Tell me about the C-Max HV battery and hybrid electrical system

[SPL Tech]

I just traded my Prius for a 2012 C-Max SL and I am interested in knowing how the hybrid components differ from the Prius.

1. What is the voltage of the HV battery, and is it called the HV battery as Toyota calls their 208V battery the HV battery?

2. Is there a step-up converter for the C-Max? Prius uses 208v battery to 560v converter.

3. Is the 12v battery charged by a power inverter like it is in the Prius? Prius uses a 1000W inverter. How many watts is the C-Max's?

4. What is the aimed state of charge for the HV battery? I think Prius aims to keep the battery about 30 - 60% charged during use.

5. Is the HV battery externally vented and internally cooled? Prius has an external vent to vent gases during charging, and it uses a blower motor to keep the battery cool.

6. Is the AC compressor electric and ran by the HV battery like it is in the Prius, making for a completely beltless ICE motor?

 

6.5: On the Prius, if you let your foot off the gas but dont touch the brake, while traveling at speed, the vehicle will apply a slight charge to the HV battery. Does the C-Max do the same?

 

7. In what other major ways does the C-Max hybrid system differ from the Prius' other than the C-Max can run EV at a much higher speed?

 

Thanks!

Edited November 18, 2014 by SPL Tech

[plus 3 golfer]

Welcome aboard.  Here's brief answers to your questions.

 

1. What is the voltage of the HV battery, and is it called the HV battery as Toyota calls their 208V battery the HV battery?
About 300 VDC
2. Is there a step-up converter for the C-Max? Prius uses 208v battery to 560v converter.
NO
3. Is the 12v battery charged by a power inverter like it is in the Prius? Prius uses a 1000W inverter. How many watts is the C-Max's?
Yes, there is a DC/DC converter with a capacity of about 145 A  or around 2000 W (14 V * 145 A)

4. What is the aimed state of charge for the HV battery? I think Prius aims to keep the battery about 30 - 60% charged during use.
About 30 - 70% SOC is the apparent working range but in typical driving the range is around 40 - upper 50%.  70% SOC can be reached going down a longer,steeper grade or from higher speed stops when the HVB is in the upper 50s. I haven't seen a SOC below around 35% when I monitor SOC.
5. Is the HV battery externally vented and internally cooled? Prius has an external vent to vent gases during charging, and it uses a blower motor to keep the battery cool.
The parts diagram shows a vent for the Energi but I don't see one for the Hybrid.   Both have blowers and are air cooled.
6. Is the AC compressor electric and ran by the HV battery like it is in the Prius, making for a completely beltless ICE motor?

Yes

6.5: On the Prius, if you let your foot off the gas but dont touch the brake, while traveling at speed, the vehicle will apply a slight charge to the HV battery. Does the C-Max do the same?

Yes, this is regenerative braking by the traction motor to simulate engine braking.

7. In what other major ways does the C-Max hybrid system differ from the Prius' other than the C-Max can run EV at a much higher speed?

Don't care to know details about the Prius. ;)  :)

[kostby]

There is no US-built model year 2012 Ford C-MAX Hybrid SL.

All US-built C-MAX Hybrids assembled during 2012 were tagged as 2013 models.

US-built C-MAX Hybrids are available in SE and SEL trim. All C-MAX Hybrid + plug-in Energi models are SEL trim.

 

7. Prius high-voltage battery is Nickel Metal Hydride (NiMH). C-MAX high voltage battery is Lithium Ion (Li-Ion).

http://auto.howstuffworks.com/lithium-ion-batteries-improve-hybrids1.htm

[Jus-A-CMax]

Welcome to the CMax family SPL Tech. Enjoy the quality refinements and as a former hybrid owner, my expectation would be to see you in the 600+ Miles CMax Club soon  ;)

Edited November 18, 2014 by Jus-A-CMax

[SPL Tech]

Sorry, I meant 2013 C-Max. On the dash, when the display shows a full battery, is that 100% SOC? And if it's fully discharged on the display, is that 0% SOC? Or is it 30 and 70%?

