Fusion Hybrid Powertrain Technical Analysis with Torque Pro & a ScanGauge

[hybridbear]

As many of you know, I am very interested in understanding how the car works. For that purpose I bought a ScanGauge last summer and recently purchased a cheap Android tablet from Amazon and a Wi-Fi ELM 327 scanner to communicate with the tablet and Torque Pro app. The tablet setup is not very useful to look at data while moving to adjust my driving style, but it is very useful to log data to analyze offline. The ScanGauge does not log data to be able to analyze after the fact. I also bought a splitter cable so that I could use both the ScanGauge and the tablet at once, but they don't work together in the Fusion. In the Prius I can use both devices at the same time. Special thanks to larryh for explaining many things to me and getting me setup!

I am going to use this thread as my overall summary of everything that I have learned about the FFH powertrain operation to date. I will also continue to post future knowledge gained in this thread.

ICE Operation Observations

• Horsepower - the generator often places about a 15 horsepower load on the ICE when the battery is low and the ICE is doing maximum recharging. This is good for about 35 amps of current flowing into the HVB. In other situations it seems that each hp of ICE output to spin the generator is good for slightly less than 2 amps of current flowing into the HVB. In these situations the Generator Torque is consistently about 30 newton-meters. Torque shows this torque as a negative number. I think that's the unit of my data at least. Unfortunately, I don't have a way to track HP with Torque (just LOD) so I cannot calculate how much of each HP of engine output becomes 1 kW of electricity generated unless someone else can see something that I'm missing that would allow me to do so.
• With the ScanGauge II two of the most useful gauges I've found are the Horsepower and LOD (Load) gauges. Below is a BSFC chart for the 2nd Gen Prius (1.5L engine) and 3rd (current) Gen Prius (1.8L engine). BSFC = Brake Specific Fuel Consumption. If you aren't familiar with what that means you can read more here. Do take the time to read the explanation. Understanding this concept is crucial to maximizing your fuel economy.
  
  
  
  Notice how the Prius is most efficient, a low g/kWh, at a fairly high power (kW) output but a low engine speed (less than 3650 RPM). To get such a high power output a such a low speed the computer must be placing a high load on the engine. As described in the link above, in a normal gas car you're often operating at only about 25% throttle which is a light load on the engine. In the hybrid, the generator places a load on the ICE to increase the load and get the car to run in a more efficient BSFC region. For the Prius, which has a smaller engine, the kW output is a maximum of about 30 kW in the peak BSFC region. 30 kW = 22.37 hp. That isn't a lot of power demand. Unfortunately I don't have a BSFC graph for the FFH 2.0L engine. However, based on my observations of hp and LOD readings on my ScanGauge I have a pretty good idea where it is...When the FFH SGII output shows 33-42 HP (24.6-31.3) I have observed a LOD of 95+. This is typically a 2 bar acceleration on the Empower screen. The FFH acceleration coach considers this to be efficient and returns the maximum score on the acceleration coach bar. If I accelerate more slowly, I only see LOD numbers in the low seventies to low eighties. When accelerating harder than this I still see a high nineties LOD but the ICE is too far off to the right on the graph and is out of the most efficient range. This leads me to believe that the peak BSFC region for the Ford 2.0L Atkinson-cycle engine is somewhere around 20-35 kW of power. I have asked Ashley a few BSFC related questions and have been told that this info is proprietary and that Ford will not share that info with me.
• Warm up stages - when the ICE is in S1a the power demand on the ICE is very low, less than 10 hp and a LOD less than 60, this is quite inefficient and shows why skipping stage S1a improves fuel economy so much as discussed here.
• Transmission/battery storage efficiency appears to be about 95% when the ICE is generating electricity. I will continue to calculate more data for this as I have time to confirm the 95% efficiency and to check if other factors affect that efficiency. For example, Torque allows me to log the amps and volts at 1 second intervals. During a prolonged stretch of ICE on HVB charging I used the amps and volts from Torque to calculate the kW generated each second. I then converted this to kWh. Then I summed the kWh from my second-by-second calculations of kWh - ((amps x volts)/1000)/3600. I then looked at the percent change in absolute SOC according to Torque/ScanGauge. The car displays this data to 8 decimal places on the Torque app, this is very precise data. I took that delta in SOC and multiplied it times 1.4 since that's the kWh capacity of the pack. Then I could compare the data. Here is a set of sample calculations:

kWh used SOC change SOC calc kWh Efficiency
0.10368587 7.78199768 0.108947968 95.170%


