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Discussion Starter #1 (Edited by Moderator)
Since the biggest thing holding electric cars back is battery technology, EV converters need to be careful in how they use the power they have. As a result many EV converters avoid having air-conditioning since the power draw has a noticeable effect on range, others decide the small sacrifice in range is worth it for the increase in comfort. Here are several options for keeping the occupants of your EV cool and comfortable:
  • No Air-Conditioning: Air-con uses the same amount of power in an ICE car or a EV it is just less obvious in a normal car. Once the drain of air-con is realised many people decide that having the window open or using the fan alone are sufficient enough cooling for them. If range is a big priority and the temperatures of your area don't get excessively hot then this is the simplest and best option.
  • Dual Shaft Motor: If having AC is a must for your conversion then the option that is most similar to AC in a normal car is to run the AC compressor off the rear shaft of a dual shaft motor. The advantages are simplicity and similarity to standard cars but the AC will only work when the motor is spinning. This Saab is an example of using this approach.
  • Accessory Motor: Another option is to run a small 12V accessory motor which is attached to the compressor. This approach allows AC to be used when the car is stationary and means that there is no direct drain on the power to the drive motor but adds weight and complexity. This Honda is an example of using this approach.
  • Ice: Rather than storing electricity and using it to lower the temperature of the car it may be easier and cheaper to store a direct source of cooling; ice. Blowing air through an ice water mix is a rather effective form of cooling and might be sufficient for your cooling requirements. A DIY example can be seen here, or you may prefer Mr Sharkey's no nonsense approach here.
  • Compressor with integral motor: A more recent option is a compressor with a motor built in like your home AC unit. Some of the newer hybrids use this technology such as the Prius or this conversion which utilizes a variable speed control to maximize efficiency. This is probaply the best solution, as this is also used by all of the OEM. With this option you also have more freedom as to where to locate the unit and you don't have a lot of mounting hardware to fabricate. http://www.evdrive.com/prototypes/category/e-car-e46/components/ac-motorcompressor/ Extension of the above is DC powered complete unit. Expensive , but compact. DC-Breeze is an example. ~$2,500 for 5,000 BTU / hr cooling all in a ~50 pound package... just plan for the ~580 Watt load to run it. Another integral motor option in 2011 is Cool Blue Air Conditioning Compressor/Condenser Unit, using your original evaporator. Another compressor you find at http://www.Sandten.de (only in German). This is a similar part used by OEM`s. And it is very competetive price.
  • Seat Heater-Cooler: Like some new vehicle seats cool the drivers backside. Thermoelectric cooling ( TEC ) technology. [Peltier] (From an advertizement) Inside the seat pad there is 6 polyethylene tube flask in the fire proof material. 1/3 of the tube can be felt when human body touches the surface. And immediately you can feel cool or warm. The car seat cushion’s power consumption is 30W. Working continually 33 hours will consume 1 watt–hour electricity. The thermoelectric ( TEC) car seat cushion works in low safe 12V voltage both it's cool and warm function. The tube, which carries antifreeze, can bear 150Kg pressure. And there is a pump inside the power box that transfers cool or warm to the pad surface. The power system is separated from the seat itself. In low voltage condition it is very safe to use in normal. All the materials are fire resistant to ensure safety. The circulatory system is airproof and no probability of leakage. Huimao China
A non-technical solution to either help reduce air conditioner usage, or eliminate it altogether, is to keep most of the radiant heat out of the vehicle cabin in the first place, whenever the vehicle must be parked outside. This is done with a reflective shield commonly known as a folding windshield sun shade.

For a custom fit, reflective mirror-finish plastic sheeting (a Mylar emergency blanket) can be cut in the shape of each window, and either attached to the inside of the windows using suction cups, or attached to the interior steel frame around the door using magnets.

This solution is a hassle, as the reflective shielding must be removed and stored whenever the vehicle needs to be used. But it will significantly reduce the cabin temperature when the vehicle is used, and the seats will not be frying hot.

