# Electric Air conditioning(In case you havent seen it)



## mizlplix (May 1, 2011)

SHM has a really nice set up for Hotrods that can work on an EV as well.

https://www.seanhylandmotorsport.com/SHM-electric-air-conditioning-compressor-3753

Ya, $1,200 is not all that bad except then you will need an Evaporator and condenser, but most cars have those.

Miz


----------



## palmer_md (Jul 22, 2011)

looks like a rebranded Masterflux.

http://www.masterflux.com/products/sierra/


----------



## Baratong (Nov 29, 2012)

I'm just about ready to pull the trigger on this:

Electric compressor: http://store.evtv.me/proddetail.php?prod=Benling

And everything else from: http://nostalgicac.com/complete-ac-kits.html


----------



## mizlplix (May 1, 2011)

Or you could do what Ivan did. He bought a 120VAC compressor for a small 1 ton window type unit and an inverter to run from a hefty pack of SLA batteries. It is supposed to be able to run 1 hour, which is just about what his traction pack should.

The compressor was around $350 if my memory is still working. 

Miz


----------



## PStechPaul (May 1, 2012)

Has anyone made a solid state Peltier module air conditioner? I recently bought a Black&Decker refrigerator for just $12 and replaced a bad Peltier cell with one I got on eBay for $6, and it's a decent 1.8 cubic foot fridge that runs on 12VDC and 10 amps (120W).




























Here are some plans:

http://www.instructables.com/id/Thermoelectric-Peltier-Air-Conditioner/

You can get complete 72 watt modules, including heat sinks and fans, for $17 each, so a 650 watt air conditioner would be about $150. These modules are not as efficient as a modern A/C, but 650 watts will probably provide about 3000 BTU/hour. And I think a solid state unit would be, well, _cool!_


----------



## samwichse (Jan 28, 2012)

Sadly they are only about 1/5 the efficiency of a standard A/C type.

Maybe it could be more efficient if you did something like a peltier-chilled coolant loop directly under the seat fabric where you didn't have to try to refrigerate a glass box in the sun?


----------



## PStechPaul (May 1, 2012)

I found a site that shows Peltier cells achieve about 5-8% of the theoretical maximum Carnot cycle, while conventional refrigeration is about 45%. However, they are promoting a new technology called "Cool Chips" with projected 55%. 

http://www.coolchips.gi/technology/ccalc.shtml

The Wiki reports 10-15% of Carnot maximum for Peltier coolers, compared to 40-60% for Rankine engines, so the figures may be a little better than first assumed.

https://en.wikipedia.org/wiki/Thermoelectric_cooling

It just seems like the fridge provides pretty good cooling for only 120 watts, but that is only 1.9 cubic feet compared to probably 20-40 times that for a car. ( [edit] A typical car has 100 cubic feet cabin volume.) And the greater amount of insulation and sealing, plus the lack of glass, combine to require at least 40 times the cooling. So with 5 times the COP with a pumped system, it would need 8 times the power, or about 1000 watts, which is about right for a small window A/C.

Maybe tinted windows could reduce the solar heating, and the effective volume may not be as much as I estimated because much of it in a car is taken up by the driver, passengers, seats, and other items. And perhaps a small solid state cooler could be used to direct cool, dry air onto the face where it is most needed.


----------



## PhantomPholly (Aug 20, 2008)

samwichse said:


> Sadly they are only about 1/5 the efficiency of a standard A/C type.
> 
> Maybe it could be more efficient if you did something like a peltier-chilled coolant loop directly under the seat fabric where you didn't have to try to refrigerate a glass box in the sun?


Same problem - any gains come at 5x energy expenditure of a simple compressor. If you need more cooling, just get a slightly bigger compressor. Also, the hybrid solution would require two separate air exchange systems to remove the heat, else the mixing may reduce the efficiency of the compressor. Complexity is always your enemy.

Scroll compressors are the best / latest design for AC. The one with the video showed an eccentric cam style compressor which is not bad, and I assume at that size and in a closed system the problems Wankel engines had with side seals is not as much of an issue as it was historically and would probably last for many years. 