EV Operation Observations

• Amps - the maximum regen braking charge seems to be about 65-70 amps. I've never seen the regen braking charge go above 75 amps while still getting 100% brake score. That seems to be the limit for using the traction motor as a generator (when braking the traction motor recharges the battery, when the ICE is charging the battery the electricity is generated by the generator motor). When driving in EV 1 bar on the Empower screen is about 40 amps of current flowing out of the battery. The max current I have seen flowing out of the battery has been about 110 amps. This happened when I was accelerating in EV at 1.5 or 1.75 bars and then it kicked over to the ICE. Since one motor/generator must spin the ICE up to speed (like a starter motor in a conventional car) there is a momentary spike in amps flowing out of the battery to start the ICE. There is also a momentary positive value of Generator Torque of about 18-21 newton-meters right when spinning the ICE up to speed.
• Recharging - The computer likes to charge the battery with a ~30 amp current flow when the battery SOC is low to maybe about 75% of the display. This seems to be in the most efficient range of the ICE as well as the LOD will often be 85+ when this load is placed on the ICE by the generator while accelerating. When the battery SOC is higher than 75% of the battery icon the amps from the ICE generator drops to 10-20 amps. If the battery is almost full the current flow drops to about 5 amps. Note: the car will aggressively charge the HVB if the useable SOC is less than 40%. From 40-50% useable SOC it will slowly charge the HVB as mentioned above.
• Coasting - when coasting with your foot off the gas pedal the generator places about a 5-10 amp load to gradually slow the car down.
• Idling - when idling the current draw to run the computers and charge the 12V battery is about 1.1-1.2 amps. This amount of current is drawn whether the car is in Park, Reverse, Neutral or Drive as long as you are not moving. The brake lights pull a minimal amount of current, but enough to make this range 1.2-1.3 amps when you are stepping on the brake.
• Lights - the headlights/taillights draw about 0.5 amps (140 watts). The park lights and fog lights draw the same amperage as the headlights. If you combine headlights and fog lights the current draw is about 0.9 amps (260 watts). This means that the headlights and fog lights each draw about 0.4 amps (110 watts) and the park lights draw about 0.1 amps (28 watts)
• Current draw when off - after turning off the car in the few seconds before the SGII turns off the power draw shows 0.08 amps. This is likely to run whatever computers are still active to display the Trip Summary and Lifetime Summary screens.
• Battery display on dash without charge/discharge arrows - It is very hard to get the battery display to show no arrows for charging or discharging. It appears that while moving the car displays no arrows when the current flow is less than 2 amps in or out of the HVB. However, sometimes the current flow will be less than 2 amps and the dash will still display arrows for charging or discharging. Also, when stopped a current flow of less than 2 amps displays as the HVB is discharging. No matter how hard I've tried I have never been able to get the display to show 0.00 amps as the current flow. With steady pedal pressure it is possible to keep the amp flow steady for many seconds though while driving as long as the slope of the road doesn't change.

