The Honda Civic Hybrid uses a Hybrid A/C. It can run off the electric when stopped at a light and can run off the ICE at other times.

It talks about it around the 7:50 point here:
http://world.honda.com/HDTV/news/200...05b/index.html

 

Does the ICE turn off when the compressor cycles off? ( there is a circuit to prevent the evaporator from freezing up, usually set to 29 psi on the low side to turn off compressor till the pressure rises to 45 lbs or so,) If so then a simple thermostat could be desiged to short cycle the A/C system to moderate the temperature instead of using the cooling/heater system. This would not affect the computer systems. Thus the ICE would run less and still maintain reasonable cooling.

 

If you are in stop and go conditions, and outside temperature is above 70'F, your A/C is going to come on for the battery pack after 10 minutes of driving, and need to sporadically cycle to chill the battery for the rest of your drive.

The A/C zone to the rear runs MUCH more than any of you are aware.
You're gonna have to hook up some meters like I did, or just trust me on this one. You really don't want to mess with the A/C system.

There is a "middle ground" where the battery is "warm" but not "hot" and A/C will activate only when the ICE is on for other reasons. EV works as usual. Beyond a point, the battery DEMANDS A/C no matter what, and EV is disabled.

This happens to me every day now that temps are above 70's.
I can be perfectly comfortable with a window down, but the battery, being in a confined space, is not. Especially, if you parked it outside all day, the battery may be "hot" before you even turn the key. The battery requests A/C when it is over 85'F I think. Now you think. How often is the inside of your car over 85'F when parked? Rolling down the windows cools the air in the cabin quick, but NOT inside the battery encloseure.

I revealed in another thread, that due to blower noise, the blower speed is at a minimum when you are at stop lights or traveling slow. Blower speed increases with vehicle speed, as road noise masks the blower speed.
Blower speed is never more than 40% when you are standing still or moving less than 15 MPH. I think it may be as low as 25%.

So, stop and go heats the battery.
Stop and go keeps the blower speed slow.
Stop and go requires A/C use after 10 minutes at 70'F.
Battery A/C is required above 85'F.
You often have your battery above 85'F before turning the key.

My recommendation: Don't mess with the A/C in this car!
-John

 

I don't think anyone is suggesting "messing" with the A/C, just looking for explanations/discussions as to why the Prius has an AC operated A/C and the Ford does not.

And why does the FEH/MMH hybrid battery need cooling, undersized/powered/over-stressed for the application, weight of the vehicle? What happens if the A/C or even the battery cooling fan should fail and the battery begin to overheat? No hybrid CVT drive means no drive at all.

 

Does the A/C come on even when turned off at the dashboard, if the battery needs it?

 

Yes the compressor will kick on. There are two separate cooling loops so the cooling loop that flows into the cabin system won't be activated (ie you won't get cold air out the vents until you turn on the A/C in the cabin) but the cooling loop to the battery will be active.

 

There is an isolation valve in the front system that does not allow freon to flow into the front evaporator unless the a/c is turned on. I have purchased the Ford factory shop manuals for the 2007 FEH/MMH. I do not recomend them to anyone who is NOT a highly trained emissions/automotive computer tech though as they are VERY technical and require a very good working knowledge of Ford computer systems. ( I am)

 

Oftentimes the way multiple cooling loops are engineered into one compressor system is by valving the refrigerant flow, outflow pressure limited, DOWNSTREAM of one or all of the individual cooling evaporators. That way neither cooling system will be allowed to HOG all of the refrigerant cooling capability.

Most F/R minivan systems, including the Aerostar use that method.

 

When the battery is charging, about 1/3 of the energy is wasted as heat given off by the battery pack. This heat must be carried away form the batteries, or the batteries will be destroyed.

 

1/3rd...??

I don't think it would be that high, maybe 10%

And a battery's internal resistance doesn't vary much for inflow, charging, versus outflow, discharging. Although you might be correct for a reason other than the battery itself. The charging periods, spikes, from brake use are sometimes high on energy but short in duration. If the energy available from those is to be captured ENTIRELY the battery much endure short periods of high current inflow, charging rates.

And the reference, comparison, is/was with the Prius, which does not have "direct" A/C cooling for the batteries.

So the question remains, why does the FEH/MMH require direct A/C cooling of the batteries?