The current FEH has its own heating and cooling (air conditioning!) system. The software limits the hybrid battery SoC to normally range between 40-58%. It is possible to sometimes exceed the upper limit (downhill) but Ford put this limit in to preserve longetivity. There was a thought the 2008 FEH has a range of 35 to 65% hybrid battery SoC but this remains unconfirmed.

There is an individual in Indiana who has hacked the Prius software and piggybacked two hybrid battery packs for a PHEV.

2005 AWD Escape Hybrid
Best Interstate tank trip MPG 39.02 (scangauge II) for 402 miles on I-70, 10.3 gallons used over mostly flat terrain.

Best Interstate tank trip E30 MPG 34.6 for 271 miles along I-80 in Indiana and Ohio.

Best multiple road tank trip E30 MPG 36.2 for 202 miles in Southwestern Pa.

are you referring to Steve W? If so, I have already been in contact with him, technically the same thing COULD be done to the FEH (cooling issue would need dealt with), but space is more of an issue, unless you don't ever carry any cargo. That is one advantage the Prius has, they included a nice big space for an add on battery under the cargo floor!

Jeff Jones

2006 FWD FEH,
hopefully one day to be a PHEV (pet project)

The NiMH batteries have a 5 mv, dV drop that needs to be detected but that is per cell. In the Prius, we have six cells per module so that means detecting 30 mv drop for a voltage that will be around 8.5 VDC at the peak. That means your voltage sensor has to detect going from say 8.50 to 8.47. This means a quality voltage measurement system, at least 3.5 digits but 4 would be better.

Also, you want to stop the charging for each individual module or series of cells when _THEY_ show the 30 mv drop. This of course assumes the six cells within the battery module are fairly balanced and that is a bad assumption when the battery module has lost a significant amount of water from the electrolyte.

The temperature probe is the backup system and it is critical in case the cells become unbalanced. The failing cell will increase the temperature and this higher rate than normal charging means _STOP_!

I'm not trying to be an alarmist but emphasize the importance of a good design that is as solid as possible. A weak design with significant noise would be unreliable and might result in "bad things."

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

Just for information, this is the hybrid battery case opened.

2005 AWD Escape Hybrid
Best Interstate tank trip MPG 39.02 (scangauge II) for 402 miles on I-70, 10.3 gallons used over mostly flat terrain.

Best Interstate tank trip E30 MPG 34.6 for 271 miles along I-80 in Indiana and Ohio.

Best multiple road tank trip E30 MPG 36.2 for 202 miles in Southwestern Pa.

Steve Woodruff is the individual. He is located 75 miles south of Indianapolis along the interstate highway.

2005 AWD Escape Hybrid
Best Interstate tank trip MPG 39.02 (scangauge II) for 402 miles on I-70, 10.3 gallons used over mostly flat terrain.

Best Interstate tank trip E30 MPG 34.6 for 271 miles along I-80 in Indiana and Ohio.

Best multiple road tank trip E30 MPG 36.2 for 202 miles in Southwestern Pa.

I don't think we can say for sure that Ford's PHEV is charged to 100% of capacity.
It is being charged to 100% of what Ford considers "safe". You never drain the battery all the way down either.

And yes, you can get battery boost at any speed. Not having faster EV is not a big deal.
-John

According to presentation slides from Phil Rairigh @ Ford, even in a non-plugin hybrid, the Traction electric motor provides a good portion of the power at all speeds, just as speeds are higher, more of this electricity is coming from the generator (& ICE), less from the battery. So it makes sense that a larger battery could provide more of this electricity requiring less from the ICE thus improving your mpg, as long as the charge is not being replenished by the ICE and GEN, but instead by an outside source such as a plug in charger.

Jeff Jones

2006 FWD FEH,
hopefully one day to be a PHEV (pet project)