[stevedebi]

Sorry, I meant 2013 C-Max. On the dash, when the display shows a full battery, is that 100% SOC? And if it's fully discharged on the display, is that 0% SOC? Or is it 30 and 70%?

What you see is the percentage of usable battery, which varies under normal use between around 33% to 66%. It is not the actual maximum percentage of the battery capacity.

Edited November 18, 2014 by stevedebi

[MichaelM]

I believe you can see the actual percentage of charge in the engineering test mode.

[plus 3 golfer]

Sorry, I meant 2013 C-Max. On the dash, when the display shows a full battery, is that 100% SOC? And if it's fully discharged on the display, is that 0% SOC? Or is it 30 and 70%?

I've seen just under 70% SOC on my DashCommand App and the battery looks filled (including the tip).  Here's what HannahWCU observed.  For reference, his numbers are below.  SoC corresponds to displayed Battery Symbol number and SOC corresponds to actual HBV.  

 

When SoC reads 100 - SOC reads 69.7

When SoC reads 80 - SOC reads 62.1

When SoC reads 70 - SOC reads 58.0

When SoC reads 50 - SOC reads 50.4

When SoC reads 30 - SOC reads 42.7

[plus 3 golfer]

I believe you can see the actual percentage of charge in the engineering test mode.

Unless Ford changed ETM after certain build dates, I don't see it or recognize anything resembling SOC as a %.  Most displayed data has units associated with it.  Maybe there are additional screens that require additional input to view.

[MichaelM]

Unless Ford changed ETM after certain build dates, I don't see it or recognize anything resembling SOC as a %.  Most displayed data has units associated with it.  Maybe there are additional screens that require additional input to view.

Thanks Plus 3, I stand corrected. I was sure it was there but I've only been in the mode a couple of times, to see what was there. I'm unaware if there is a deeper view. I've been fortunate enough (knock on wood) to not have a real need to try to use any of that info for troubleshooting (57,000 mi. and counting).

Edited November 18, 2014 by MichaelM

[SPL Tech]

I noticed that when the car is in the ready mode but the ICE is not running, there is a down arrow on the HV indicator. So what is using the HV battery if the vehicle is not moving? Does the 300V HV to 12V LV converter run 24/7 when in the ready mode, and that's what is draining the HV battery?

[SPL Tech]

"The parts diagram shows a vent for the Energi but I don't see one for the Hybrid.   Both have blowers and are air cooled."

That's strange. If both models use lithom ion batterys, it would stand to reason both produce hydrogen gas that needs to be vented. I assume the 12V battery has a vent that extends under the car?
 

[plus 3 golfer]

I noticed that when the car is in the ready mode but the ICE is not running, there is a down arrow on the HV indicator. So what is using the HV battery if the vehicle is not moving? Does the 300V HV to 12V LV converter run 24/7 when in the ready mode, and that's what is draining the HV battery?

Yes, even in accessory mode the converter provides power to the 12V system albeit at a lower voltage than in ready mode. IIRC, it's 13 V in ACC mode and 14+ in ready mode.

[jdbob]

"The parts diagram shows a vent for the Energi but I don't see one for the Hybrid.   Both have blowers and are air cooled."

 

That's strange. If both models use lithom ion batterys, it would stand to reason both produce hydrogen gas that needs to be vented. I assume the 12V battery has a vent that extends under the car?

 

 

Lithium Ion batteries don't vent hydrogen - you are thinking of standard lead-acid batteries. There doesn't appear to be any vent for the 12V battery, it's so small that the amount of gas released is probably insignificant.

 

The extra vent for the Energi is most likely the external air intake vent while it is plugged in and charging - something the hybrid doesn't do.