A more elegant implementation would involve roll-up reflective window shades permanently installed on (or more complex yet, hidden within) the cabin ceiling above each window. But this is difficult to implement due to the curvy and irregular shape of door and window openings, and in newer vehicles, could damage hidden side-curtain airbag systems while trying to mount the roll-up shade to the cabin ceiling.
 

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I wonder about the suggestion to use a 12 volt motor for the A/C compressor. The vehicle linked to uses a 180 volt motor running from pack voltage. I don't know if a 12 volt motor would have enough power, or draw too many amps, plus you get conversion losses from the DC/DC converter.
 

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I'm pretty sure the only 'right' way to retain AC is to use a dual shaft motor (one with a shaft off both ends), and hook the pully up to that. Practically lossless, unlike DC converted from the pack!
 

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Well there has to be some loss from the belt running around the pulleys and clutch even when disengaged, though I'm not sure how much. Also the A/C stops when the vehicle stops unless you hold the throttle, and not all motors, (like mine) have dual shafts. I think a pack voltage motor might be a good solution.
 

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I suppose there would be some loss from spinning the clutch and pulley, I imagine it would be less loss than converting that many amps to 12v though.
The plus side would be the converter you can just switch off.

Personally I wouldn't be concerned about the pump not running at stop signs or whatever, whenever the car was in motion it would be spinning the electric motor through the drivetrain, powering the AC, and actually capturing a bit of power via 'regenerative braking via air conditioning' :)

A motor on pack voltage would be the 'correct' way too, provided it was sized correctly.

Anybody have any idea how we'd select the right rpm/power motor for the AC?
 

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Although not the strongest why not use circa 1920's technology?

Passive AC does work but would present an aerodynamic issue. (a big 2' tall 4'x4' dome) There is a place here in Wausau WI working on selling passive portable refridgerators for developing countries, I would assume this same technology would work on a car, insulate the roof, put on a big screen magnifier over a nice set of black AC lines. THe sun compresses the refridgerant and cools the other side.

I doubt it would be strong cool but it would gently cool the roof area.

Now lets see if I can find the joints name, at the moment they are still in the business incubator. Their initial designs were marketed toward large scale business AC, minimal energy needed to make the hi-tech version operate.

Cheers
Ryan
 

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When you drive an ice car with the ac on, and then turn off the motor, do you occasionally hear a sound from under you're dash or hood? That's the sound of the ac system equalizing pressure through the expansion valve. The high side, high pressure liquid is vaporizing in the evaporator and settling on the low side. the evap will usually be able too cool for a minute or so after the engine shuts off. On an e car, I would run the ac off the traction motor, install a larger receiver to hold a little more liquid freon and a larger accumulator for added low pressure space. When you're motor is off, at a traffick light, there should be enough to keep the ac going for a few minutes. You want someone to carfully calculate the charge, as this is a high pressure system and if you're accumulator is too small, you'll hammer the compressor with liquid, which destroys it. Remember, not only do you have to somehow power the ac compressor(seperate motor, traction motor, or motor compressor packaged unit) but you also have to run the electric fan that pulls air throught the condenser, these usually draw a lot of amps. Ac is a luxury and in arizona, it'll have to be a reality!
 

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http://www.myettnews.com/2009/05/battery-based-sunspot-5000-under-bunk-ac-offers-5000-btus-of-cooling-power/

Sun Power Technologies has launched the Sunspot 5000 in-cab, an under-bunk 12V-DC air conditioner that delivers 5,000 BTUs per hour of cooling capacity, its maker said. The self-contained system’s compact design is versatile enough for almost any under-bunk retrofit application and offers easy installation, according to the manufacturer. Weighing 67 lbs. installed, the system utilizes a hermetically sealed 12-V DC compressor and 12-V blowers and controls with complete circuit protection. It draws 50 amps.
 

