In message , J.J. writes
Its pretty much essential on my wife's Ford Ka which has a small engine and where the aircon saps a lot of that power.
In message , DervMan writes
Hmm. Are there any electrically (rather than mechanically) driven AC units in non-hybrid production cars?
Not sure. But it wouldn't make any difference as the AC needs to get it's power from somewhere. Doesn't much matter if it's directly fromt he engine or via the alternator, it's still coming from the engine.
Wouldn't make any difference - the power still has to come from somewhere. And with a 4 or so kW alternator, you'd be into a water cooled one.
How do they make them so that the engine revs don't make a big difference to the amount of power going into the AC?
The message from Rob contains these words:
Though if engine derived it has to come /right now/ but with electrical systems the power drain is buffered by the battery. There's a limit to the mechanical load an alternator can place on the system, so any excess consupmtion will be replaced later during an off cycle of the AC.
The message from Tony Houghton contains these words:
I imagine they have a blow-off valve in the compressor so that once the desired working pressure is reached any excess is vented back to the inlet which would reduce the load.
I know, I was thinking about the battery acting as a buffer during the short periods that full power is needed for acceleration.
It would be such a large load - roughly the equivalent of the starter - that you'd need a considerably larger battery if the alternator wouldn't cope on its own.
As I understand it, it would need one huge big battery.
Hybrid cars run the petrol engine when one is using the air conditioning, to drive the compressor...
The message from "Dave Plowman (News)" contains these words:
But only for the duration of the overtaking or wotnot. I'm sure there /are/ people who run their cars at full throttle for hours on end [1] but most drivers don't.
[1] Not Peter Macmillan, obviously.In message , "Dave Plowman (News)" writes
Just a thought. It's something being investigated (
I would imagine that an electrically driven system would be easier than a mechanically driven one to design as a component which could be shared across different models or manufacturers.
Well, the compressor cycles in and out at the moment, so apart from just overtaking an electric system to make sense would allow for that too - as well as working efficiently at idle.
However, when first switched on the AC compressor can run at full effort for quite some time, so if the alternator couldn't maintain this, you'd need a very large battery indeed.
Think you'll find that's why they're still purely mechanical - unlike things such as power steering that can benefit from a part time pump.
The compressors already are.
The message from "Dave Plowman (News)" contains these words:
You've not seen my wife steering then? She could make a pump run full time!
Soon as the automotive voltage standard is raised;
It will be 45 volts. then Delphi and Toyota both have electric compressors, and they will only draw approximately 7 amperes. With a 125 ampere alternator, I don't even see that affecting fuel usage at all.
The head lamps draw more than 30 amperes, and with the day time running lights drawing 20 amperes. I would say there will be an advantage to buying air conditioned vehicles in the future.
Refinish King
horsepower,
Air conditioning compressors:
function by volume, at a given RPM. They reach their peak capacity and can pump no more than their maximum design capacity.
Otherwise the system would be plagued with freeze ups, constant mildew problems and a host of hose explosions and many other pretty problems.
Refinish King
addresses.
Whack is what a certain ethnicity says when:
They think something is crazy.
What another ethnicity (Mine) says when they want someone killed!
LOL
Refinish King
PS It's great to be Italian, you can joke about Italians, and no one "Whacks" you!
Delphi and Toyota both have systems:
Both are said to consume less than 7 amperes, so the battery size might be increased a bit, and alternators are already in the 125 ampere range, so soon you will see 150 and 175 ampere alternators. The beauty of this is, the alternators work at as low as thirty amperes, when not fully loaded.
Refinish King
You're not thingking are you?
7 amp 45v compressor = 315w Headlamps (130w) currently draw 11A at 12V, they'll be 3A at 45V (or if HID about 1.5A) DRLs (2x55+4x5) draw 130w too, or less if proper DRLs (30w fronts).So aircon will use a lot more power than lights, and you lights figures are odd.
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