High Voltage Battery Pack Observations

• HVB temps - the HVB temp quickly increases when driving from the current flow in and out of the battery. In the winter, the HVB fans kick on when the HVB exceeds 70^oF. The fans will stay on even when the HVB temp drops as low as 68^oF. I haven't had any trips where the HVB temp has gone above 70 to trigger the fans and has then dropped lower than 68 with the fans operational to see if the fans will shut back off.
• It seems that the useable SOC will jump around when the HVB temp changes while the car is off. If the HVB cools then the useable SOC jumps. If the HVB temp rises from having been cold, the SOC seems to fall.
• The max power limit for the HVB is normally 35 kW. When the battery is very cold this drops. This also appears to drop when the HVB is very warm, but I don't have hard data to support this. This post shows data that an Energi owner gathered. The FFH should roughly compare.
• AC amp draw - the AC will draw 30-40 amps from the HVB when first turned on with a hot car. Once the car has cooled down the AC continues to draw an extra 4-7 amps minimum that we observed. This puts some numbers to the effect of AC on gas mileage. That is a lot of current that must be replaced by burning gasoline. 30-40 amps is roughly 8.4-11.2 kW of power draw to run the AC at first. This is a huge power draw.
• HVB Volts vary from 255-305 in my observations. Low voltages happen when the HVB is discharging and at a lower SOC. Higher voltages happen when the HVB is being charged and the SOC is higher. Volts are most commonly 280-290 and I typically use these numbers in my calculations.
• The battery icon on the dash is not linear. A 75% useable SOC equates to a battery icon that is ~8/10-9/10 full. A 60% useable SOC equates to a battery icon that is roughly 2/3 full. A 40% useable SOC equates to a 1/2 full battery icon. And a 20% useable SOC equates to a battery icon that is roughly 1/4 full. The 5% useable SOC that triggers the ICE to run and charge the battery while idling appears as roughly 1/8 full on the dash icon.
• The battery icon displays a rough estimate of the useable SOC of the battery. You can convert the useable SOC to the absolute SOC since the ScanGauge/Torque apps will allow you to access both data points. The linear equation is: y = 0.3837x + 0.312. y is the overall SOC and x is the useable SOC. This provides us some interesting data:
• The intercept is 31.2%, this means that if the useable SOC showed 0% the actual battery SOC would be 31.2%
• If we plug in 100% for x we get a result of 69.57% (0.3837 x 1 + 0.312)
• When idling the car will not let the useable SOC drop below 5% (33.12% absolute SOC) before turning on the ICE to charge the HVB. The ICE will run until the useable SOC reaches 30% before turning off again
• This means the limits for HVB charge are 33.12% and 69.57%
• Since the car doesn't really allow the useable SOC to go much below 15% and doesn't often let it go much above 60% we can see that in normal driving the range is 36.96%-54.22%
• However, most trips don't see the useable SOC get as low as 15%, it's very hard to keep the car in EV mode once the useable SOC gets below 20% unless you're cruising on flat ground at low speeds with a minimal power demand. A typical useable SOC range while driving is 20-60%, this equates to 38.87%-54.22%
• The r² is 0.998 indicating that the linear trend line is very accurate.
  

Power Flow Screen Observations

• Charging HV Battery
  
  
  Here you have blue flow from the electric motor to the battery. There is also blue flow from the electric motor to drive. There is white flow from fuel to engine to drive and from engine to electric motor. This seems to be one of the most common powertrain options chosen by the FFH computers. This screen often shows when traveling at highway speeds. In this mode both the Generator & the Traction Motor are consuming mechanical energy from the ICE and are sending electrical energy to the HVB. In this mode the wheels are only receiving power from the ICE.
• Hybrid Drive

In this case the HVB is also often being charged. When the HVB is being charged in Hybrid Drive the Generator is consuming mechanical energy and is converting it to electrical energy. Some of that electric energy is then consumed by the Traction Motor and converted back into Mechanical Energy to propel the car. The remaining electrical energy is sent to the HVB

Sometimes the HVB is not being charged when in Hybrid Drive. Most often this occurs on the freeway when the HVB reaches a high level of charge. Sometimes the Traction Motor consumes mechanical energy and converts it to electric energy, then the Generator consumes electrical energy and converts it to mechanical energy to assist the ICE is propelling the car.