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What about something a little simpler? Think absorption refrigeration. I know from experience that about 200 watts will get you quite a bit (?) of cooling power. The challenge would be getting existing cooling units to fit in a car- locating the coldplate in the existing cabin air system the biggest I can think of.... I do know theres a rebuilder in Oregon that might be able to modify an existing cooling unit to make it more installable in a car... could be a great savings of power if done right. Also check out the Einstein refrigeration loop. There a fellow at Oxford (http://www.guardian.co.uk/science/2008/sep/21/scienceofclimatechange.climatechange) who has revisted it and claims to be able to quadruple the output from the system from tweaks and going from the conventional water ammonia solution to a butane ammonia solution. Solar or waste heat could easily drive the system at that point! Anyway just a thought to ponder. Dennis
 

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thermo electrics are themselves less efficient directly.... but there are side issues... that might tip the scale in some cases.

Thermo-electric devices can be put in series up to the main pack voltage ... thus the only losses to get the energy to the thermo electric device is a high efficiency PWM to control current flow... or just scale it so you are happy with it at one power level then no PWM is needed.

A simple high efficiency PWM will easily be as efficient if not more efficient than the main EV motor controller.

running anything off the main drive motor would also include the efficiency losses of the motor itself + connecting belts and such.

So the Thermo Electric itself is less efficient ... but power can be supplied to it more efficiently than driving off the main motor ... or going through any type of electric motor driven compressor.

So TE system:
Main Pack = ~99% energy applied to much less efficient TE device for AC.

vs conventional AC compressor systems:
Main Pack - efficient Motor controller - efficient motor = less energy applied / less efficiently used energy .... to a more efficient itself AC system.

- - - - - - - - - - -

The other side of Thermo Electrics is

They are solid state devices with no moving parts.

They are themselves flat and relatively thin ... thus some creative packaging options become available ... the volume of a compressor is not needed.... just the a TE radiator / heat sink and a moving working fluid / gas.

TE can also run in reverse... not just to Heat instead of cool ... but to generate power instead of consume it.

One of the crazier Ideas I had once upon a time ... was to install the TE radiator on the roof of the cabin ... but under the shell so as to not mess up aerodynamics ... than when the car is parked and the sun heats up the cabin and the cabin's inside temperature gets hotter than the ambient outside temperature ... the TE system could produce some small amounts of energy conversion and turn some of that car heat into energy .... than when I want it... I can throw PWM main traction battery power to the TE system to get cool air... of course only on those days the inside gets 20+ deg hotter than ambient.

One more thing for a TE system ... they cost more $$$ than conventional AC compressor systems.
 

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cloud electric sells an ac system that can attach to your car's existing dash system for 450 bucks, all you need to do is get a 1000w inverter to operate it and power the inverter through the accessory pack. the fittings can be made at any local line shop. and it installs in the motor compartment.
 

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Well, noob, the only problem with that is the fact that amonia will kill you or cause brain damage, should the be any kind of leak.
They were used for a short while as ac units, but never really caught on.
 

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I suppose there would be some loss from spinning the clutch and pulley,
Why not stick the clutch at the CE shaft instead, so you're only driving a part of that pulley, if it's the only thing being driven by that belt anyway?

Save you a little energy when you are not using the AC, especially for extended periods like when it's winter, etc.
 

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dont know what you mean with amonia, they use freon, same as the car, and just as safe. its called cool blue, its made in flagstaff, here is the link
http://www.electricbluemotors.com/products.html,
Actually I don't think Freon, (R12), is allowed any longer, it's probably R134 or something. As for the electricblue products, they look like a total ripoff to me. Their heater is a $35 Katz block heater and a $45 pump, just like I have, and they want $375 for it, PLUS you have to buy a $500 inverter since they didn't convert it for DC! Their AC units also need this inverter, probably because they look like compressors from home AC units!
 

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you are absolutly right but the title of this thread is Air-Conditioning Options, I know that it is an ac and not a dc compressor. but you dont need to buy their inverter, the unit pulls 4 amps continous and about 10 on start up, so a 1200watt inverter would run it great, and can be bought for 120 bucks at inverters r us, now it will take a lot of power, but change the accessory battery to a deep cycle 120 amp hour and it will be good for a few hours. I do think that the other stuff can be gotten cheaper elswear, but people spend thousands on there conversions, with that in mind I think that is a great way to get ac in you ev for cheap and Im all about that. if there is something else I would love to hear about it, so that I can buy the one that is the cheapest for my ev. after all it is hot here in phoenix.
 
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