflected in recent pricing as well. Demand for GM's EVs is currently (and literally) insatiable. Consumer research into Tesla's brand image and enthusiasm has demand for their cars in decline and dropping off a cliff when current orders are satisfied in 6-9 months. The Model 3/Y did great when you didn't have the Ioniq 5, Mach E, Kia EV6, VW ID4, etc. There are a LOT of attractive alternatives already here and on the way. I said it in the other thread. There's nothing really "new" on Tesla's radar, they've just been iterating on the same cars while their competition is already showing off the next half decade of new product. The Cybertruck is vaporware so far. They have a barely functioning prototype they keep rolling out to go viral on social media every once in a while. There hasn't been hide nor hair of the Roadster. Next-gen S, 3, X, and Y models are 5+ years or more away. They're treading water while everyone else is surfing. Once GM and others get some traction it's going to be ever uglier for Tesla. You'll have better built cars with near tech parity at competitive pricing. GM is just trying to get over some speed bumps and we're all impatient, especially me.

 

[azbill]

GM has probably been smart to slow the rollout of the Ultium EVs. Better to fix issues on fewer vehicles, rather than running up warranty costs. Ford has rolled out their EVs faster, but at a significant cost:

Ford CEO Farley tells retired engineers fixing quality will 'take several years'

Ford CEO Jim Farley tells retired Ford engineers that quality is the #1 priority but will take several years to fix.

www.autoblog.com

 

[HVACman]

Wrong... Hummer has some engineering problems they are working through is the reason sales have been low. I have been talking to GM executives daily for the last 3 weeks about my Hummer EV, I know what is going on...

I'm wondering if, besides the pack water leakage issue, one other post-delivery Hummer/BT1 platform engineering problem worth suspending further deliveries is the 800 volt fast-charging situation. The pack-switching and weird charging speed oscillations was wreaking havoc with even the most experienced EV-journalists' fast charge analyses and creating some very-negative publicity. Definitely something to address with a better solution before the Silverado EV starts full production. And that solution likely will require a hardware change as well as software, which would also would mean remove/replace packs, as the switching contactors, etc are all inside the pack housing.

 

[Tom E-Tron]

I'm wondering if, besides the pack water leakage issue, one other post-delivery Hummer/BT1 platform engineering problem worth suspending further deliveries is the 800 volt fast-charging situation. The pack-switching and weird charging speed oscillations was wreaking havoc with even the most experienced EV-journalists' fast charge analyses and creating some very-negative publicity. Definitely something to address with a better solution before the Silverado EV starts full production. And that solution likely will require a hardware change as well as software, which would also would mean remove/replace packs, as the switching contactors, etc are all inside the pack housing.

I have not heard anything specific to that issue,

 

[azbill]

I'm wondering if, besides the pack water leakage issue, one other post-delivery Hummer/BT1 platform engineering problem worth suspending further deliveries is the 800 volt fast-charging situation. The pack-switching and weird charging speed oscillations was wreaking havoc with even the most experienced EV-journalists' fast charge analyses and creating some very-negative publicity. Definitely something to address with a better solution before the Silverado EV starts full production. And that solution likely will require a hardware change as well as software, which would also would mean remove/replace packs, as the switching contactors, etc are all inside the pack housing.

I think that issue is all about software. The hardware solution would be to go 800V full time, or to add an 800 to 400 converter to the HVAC. The latter could be done external to the battery. A pure 800V would require motor changes.

 

[Dark-Fx]

I think that issue is all about software. The hardware solution would be to go 800V full time, or to add an 800 to 400 converter to the HVAC. The latter could be done external to the battery. A pure 800V would require motor changes.

If the pack splitting issue really is what has been suggested, I am surprised that their BMS doesn't have the capability to keep balance between the two halves when they are put into series.

 

[azbill]

If the pack splitting issue really is what has been suggested, I am surprised that their BMS doesn't have the capability to keep balance between the two halves when they are put into series.

The switching is for the HVAC system, it only runs on 400V, so one pack has more load (higher resistance) than the other one. Since each half is >100kwh, it would take a huge resistor to balance the packs, it would have to have the same load as the HVAC system load. That would also waste energy and make the charging less efficient.

If the two packs get switched back into parallel with a different voltage, it can create a huge in-rush current. There is a balancing resistor to do that prior to connecting, but that requires that the voltage split be kept under some limit. What they are doing, based on the patent, is switching the HVAC load when the voltage difference between the halves exceeds some threshold.

Ideally, if the HVAC could run on 800V or 400V, then this issue would not exist.

 

[HVACman]

The switching is for the HVAC system, it only runs on 400V, so one pack has more load (higher resistance) than the other one. Since each half is >100kwh, it would take a huge resistor to balance the packs, it would have to have the same load as the HVAC system load. That would also waste energy and make the charging less efficient.