Grille Cover Observations

• With 100% grille blocking and ambient temps below 20 degrees F I see that the coolant temp peaks at 185 F, Motor Inverter Coolant temp peaks at 120 F and Generator Inverter Coolant temp peaks at 140 F. These peak temps have been very consistent. I have never seen temps exceed the aforementioned values with 100% grille blocking. Highway driving generally keeps the Inverter temp between 100 F and 130 F (it cools to 100 F when driving short stretches of EV mode and then spikes quickly when the ICE is on and charging the battery). The Motor temp seems to usually hover between 100 F and 110 F when driving long freeway stretches. In city driving the Inverter temp quickly falls to the 60s or 70s since the ICE runs less and thus the generator does less work. In the city the Motor temp tends to be higher than the Inverter temp since the Motor is doing more work. Long stretches of city driving seem to keep the Motor temp between 65 F and 80 F. Regen braking causes the biggest spike in Motor temp, much more than accelerating in EV causes the temp to spike.
• As the weather warms I will slowly increase the air flow into the engine compartment to monitor these temps. These temps were a concern about grille covers prior. Now I am not concerned because I expect that temps will be much hotter in the summer with 0% grille blocking than they are now.
• As the weather has warmed the grille blocking has led to coolant temps exceeding 200 F. The peak I have observed has been about 230 F. This is still right at the midpoint of the temp gauge on MyView. The temp gauge is no higher with a coolant temp of 230 F compared to 180 F. This tells me that 230 F is a good operating temp. I will slowly begin removing foam now with increasing ambient temps and will report back.

Edited May 19, 2014 by hybridbear

[hybridbear]

Reserved for future use. I will post the XGauge codes and Torque PIDs that I use in this space.

Edited March 10, 2014 by hybridbear

[hybridbear]

I updated the first post to fix a handful of typing errors and to add watts in addition to amps where showing watts better helps to make the data understandable.

[lolder]

Very nice post. Is the transmission/battery 95% storage efficiency just the HVB in/out efficiency or the total gen-charg-discharge-motor loss? I guess it's just the HVB. With 5% for each the gen and motor that would be a total of 15-20% including the gears. The Gen 1 FFH was rumored to have a total EV loss of about 30%. More total EV efficiency raises the balance point speed between EV and ICE. The low BSFC zone in the FFH is probably 1500-2500 rpm..

[hybridbear]

Very nice post. Is the transmission/battery 95% storage efficiency just the HVB in/out efficiency or the total gen-charg-discharge-motor loss? I guess it's just the HVB. With 5% for each the gen and motor that would be a total of 15-20% including the gears. The Gen 1 FFH was rumored to have a total EV loss of about 30%. More total EV efficiency raises the balance point speed between EV and ICE. The low BSFC zone in the FFH is probably 1500-2500 rpm..

Thank you! I need to revisit those numbers. Larryh e-mailed me and it appears that I might have made a mistake in my data analysis. I need to look at more data from a variety of trips to try to get better info. The best BSFC region seems to be from 1900-2200 RPM based on how the computer chooses to run the ICE that I see.

Edited March 11, 2014 by hybridbear

[GrySql]

I admire the work you're doing and the time/money you spend doing it.

[Waldo]

I think it's worth emphasizing that operating a gas engine in it's BSFC "sweet spot" is the entire point of a hybrid powertrain. Other than the regen energy, the BSFC optimization possible with a hybrid is the only reason it gets better fuel mileage than a conventional vehicle.

 

The problem of course is that operating in the BSFC "sweet spot" produces a very narrow range of power. Sometimes you need more, sometimes you need less. The hybrid components are what take that extra energy when you need less and save it for those times when you need more.

[Silver Bullet]

Hybridbear, I just want to express my thanks for the impressive analysis you are doing on how our FFH's work and what it takes to optimizetheir performance.

We only acquired our 2014 FFHSE on Christmas Eve last, and my wife and I both continue to to drive just as we did with our ICE predecessors, but I truly value a source of better understanding this fascinating new machine.

Please continue to share the results of your interesting efforts.

[lolder]

Another fact is an Atkinson cycle ICE with lower BSFC can be used at near wide open throttle most of the time. By the way, in post #1, Fig.3 above, the solid upper lines is where the engines actually run almost all the time. When less power is needed, they go into EV mode. They never run at less than 1000-1100 prm. They only get off the line and out of the low BSFC zones briefly when the power demands change. That's why it's important to have a steady foot on the pedal.

Edited March 15, 2014 by lolder

[hybridbear]

Thanks for the thanks ;)

 

DTC codes P0BCD and P0AF0 indicate that the Generator Inverter and Motor Inverter have gotten too hot. Those codes will not register until 253F (123C). Thus I am completely not concerned about the Generator Inverter temp reaching 140F with grille covers in winter. If Ford doesn't feel that these components are overheating and need to be restricted until 253F, 140F should be no problem.

