Am I missing something? All the info I have seen shows the Escape has a larger capacity pack than either the Prius or Highlander....

The Prius currently uses a 168 Cell, 201.6V battery pack. Even the older Prius only used a 240 Cell, 288V battery pack. The current Highlander also uses a 288V battery pack, presumably consisting of 240 cells. The Escape/Mariner Hybrid uses a 250 Cell, 330V pack.

 

Number of cells is meaningless absent the AH rating of each cell, more cells simply means higher voltage assuming standard series connection.

I too had assumed that the FEH/MMH had a heavier duty hybrid battery configuration, as is clearly justified. On the other hand if it is a lower AH capacity then than explains something that has puzzled me.

A lower (basically under-capacity) AH battery rating would justify the need for A/C cooling.

 

"..fixed speed compressor running off the high voltage..."

No engineer worth his salt would consider a constant speed compressor using electric power derived from a high voltage source as is the hybrid battery.

The correct way to go would be a variable frequency AC drive so that the compressor can be driven at whatever speed is necessay for quick cool-down and then just idle along thereafter.

Even many modern day ICE driven compressors are now variable displacement for the same reason, more efficiency, FE, plus being able to "hold" a constant pumping rate independent of ICE speed.

Patented...I don't think so.

Solid state DC-to-AC inverters, even variable frequency AC-DC-AC ones, are now far to common, even going all the way back to the late sixties, for that to get by the patent office.

 

The TCH's A/C compressor is indeed a variable-speed, 3-phase, ac unit driven by an inverter from the high-voltage (245-V) NiMH battery. The attached pages (especially from page BE-51 on) from the New Car Features Guide give the relevant details.

Stan

 

Indeed. In any case the point is that by decoupling the compressor speed from engine RPM you can optimize the HVAC system for efficient performance instead of worrying about the wide range of speeds the ICE operates under. It seems to me this would allow use of a smaller compressor since you don't need to size a unit large enough to provide adequate cooling at engine idle.

 

FYI, here's some specific NiMH battery information for the TCH:

• 204 cells @ 1.2 V each = 244.8 V nominal
• Each cell is 6.5 Ah capacity, giving total energy storage of 1.6 kWh = 5.7 MJ

Stan

 

The Ford Escape Hybrid has:

250 cells
330v nominal voltage
Which would mean 1.3v per cell ( never figured out why this is different )
6Ah or 5.5Ah depending on who you ask...

So the FEH battery has between 1.98 kwh and 1.815 kwh.

 

Toyota uses a trapezoidal cell instead of the conventional round cell used by Ford, which is supposed to be higher in capacity and density. I don't remember all the details. I do know that battery packs for different models have different capacities. I believe the Prius has the largest capacity compared with Highlander or Camry, but probably shouldn't quote me on that.

 

The ampere-hour value is 6.5 Ah on Toyota and 5.5 Ah on Ford.
http://www.eaa-phev.org/wiki/Escape_PHEV_TechInfo
http://www.peve.jp/e/hevkinzoku.html
Prius uses the "Plastic Case Prismatic Module" and Highlander/Camry uses later designed "Metal Case Prismatic Module".
The ampere-hour values are same, 6.5 Ah.
The power-ratings are same, 1350W/7.2V=1800W/9.6V=187.5A
The cooling is better on the metal case.

If we say the capacity using total Wh value...
Prius: 201.6V X 6.5Ah = 1310.4 Wh
Camry: 244.8V X 6.5 Ah = 1591.2 Wh
Highlander: 288V X 6.5 Ah = 1872 Wh
Escape: 300V X 5.5 Ah = 1650 Wh (using same NiMH nominal 1.2V)

Ken@Japan

 

First, if it were not already necessary to keep the ICE running in order to have a hot water suppy to modulate, moderate, via the reheat/remix cycle, the CHILLING of the A/C system airflow, AND keep the catalyst up to the 800F operating temperature, all that would likely be true.

As it now is it is much better to use a direct drive variable displacement A/C compresssor.