If the two packs get switched back into parallel with a different voltage, it can create a huge in-rush current. There is a balancing resistor to do that prior to connecting, but that requires that the voltage split be kept under some limit. What they are doing, based on the patent, is switching the HVAC load when the voltage difference between the halves exceeds some threshold.

Ideally, if the HVAC could run on 800V or 400V, then this issue would not exist.

I've attached a very rough schematic of the two scenarios below that shows how the amps flow and illustrates the inherent amp charging imbalance issue between the sub-packs at 800 VDC. This assumes about 6-7 kW total 400 VDC load to run the compressors + DC-DC converter.

It is more than just the compressor, though, that requires 400 VDC. all the processors, the fans, the pumps, all sorts of stuff run on 12 VDC, which requires power from the 400 VDC-12 VDC power supply. It is extremely difficult to come up with a continuous way of bleeding down the excess amps going to sub-pack 1, as that would required dissipating 20 amps, which would be 6-7 kW of heat to get rid of, in addition to the 15-20 kW of pack heat already being generated. The little resistors or transistors in the BMS balancing circuits work at watts and milli-amp levels, not kW. Sub-pack switching is about the only way, but it would be nice if GM could find a way to make the switching both smoother and faster so it is more momentary rather than a multi-minute pause.

 

[Dark-Fx]

The switching is for the HVAC system, it only runs on 400V, so one pack has more load (higher resistance) than the other one. Since each half is >100kwh, it would take a huge resistor to balance the packs, it would have to have the same load as the HVAC system load. That would also waste energy and make the charging less efficient.

Ew no, you use a DC-DC system for this. Could be close to 99% efficient.

 

[azbill]

Ew no, you use a DC-DC system for this. Could be close to 99% efficient.

I agree, adding a DC-DC to run the HVAC and 12V from 800V would solve the issue. I mentioned that in Post #27. There is already a 400V to 12V converter on board.

There is still an outlier case though, that if the two packs in series get too far out of balance, they would have to switch back to 400V with a short time to balance them before going parallel. But that woudl be OK once the pack gets to higher SoC levels and is below 200kw charging level.

 

[HVACman]

I agree, adding a DC-DC to run the HVAC and 12V from 800V would solve the issue. I mentioned that in Post #27. There is already a 400V to 12V converter on board.

There is still an outlier case though, that if the two packs in series get too far out of balance, they would have to switch back to 400V with a short time to balance them before going parallel. But that woudl be OK once the pack gets to higher SoC levels and is below 200kw charging level.

Conceptually, yes, a 800/400 V DC-DC stepdown, rated at 6-8 kW would be a solution. This DC-DC unit would be more complex than the existing 400/12 step-down DC-DC, as it is a higher kW rating and would cost more $$, as it requires SiC MosFETs for handling 800V, plus additional glycol cooling connections, etc. Also, this would not be a small device. There is a lot of that the HV management stuff already inside the nose of the pack in that slight push-out and/or tagged onto the rear DU.. This would probably have to fit externally in a crowded back-end between the DU and the pack.

It might be that the sub-packs could be dynamically maintained in-balance if there was a 400 V connection between the lower-voltage sub-pack + and the + output of the new DC-DC. By tweaking the DC-DC voltage output, the BMS cold either "inject" a few amps from the DC-DC output into the sub-pack or draw a few amps from sub-pack to feed the 400 V loads. This would eliminate the issue of pack switching completely, since this allows the BMS to manage each pack's voltage and SOC independently while 800 V charging, regardless of 400 V loads or the relative health of each sub-pack.

 

[azbill]

Conceptually, yes, a 800/400 V DC-DC stepdown, rated at 6-8 kW would be a solution. This DC-DC unit would be more complex than the existing 400/12 step-down DC-DC, as it is a higher kW rating and would cost more $$, as it requires SiC MosFETs for handling 800V, plus additional glycol cooling connections, etc. Also, this would not be a small device. There is a lot of that the HV management stuff already inside the nose of the pack in that slight push-out and/or tagged onto the rear DU.. This would probably have to fit externally in a crowded back-end between the DU and the pack.

It might be that the sub-packs could be dynamically maintained in-balance if there was a 400 V connection between the lower-voltage sub-pack + and the + output of the new DC-DC. By tweaking the DC-DC voltage output, the BMS cold either "inject" a few amps from the DC-DC output into the sub-pack or draw a few amps from sub-pack to feed the 400 V loads. This would eliminate the issue of pack switching completely, since this allows the BMS to manage each pack's voltage and SOC independently while 800 V charging, regardless of 400 V loads or the relative health of each sub-pack.



View attachment 3855

Do you know any of the specs for the Ultium cells/modules? I have Simscape Battery and can build a model of this.

