Electric A/C compressor
#11
Re: Electric A/C compressor
There are losses in the generator, losses in the charging circuitry, losses in charging the battery, losses getting the energy back out of the battery, etc. Driving an A/C directly will use less energy than driving a generator, to a battery, and a battery to an electric motor. More transitions, more loss. The question is how much of a loss and how significant that loss is vs. passenger comfort. If its only 0.2MPG you decide one way... if its 2-3 you decide another.
A Prius gets great gas mileage with an electric AC compressor, but that doesn't mean it couldn't have gotten even better with a normal one.
An expensive but nice solution would be a compressor that had a clutch to be driven by EITHER power source...whichever were available and a thermostat so the compressor isn't on all the time.
#13
Re: Electric A/C compressor
Running the ICE ONLY to recharge the battery back because the A/C exhausted it, is also a horrible waste of FUEL.
IMHO, the bottom line is there no magic that can yield free A/C.
IMHO, the bottom line is there no magic that can yield free A/C.
#14
Re: Electric A/C compressor
Well another thing to remember is that when its an electric A/C compressor it has less wear and tear in that it is not dependent on the engine turning it and very different speeds depending on the rpm. It runs as its needed and at peak efficiency. I had an 08 FEH and loved it but I too did not like having to idle at a stop light or in heavy traffic just to be cool on really hot days. I agree either way there is a "cost" to running the A/C, but I like that there is less wear and tear on the engine because it can shut down and still be cool when i'm in traffic or at a red light. I am not too worried about battary life and the cycles it goes thru, my friend has a 01 prius with 150,000 miles on it with original batteries and it runs like a champ. he still gets over 50mpg every tank!
#15
Re: Electric A/C compressor
I really believe that if there is a difference it is insignificant and the two mfg's chose different routes based on their goals/needs. Ford seemed to opt for wear on the engine and compressor as opposed to the battery, Toyota seemed to opt for passenger comfort and not worry about adding charge cycles to the battery. Ford may have chosen to play it safe, but with the 10yr warranty, the replacement cost of the battery, and the bad publicity that failing batteries would cause, I can't argue with it from their perspective. A domestic car company can't afford any worse of a reputation....or an increase in losses.
#16
Re: Electric A/C compressor
Why not also complain about the hybrid battery being used to act as a re-charging alternator (DC-to-DC down converter/inverter) for the 12 volt battery even when the ICE isn't running...??
The hybrid battery is the ONLY source for the 12 volt battery charge and what is the AMPERES consumed that way..??
Last edited by wwest; 05-31-2008 at 09:12 AM.
#17
Re: Electric A/C compressor
Another consideration is the strength of the A/C. My husband SERIOUSLY looked at the Prius when buying a new car 2 years ago but even with the A/C on full blast, as the back seat passenger during the test drive, I literally had sweat running down my back for the entire 15-20 minute ride because it was so hot back there. The A/C really didn't do anything for passengers in the rear. Granted, YMMV (we live in Central FL and the "extreme heat 8 months out of the year" situation might not be as much of an issue in other places) but we weren't going to own a car where we couldn't keep all riders, including those in the back, comfortable.
Granted, that was 2 years ago and perhaps things have changed with the Prius now, I don't know. But when deciding to buy a hybrid, "how well the A/C worked" was a very important question. And if cooling the car off means losing some MPG sometimes (once it's cool, I can switch back and forth between recirculating the air and cooling it again when it starts to get too warm), so be it.
Granted, that was 2 years ago and perhaps things have changed with the Prius now, I don't know. But when deciding to buy a hybrid, "how well the A/C worked" was a very important question. And if cooling the car off means losing some MPG sometimes (once it's cool, I can switch back and forth between recirculating the air and cooling it again when it starts to get too warm), so be it.
#18
Re: Electric A/C compressor
To get the best cooling efficiency and improved FE the way to run these new automatic climate control systems is to set them to use recirc mode ONLY, MAX cooling, lowest temperature setting, and then use the manual control of the blower speed to set your, and your passenger's comfort level.
#19
Re: Electric A/C compressor
One must also consider the cost of an electric compressor. The FEH uses of the shelf standard Ford compressor. The Prius and Camry Hybrid use a special compressor that is VERY expensive.
#20
Re: Electric A/C compressor
Amps? 300w / 14.4v = about 20 amps.
Our hybrid battery packs can put out high peak wattage for short periods of time.
Our hybrid battery packs cannot put out high wattage for extended periods. These are "D" size flashlight batteries.... Not deep cycle submarine batteries!