[kbailey990]

Like many of our members, I am very interested but I lack some of the technical background. Can you elaborate on BSFC and add it to the acronym list? Also, I'd love to learn more about Adkison ICE vs traditional (and I'd be happy to google these if it's any trouble at all)

[lolder]

Like many of our members, I am very interested but I lack some of the technical background. Can you elaborate on BSFC and add it to the acronym list? Also, I'd love to learn more about Adkison ICE vs traditional (and I'd be happy to google these if it's any trouble at all)

BSFC is Brake Specific Fuel Consumption and is a measure of the efficiency of ICE's and a way to compare them. It may be expressed as grams of fuel per kilowatt-hour or other dimensions. See here: http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption.

The Prius fuel map graph figure 3 in post #1 is a quick study. The solid curvey lines denote engine operating zones with the BSFC labeled. The lowest are the best and are 220-230 g/kwh. The vertical axis is torque which equates with throttle plate oprning in a gas engine and the horizontal axis is rpm. The curvey dotted lines are power output which is the product of torque X RPM. It is desired to run the engine only in the shaded zones ON the upper solid line which is about full throttle ( plate opening ). Throttle plate position is not a function of your foot on the go pedal but is controlled by the computer. When you call for more power, the RPM is increased and a transient burst of EV power is added for quicker response. The upper left corner of the solid lines is the minimum power at which the engines are run and this is about 10 KW or 13 hp. That's why the EV cycles at lower speeds. When the HVB SOC gets low in EV, the ICE starts and generator load to raise the SOC is added to the power required to move the car so that the operating point of the ICE is on that solid line in a low BSFC zone.

The Atkinson cycle is a slightly different cycle from the Otto thermal operation of a gasoline ICE. It is arount 8% more efficient. The theory is that the compression stroke is shorter than the power stroke which yields greater thermal ( fuel efficiency ). The first Atkinson engines of over 100 years ago had a second rotating shaft that was connected to an articulating connecting rod to accomplish this feat. They were never practical. The modern Atkinson's which are used in most hybrids are pseudo-Atkinsons as they accomplish the same thermal cycle by closing the intake valve much later in the compression stroke. That's why the intakes are noisy as charge is blown back into the intake manifold and that creates the "growl". Atkinsons have less torque and power per cubic inch than Otto's ( most other cars ) but in a hybrid that is assisted by the electric motors so it's a complementary, co-operative marriage.

Hybrid ICE's are always run at high throttle ( plate ) settings and low rpm just shy of the "bucking" that you could get in too high a gear with manual transmissions. See here:http://en.wikipedia.org/wiki/Atkinson_cycle

Edited March 15, 2014 by lolder

[hybridbear]

The 140 F Generator Inverter temp seems to trigger a change in that cooling system loop because the temp never rises above 140 F even if I continue driving with the ICE on and the generator working to charge the HVB. It appears that when the temp hits 140 F, coolant begins flowing more quickly or coolant begins circulating through the radiator when prior to that it wasn't. When the Gen Inverter temp hits 140 F, the temps of both it and the Motor Inverter begin to quickly drop, even if I'm continuing to drive in a way that would normally make them heat up. Further evidence that grille covers don't adversely impact the hybrid components.

[GrySql]

I wish I could give more than just one 'Like' to some of these excellent posts.

[larryh]

 

ICE Operation Observations

 

Unfortunately I don't have a BSFC graph for the FFH 2.0L engine. However, based on my observations of hp and LOD readings on my ScanGauge I have a pretty good idea where it is...When the FFH SGII output shows 33-42 HP (24.6-31.3) I have observed a LOD of 95+. This is typically a 2 bar acceleration on the Empower screen. The FFH acceleration coach considers this to be efficient and returns the maximum score on the acceleration coach bar. If I accelerate more slowly, I only see LOD numbers in the low seventies to low eighties. When accelerating harder than this I still see a high nineties LOD but the ICE is too far off to the right on the graph and is out of the most efficient range. This leads me to believe that the peak BSFC region for the Ford 2.0L Atkinson-cycle engine is somewhere around 20-35 kW of power. I have asked Ashley a few BSFC related questions and have been told that this info is proprietary and that Ford will not share that info with me.