 

[azbill]

It might be that the sub-packs could be dynamically maintained in-balance if there was a 400 V connection between the lower-voltage sub-pack + and the + output of the new DC-DC. By tweaking the DC-DC voltage output, the BMS cold either "inject" a few amps from the DC-DC output into the sub-pack or draw a few amps from sub-pack to feed the 400 V loads.

Actually there is an existing way to dynamically balance the two packs. Each pack, according to the patent, still has at least one inverter/motor connected to it. The pack not connected to the HVAC could simply dump some current through the motor to balance the load. That would waste some energy as heat decreasing efficiency. The parking brake is already set when fast charging.

I also think that at some point they would need to switch to 400V, maybe at say 100-150kw power level, that would keep the balancing perfect with better efficiency when the battery is at higher SoC. In fact, there has already been records of the pack dipping at around 70-80% SoC, then ramping back up. I am willing to bet they are going to 400V at that point. The HVAC load will have a much higher effect on imbalance when charging at lower power. Someone with a truck could test for that on one of the newer EVGO Signet chargers, they show voltage on the screens.

 

[KITT]

 

[Dark-Fx]

https://jalopnik.com/cadillac-says-slow-lyriq-deliveries-are-all-part-of-its-1849974226

 

[HVACman]

Actually there is an existing way to dynamically balance the two packs. Each pack, according to the patent, still has at least one inverter/motor connected to it. The pack not connected to the HVAC could simply dump some current through the motor to balance the load. That would waste some energy as heat decreasing efficiency. The parking brake is already set when fast charging.

I also think that at some point they would need to switch to 400V, maybe at say 100-150kw power level, that would keep the balancing perfect with better efficiency when the battery is at higher SoC. In fact, there has already been records of the pack dipping at around 70-80% SoC, then ramping back up. I am willing to bet they are going to 400V at that point. The HVAC load will have a much higher effect on imbalance when charging at lower power. Someone with a truck could test for that on one of the newer EVGO Signet chargers, they show voltage on the screens.

re: using inverter/motor. I missed that aspect in the patent. Thanks for pointing it out. The problem with that solution is what to do with the extra waste glycol heat. You've got the glycol chiller already in full-on cooling mode keeping the battery cool...probably 15 kW or so. Lay on 5 more kW of waste heat in the glycol loop....it might be that the 4-way valve could send the hot DU glycol directly to the radiator and not interfere with the chilled glycol flow going to the battery, but I'm getting beyond my pay-grade with further speculation

That technique probably is using the same "trick" Tesla does with their drive units to create heat for heating the battery or providing heat to the heat pump. Tesla feeds a few kW of DC power through the inverter power transistors, which throttles down the voltage through current flowing to the windings and creates a lot of resistance heat, both at the inverter and in the windings. If the power transistord are just driven to "throttle" mode and not "on/off" pulse-width modulated mode, they don't create any AC and there is no rotating stator magnetic field. The motors don't create any torque, so locking the wheels isn't that big of a deal.

re: switching back to 400 VDC at high SOC's. Yes, I bet it does do that, as that allows a full balance at the later stages. Yes, data with amps + volts for a full charge session would be nice. Memo to...everyone.

Nothing like arm-chair engineering I don't know what, if anything, GM's battery engineers are doing to improve the 400/800 volt charging situation so it doesn't act so weird, but I can't help but think they have something in the works. I'd hate to see ongoing reviews when the Silverado rolls out like Tom and Kyle's charge-session Hummer reviews, and I suspect GM would hate to see that, too.

 

[H3X]

https://jalopnik.com/cadillac-says-slow-lyriq-deliveries-are-all-part-of-its-1849974226

Ahem, my prediction of Lyriq deliveries eclipsing Hummer EV deliveries in 2023 Q1 is trending towards becoming reality - How is GM able to make huge batteries and still keep the...

The supposed Insider was the one who was wrong - How is GM able to make huge batteries and still keep the...

Here's a prediction to clarify the Silverado EV point - the Silverado EV will outsell the Hummer EV for total 2023 deliveries. The per unit economics (profit) are higher for the Silverado EV than the Hummer EV (duh), hence they are allocating more batteries/production time @ Hamtramck for the Silverado EV.

Prediction - Bolt (shouldn't even really count, but whatever), Lyriq, Silverado, Hummer - highest to lowest 2023 EV deliveries. If you subtract the Bolt, I'll go with a combined 40K deliveries amongst the other three models for all of 2023.

The Blazer and Equinox will sell, combined, less than 500 units in 2023.

 

[Nebula1701]

The Quality Hold on the Lyriq just ended, GM is in the process of shipping out some 500 Lyriqs to dealerships right now.

People following the car sites and on the facebook pages are seeing a massive influx of Lyriq deliveries.