AC compressor tech questions

[The Bogan]

Remove ac condenser, replace with 42 volt alternator from ebay, anywhere from $300-$2500

Test and adjust 

My vote is high rpm reliability test of stock condenser 

What is the worse that could happen?????

[GTSBoy]

I've had this type of conversation lately with a couple of peeps on here.

The electric compressor is a good idea to prevent the on-off clutch problem from the compressor potentially cycling while at high revs. Granted, in the usage model of charge cooling, it would likely be stuck in the ON condition. But in the OP's usage case, it could quite likely cycle on-off when just working as an AC, even though he might be pooping out 7k rpm at the time. So, yes to elec comp on that basis.

But perhaps the better aspect of an elec comp is that you really need a 42V battery there for the alternator to run against. Now, ignoring the weight penalty of having to have another 18 cells of lead acid battery on board (in addition to the native 12V battery) (or potentially something like a lithium battery) you could then actually not even load the alternator while trying to extract max power from the engine. You'd use a clever charge controller between the 42V alt and the 42V battery that would allow charging on overrun and partial throttle, but reduce alternator current draw when above X% throttle opening, or some more sophisticated arrangement, if desired. Then you can still get the comp to run to produce the cools when you need it to cool your weary body (or the air charge) by leaning on the battery for part of the lap.

And so on, and so forth. There's a dozen things that you could come up with like that if you really wanted it.

[Chopstick Tuner]

On 31/05/2022 at 3:21 PM, GTSBoy said:

 

 

And....no. You're not going to draw 3ish kW of power from a 12V supply.

BEVs and hybrids that use electric AC compressors are running them on the 42V standard that sort became the thing when such high power demand applications started to become a thing, or even higher voltages. This because..... they have higher voltage available.

You wanna rig up a special alternator capable of putting out 42V, then yeah, maybe.

True, didn't think of the voltage they run at if using one direct from an EV. And the cost. 

Not sure what the aftermarket is like for stuff like that, obviously electric water pumps and ps pumps are popular, but they have a demand among track and motorsport cars hence the options exist. AC pumps however, not so much

[GTSBoy]

On 5/31/2022 at 2:03 PM, Chopstick Tuner said:

obviously electric water pumps and ps pumps are popular, but they have a demand among track and motorsport cars hence the options exist

And they only draw 1 to 2 digits of Amps. AC compressors would draw 3 digits (at 12V).