 

I think you can create a chart very similar to a BSFC chart using the OBD II data from the FFH, but it will take a lot of work. I am not expert on internal combustion engines, but from what I have read, the OBD II Absolute Load data, which measures volumetric efficiency (air flow into the engine), is linearly correlated with brake torque. So using this, Engine RPM, and fuel consumption rate OBD II data, you could synthesize a chart very similar to a BSCF chart. Unfortunately, the different measurements are not synchronized. They are read at different times up to a second or more apart. A lot can change in one second. So it will take a lot of work to make the necessary corrections for this issue and you won't get a complete map since the engine will not operate in all regions during normal operation. You can see a plot of Absolute Load vs. Engine RPM for a 30 mile drive on highways for my FFE here: "http://www.fordfusionenergiforum.com/topic/1880-obd-ii-data-for-ice/?p=12267".

Edited March 16, 2014 by larryh

[Waldo]

The 140 F Generator Inverter temp seems to trigger a change in that cooling system loop because the temp never rises above 140 F even if I continue driving with the ICE on and the generator working to charge the HVB. It appears that when the temp hits 140 F, coolant begins flowing more quickly or coolant begins circulating through the radiator when prior to that it wasn't. When the Gen Inverter temp hits 140 F, the temps of both it and the Motor Inverter begin to quickly drop, even if I'm continuing to drive in a way that would normally make them heat up. Further evidence that grille covers don't adversely impact the hybrid components.

 

Is there a way to read the position of the active grill shutters? Are they being commanded open when you hit that 140F? It would be interesting to see just when they are open at all, my guess is their main reason to open would be to provide air to the A/C condenser more than anything else.

[acdii]

Seeing that leads me to believe the real issue I had with the first car was the fact it never warmed up in my daily driving, even with both grills covered up. The only time I saw it get low 40 was when the service manager had been driving it back and forth on 14 for 4 hours. I would drive all the way to work and had very little heat. Even with the covers when I was in city traffic the temps would drop to 125*. Even driving in Florida in 70* temps it couldn't get 40. I haven't measured the temps on the one I have now, but I can tell you it doesn't have that issue, I have heat, and good gas mileage. It was 16* this morning and I managed to get 40 MPG.

[hybridbear]

Is there a way to read the position of the active grill shutters? Are they being commanded open when you hit that 140F? It would be interesting to see just when they are open at all, my guess is their main reason to open would be to provide air to the A/C condenser more than anything else.

Not that anyone has found. That's an interesting theory on the temp dropping. I will have to look more closely at the data to see if coolant temp and intake temp are also affected at that same moment to indicate that the shutters are opening.

[Waldo]

Seeing that leads me to believe the real issue I had with the first car was the fact it never warmed up in my daily driving, even with both grills covered up. The only time I saw it get low 40 was when the service manager had been driving it back and forth on 14 for 4 hours. I would drive all the way to work and had very little heat. Even with the covers when I was in city traffic the temps would drop to 125*. Even driving in Florida in 70* temps it couldn't get 40. I haven't measured the temps on the one I have now, but I can tell you it doesn't have that issue, I have heat, and good gas mileage. It was 16* this morning and I managed to get 40 MPG.

 

You better practice a bit more. It was 12* over here and I got 43 this morning.

[acdii]

 

You better practice a bit more. It was 12* over here and I got 43 this morning.

I have hilly terrain, and 55MPH roads, so getting what I get is right about what I expect. If it were all driving in 45MPH roads and mostly flat like CC drives on, I can see those numbers too! :)

[corncobs]

I think its the mix between 35 - 55 MPH and 65 MPH on the Interstate that does it for me. The cold weather is not helping that's for sure last week @ 49.9 @ 40* today 43.5 @ 20*

[acdii]

Your biggest gain is from starting out slow, where right out of my driveway I am doing 55 MPH, and continue at that speed for a good 20 miles with stops and turns and acceleration back to 55. No real Hybrid roads until I get into CL, thats where I gain back some of the lost MPG. Terrain and speed have huge impacts on the cars.