[stevedebi]

"The parts diagram shows a vent for the Energi but I don't see one for the Hybrid.   Both have blowers and are air cooled."

 

That's strange. If both models use lithom ion batterys, it would stand to reason both produce hydrogen gas that needs to be vented. I assume the 12V battery has a vent that extends under the car?

 

As jdbob noted, it is for cooling the battery when the energi is plugged into the external plug. I'm not entirely sure where the vent is, but it is to the outside, and it is probably directly down.

 

When I plug in my Energi, I can hear the fan running back there.

[stevedebi]

I noticed that when the car is in the ready mode but the ICE is not running, there is a down arrow on the HV indicator. So what is using the HV battery if the vehicle is not moving? Does the 300V HV to 12V LV converter run 24/7 when in the ready mode, and that's what is draining the HV battery?

The car electronics are drawing some power. It doesn't take much energy to run the displays and power up the system, but any drain is still a negative pull on the battery. Hence the "V" indicator on the battery.

[SPL Tech]

Couple of other questions.

The prius hybrid has three main components, the ICE, the electric motor, and a generator. Does the CMAX have the same three componenets, or does the electric motor also double as the generator?

Also, I notice that the battery charges while costing even if the ICE is off. Wouldent it be more efficient to completely disengage the drive line from the engine to minimise drag and maximise crusing distance? Spinning the generator while cruising seems like it will waste energy because although it will charge the battery, it also puts drag on the drivetrain which is not wanted as the brake peddel is not being pressed.

Last, is the hybrid system completely DC? I read somewhere the motor is actually AC.

Any ideas as to the efficiency of the motor and generator? With energy being converted from gas to mechanical via the ICE, and then back to electricity through the generator, and then to chemical storage in the battery, and then back to electrical energy again via the electric motor, and then back through the transmission again, it seems like the energy losses would be completely astronomical.

Edited November 20, 2014 by SPL Tech

[jdbob]

The C-Max has the same three components in generally the same configuration.

 

The transmission doesn't have any clutches in it to disengage power sources so there are some losses. On the good side it makes it simpler. Coasting is a software simulation of a normal automatic transmission. If you put the shifter into "L" then the only the software changes resulting in more regenerative braking when you let off the pedal.

 

The two motors are permanent magnet AC Synchronous motors, see http://en.wikipedia.org/wiki/Synchronous_motor

 

So the power electronics under the hood (with their own liquid cooling system) have the job of converting the DC from the battery into variable frequency 3-phase AC for the motors as well as converting the AC from the motors (when used as generators) back into DC for the battery. In the Hybrid they have to handle about 35000 watts, in the Energi about 68000 watts.

 

For all the gory details about efficiency look for posts by LarryH in the Fusion Energi (http://www.fordfusionenergiforum.com/index.php) and to a lessor extent, in the C-Max Energi (http://fordcmaxenergiforum.com/index.php) forums.

[SPL Tech]

The C-Max has the same three components in generally the same configuration.

 

The transmission doesn't have any clutches in it to disengage power sources so there are some losses. On the good side it makes it simpler. Coasting is a software simulation of a normal automatic transmission. If you put the shifter into "L" then the only the software changes resulting in more regenerative braking when you let off the pedal.

 

The two motors are permanent magnet AC Synchronous motors, see http://en.wikipedia.org/wiki/Synchronous_motor

 

So the power electronics under the hood (with their own liquid cooling system) have the job of converting the DC from the battery into variable frequency 3-phase AC for the motors as well as converting the AC from the motors (when used as generators) back into DC for the battery. In the Hybrid they have to handle about 35000 watts, in the Energi about 68000 watts.

 

For all the gory details about efficiency look for posts by LarryH in the Fusion Energi (http://www.fordfusionenergiforum.com/index.php) and to a lessor extent, in the C-Max Energi (http://fordcmaxenergiforum.com/index.php) forums.