I like the 12v model that accepts a range of voltages; it would also be useful for an airplane (and at 24v would only draw 15 amps instead of 30). Never knew they made those, or might have added AC to my plane. For EVs I think the one mizlplix posted is probably simpler, would use smaller wires for current allowing more flexibility in placement etc.


----------



## subcooledheatpump (Mar 5, 2012)

I'd be interested in hearing from anyone who has used the SHM, or the masterflux compressor. Seems to me they wouldn't be able to cool very well, especially in an automotive application. The SHM brand compressor features a maximum rated input of 900 watts. COP would have to be about 5 (which is unlikely) to get a reasonable amount of cooling power. The Benling compressor (link posted by Baratong), if the ratings are actually what they claim to be, would be better suited for an automotive application. The SHM/Masterflux appears to be a rotary compressor, which to be honest aren't very good. The Benling claims to be an orbital scroll compressor, much better choice.


----------



## AntronX (Feb 23, 2009)

subcooledheatpump said:


> The SHM/Masterflux appears to be a rotary compressor, which to be honest aren't very good. The Benling claims to be an orbital scroll compressor, much better choice.


Could you explain why rotary compressor not as good as scroll? Less efficient?


----------



## dragonsgate (May 19, 2012)

I would like very much to have air conditioning but don't really have room or want the extra weight. Money could also be a small factor. My daily drive is not that long time wise or far mile wise so I use a frozen 12oz water bottle. I wrap it in a thin tea towel and place it behind my head between my neck and the headrest when I drive. 90f + degrees out side and I have gotten the beginnings of a brain freeze. Say what you will but it is the best I can do for now. After all these years this will be the first winter with a real heater.


----------



## subcooledheatpump (Mar 5, 2012)

Scroll compressors tend to be more efficient than rotary compressors, as long as the pressure ratio ( difference between discharge and return pressures) isn't too high. They also tend to be more reliable, and they are usually gas cooled ( by the refrigerant ). Rotary compressors have more moving parts, and since they are usually not gas cooled, they tend to get quite hot


----------



## AntronX (Feb 23, 2009)

Thanks. I got bunch of Masterflux compressors for a bargain on ebay. Here is cutaway video of one I have. Looks like they cool it using high pressure gas. Why not cool it with cold low pressure gas instead? Looks like oil level would be critical, to keep that piece of sliding metal lubricated. I agree, seems like not a great design.


----------



## dcb (Dec 5, 2009)

it would be interesting, academically, to see a two phase inverter running a single phase motor with the caps and centrifugal switch bypassed, to see if it can be made more efficient off of a DC source. the small 120v ac units are a dime a dozen, and the sealed motors last a long time.

http://powerelectronics.com/power-m...it-phase-induction-motor-three-phase-inverter


----------



## dcb (Dec 5, 2009)

this is what the inverter waveforms would look like in relation to ground (reverse engineered from AC sources). a 240v plus pack could drive a 120v induction motor directly at 60hz without dc converters (or capacitors or centrifugal switches).

Of course if your pack is ~170v, you *could* just make a single phase 120vrms signal too with a full bridge.
edit, it is conceivable with a 144v pack to run the motor @50hz (might tweak the run cap).
edit2, a 5mfd run cap @ 60hz has like 500ohms, so likely the start coil doesn't need 120vrms direct, so likely the pack doesn't need a full 240v to run the motor directly off an inverter block. Somewhere between 170 and 240 for 60hz, don't know where.


----------



## skeyes (Dec 3, 2016)

Baratong said:


> I'm just about ready to pull the trigger on this:
> 
> Electric compressor: http://store.evtv.me/proddetail.php?prod=Benling
> 
> And everything else from: http://nostalgicac.com/complete-ac-kits.html


@Baratong,

Did you end up getting one of these Benling compressors? How did it go?

Looks like it could be a good option. Does it need a controller?

Thanks


----------