[hybridbear]

Is there a way to read the position of the active grill shutters? Are they being commanded open when you hit that 140F? It would be interesting to see just when they are open at all, my guess is their main reason to open would be to provide air to the A/C condenser more than anything else.

The 140 F Generator Inverter temp seems to trigger a change in that cooling system loop because the temp never rises above 140 F even if I continue driving with the ICE on and the generator working to charge the HVB. It appears that when the temp hits 140 F, coolant begins flowing more quickly or coolant begins circulating through the radiator when prior to that it wasn't. When the Gen Inverter temp hits 140 F, the temps of both it and the Motor Inverter begin to quickly drop, even if I'm continuing to drive in a way that would normally make them heat up. Further evidence that grille covers don't adversely impact the hybrid components.

It appears that in one instance I found in my data of this happening that I was off in my guess.

 

Here's what the data shows for beginning data when the ICE came on:

time - 6:02:08 pm

coolant temp - 158.0

Gen Inverter Temp - 116.6

Motor Inverter Temp - 122.0

Useable SOC - 27.7%

 

The ICE came on and the car began charging the HVB with 30-37 amps flowing into the HVB. The Generator Torque was consistently around 27-28 newton-meters and the Generator RPM was between 3500 & 4500 RPM. The Gen Invtr Temp quickly rose from 116.6 to 140.0 in 21 seconds. By that point the useable SOC had climbed to 38.4%. At that point the rate of charging the HVB slowed to only about 23-27 amps. The Gen Torque dropped to 26.5-27.5 n-m and the Gen RPM dropped under 3000 RPM and continued dropping all the way down to 1500 RPM, all the while continuing to send the same amount of amps back to the HVB. ICE RPM was between 2100 and 2300 the entire time. As soon as the Gen RPM began to drop the Gen Invtr Temp began to drop. The Motor Invtr Temp also began to drop. This indicates that perhaps at that point the computer switched and began to send more of the output power from the ICE directly to the wheels. This allowed the ICE to continue charging the HVB at a slightly lower current flow, and explains the reduced Generator RPM and falling temperatures.

 

I don't expect there to be truth to the theory that the grille shutters opened when the Gen Invtr Temp hit 140 because Catalytic Converter temp and collant temps continued rising. The intake temperature didn't considerably change either.

 

Here are the peak temps for the hybrid components:

time - 6:02:33-6:02:37

Gen Inverter Temp - 141.8

Motor Inverter Temp - 125.6

 

Here are ending temps when the ICE turned back off:

time - 6:03:20 pm

coolant temp - 183.2

Gen Inverter Temp - 113.0

Motor Inverter Temp - 109.4

Useable SOC - 51.7%

 

This section of ICE runtime was unique in that the ending Gen Invtr Temp was lower than the temp when the ICE came on and the Generator added 24% useable SOC to the battery (Absolute SOC rose from 41.8% to 50.9% i.e. 0.1274 kWh was added to the battery). Typically when the ICE turns off the Gen Invtr Temp is much higher than it was when the ICE first turned on.

 

Further analysis is needed of Gen RPM and Torque in relation to amps flowing into the battery.

[tr7driver]

I was looking for the shutters under the hood of my car and didn't see them. How can I find them?

[lolder]

When the ICE is off, the generator is not doing much at all except freewheeling when the car is in motion hence the low inverter temperature. When the ICE is on, it's doing a lot of things. It starts the ICE, charges the HVB, sometimes even partially powers the motor but above all controls the ICE RPM in conjunction with the computer to yield the power you are requesting with your foot. When you call for 30 hp worth of power, the system will operate the ICE at the RPM on the solid line of the figure 3 fuel map to yield that power ( kilowatts ). Remember the throttle is open almost all the way all the time so that's not how the RPM is controlled. It's controlled by the torgue load of the drivetrain, controlled by the generator, and the fuel injection. When the SOC is low, the system will add some more power to charge the HVB. That's usually observed by just a little more RPM.

Edited March 19, 2014 by lolder