 

So the DC/AC converter under the hood converts the 300VDC, to what, 300VAC? Or does it step up the voltage? Is the 2000w power inverter located under the hood in the silver box with the coolent as well? 2000W seems a bit heavy for that car. That's basically 166A, which is larger than the alternator on most cars. A car the size of the CMAX would normally have around a 120A alternator. Any idea why the inverter is so large? The AC pump runs on 300VDC, right, so it doesent need the inverter?

 

I am curious why Ford dident go with a more efficient AC compressor. I see it draws around 1800W during first use, then drops to about 800W after a few minutes. Well, there are 12VDC freezers out there with compressors probably as large as the one in the Ford that draw less than 150W. The link below is for an 85 quart freezer that draws less than 12A at 12VDC. The compressors are supper efficient can can cool to -10F. Why dident Ford go with one of these instead?

 

http://www.amazon.com/gp/product/B002W8BLUG/ref=pd_lpo_sbs_dp_ss_3?pf_rd_p=1944579862&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B00I0GGNFC&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1M88VH3CM623MCD2HGK9

Edited November 20, 2014 by SPL Tech

[plus 3 golfer]

So the DC/AC converter under the hood converts the 300VDC, to what, 300VAC? Or does it step up the voltage? Is the 2000w power inverter located under the hood in the silver box with the coolent as well? 2000W seems a bit heavy for that car. That's basically 166A, which is larger than the alternator on most cars. A car the size of the CMAX would normally have around a 120A alternator. Any idea why the inverter is so large? The AC pump runs on 300VDC, right, so it doesent need the inverter?

 

I am curious why Ford dident go with a more efficient AC compressor. I see it draws around 1800W during first use, then drops to about 800W after a few minutes. Well, there are 12VDC freezers out there with compressors probably as large as the one in the Ford that draw less than 150W. The link below is for an 85 quart freezer that draws less than 12A at 12VDC. The compressors are supper efficient can can cool to -10F. Why dident Ford go with one of these instead?

 

http://www.amazon.com/gp/product/B002W8BLUG/ref=pd_lpo_sbs_dp_ss_3?pf_rd_p=1944579862&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B00I0GGNFC&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1M88VH3CM623MCD2HGK9

I think you are confusing the DC/DC converter with the AC/DC inverter.  These are two separate units.  The inverter is under the hood and liquid cooled.  The converter is in the HVB area and air cooled.  The DC/DC converter provides a max of 145 A (not 166 A).  IMO, this is not over sized given that it supplies power to a lot of hybrid control components in addition to the normal 12 V loads of a non-hybrid car.  The 2000 W is based on about 14 V converter output and 145 A.

 

The generator (MG1) and the traction motor (MG2) are controlled by the power electronics under the hood ( Secondary On Board Diagnostic Module / Transmission Control Module commonly called the AC/DC inverter).  AFAIK, as operating requirements change, the power electronics can vary the phases, frequency and voltage to MG1 and MG2 such that MG1 and MG2 can run as a motor or generator, at various speeds, and so forth.  I can guess at the ranges of the power control operation but it's not material.  

 

How do you know that the Ford AC compressor is not as efficient as the little frig ones????  The operating requirements of the C-Max AC electric compressor is not quite the same as the freezer compressor.  Evidently, you haven't seen the compressor output when it starts up in 110 F ambient temp, sunny, and cabin temps likely 130+ F.  I would think most consumers want the car cooled in minutes (not hours).  That little freezer compressor would likely never cool the cabin to a comfortable level in hours of driving.  I typically see just under 5 kW of AC load upon start up under the above conditions .  Once the cabin temp begins to drop, the AC load begins to drop and when the cabin temp set point is reached, the load is around 500 W +- a few hundred Watts depending on conditions.   At ambient temps in the 80s F and sunny, the AC load drops to around 250-350 W.   So, 150 W freezer compressor won't be able to keep up with the heat gain into the cabin even at ambient temps in the 80s F.