I've posted this on a couple of other Suzuki Forums, but thought I might as well get as many opinions as possible..

My "86 tintop Samurai has never had AC, but as as I'm getting to be pretty old, I don't take the heat like I used to, and would like AC... I hear about the lack-luster cooling and power robbing the original AC provided.. I was just wondering how a modern electric AC compressor would work in a Sammy... I know you would have to install a larger alternator, and maybe even a second battery... I know the alternator would load up the tiny 1.3L motor, but would it be as bad as the mechanical compressor?... I'm thinking it would be using juice from the battery as well as the alternator... I have no idea about how many BTUs are required to cool down a Samurai, or how much the original AC had put out... Would this be a feasible option?...
Butch

I have wondered for some time when electric compressors would reach the automotive market.  I for one have been intrigued by the idea for quite some time.  I want to install a larger alternator and second battery already on my Zuk, so that is no big.  The advantage I see personally is getting rid of the belt driven compressor and freeing up space for something like a belt driven air compressor...or even keeping the factory alternator and installing a second alternator there for the second battery to keep it as a completely separate system.  I guess an issue you would have is installing the rest of the AC system in your rig, not just the compressor.  Mine would be a simple retrofit to the electric compressor.

I've posted this on a couple of other Suzuki Forums, but thought I might as well get as many opinions as possible..

My "86 tintop Samurai has never had AC, but as as I'm getting to be pretty old, I don't take the heat like I used to, and would like AC... I hear about the lack-luster cooling and power robbing the original AC provided.. I was just wondering how a modern electric AC compressor would work in a Sammy... I know you would have to install a larger alternator, and maybe even a second battery... I know the alternator would load up the tiny 1.3L motor, but would it be as bad as the mechanical compressor?... I'm thinking it would be using juice from the battery as well as the alternator... I have no idea about how many BTUs are required to cool down a Samurai, or how much the original AC had put out... Would this be a feasible option?...
Butch

The way I see it is that ultimately the energy to drive the compressor has to come from the "tiny 1.3L motor", so there's no way passing it through multiple conversions - rotating mechanical to electrical and then back to rotating mechanical will ever be "more efficient - your electrical compressor system is going to require 20~40% more energy just to cover conversion losses.

I have wondered for some time when electric compressors would reach the automotive market.  I for one have been intrigued by the idea for quite some time.  I want to install a larger alternator and second battery already on my Zuk, so that is no big.  The advantage I see personally is getting rid of the belt driven compressor and freeing up space for something like a belt driven air compressor...or even keeping the factory alternator and installing a second alternator there for the second battery to keep it as a completely separate system.  I guess an issue you would have is installing the rest of the AC system in your rig, not just the compressor.  Mine would be a simple retrofit to the electric compressor.

Electric compressors reached the automotive market a while back - that's what all the electric cars have - but they don't use 12V to drive the compressor, and for the same reasons that they don't use 12V for the traction motors, you can't get the kind of horsepower you need without going to higher voltages.

I am guessing that there have been advances in 12 volt dc compressor technology.  The RV industry has gone almost exclusively from absorbtion type refrigerators to 12v dc traditional refrigeration units, and they are very efficient from a power use perspective.  They also have the advantage of being variable output.  On a traditional belt driven compressor, it is full load all the time, and also its output is dependent on engine speed.  My guess is that with the electric compressor, you would have better idle/low engine speed AC performance, and less load when at higher engine speeds.  It would have more consistent AC performance over a broader range of engine speeds and driving conditions.  But Fordem, you are right, the "power" or "force" to run the air conditioner has to come from somewhere, it will not just magically appear.

I agree with both of you... I was just thinking like Jollyzuk, that the constant load on the engine with the old designed mechanical vs the new variable and as "needed" compressor might be more efficient...But Fordem is right, the conversion from mechanical to electrical, and back to mechanical would be inefficient... I know they put these systems, as add-ons in race-cars, big-rigs and collector cars, but may not be practical with our tiny motors... I'm just doing a little "what if"...
Butch

If I had a vehicle not equipped with A/C, I think the electric compressor might be a good option.  Something to consider in all of this...if you adapt a factory setup, you are using a 40 year old compressor design.  There have been advances in efficiency of all vehicle systems, including HVAC.  If you are comparing apples to apples, then you would be using a belt driven compressor with modern design and comparing that to a modern electric compressor.  The big question is whether or not the Suzuki compressor if variable output or not.  They became common in the late 80s into the 90's.  The improvements in efficiency would be much less or negligible compared to this style of compressor.
One thing that peaks my interest would be the ability to leave the AC running in my vehicle, without the engine running.  Of course, you would need battery capacity for this, but I plan that for my rig anyways.  Just imagine, turn off your engine, lock it up, and leave the ac blowing while you run into the store!
As far as the alternator situation...You already have an alternator operating in your vehicle, causing drag on the motor.  By upgrading to a larger alternator, you are not starting from zero power drag.  I would venture to say that there is a minimal difference in power drag for the stock alternator and an aftermarket high output unit.  I have seen dyno testing on engines that have shown a 1 hp or less drag on an engine with a 100a or so alternator installed.  I have been looking at electric power steering conversions for another project I am working on, but this gets me to wondering about just converting the PS to electric also.  Massive electrical upgrades are on the list for my rig, so the charging system and batteries would already be in place to make these retrofits.
Another thing to consider is the availability of parts.  I am not sure what parts you need to collect to mount the factory compressor set up on a Samurai, but the electric compressor would make that easier.  Another concern I have personally is the ability to source a QUALITY replacement compressor for the failed unit currently on my Sidekick.
As is quite clear, there is so much to consider when making a modification liek this.  Good luck with your research and decision!  Keep us updated on what you decide to do!

There have been improvements in compressor design, some manufacturers have moved away from the belt driven on/off clutch style compressors to belt driven variable displacement compressors which are more efficient, but they are still belt driven.

The "drag" of an alternator is directly related to the electrical load the alternator has to supply - if you think you can run a 160A load with no more "drag" that it would a 60A load, you're in one for heck of a shock.

Last but not least - having that compressor running with the engine off here are some hard numbers - a typical vehicle a/c compressor requires between 2 & 4 hp, on a 12V system, that's 125~ 250 Amps, a typical vehicle battery is less than 100Ah, you're not going to be running that compressor for very long.

From what I have been finding online, the electric compressors are "scroll" style compressors, which apparently are the bee's knees of efficient compressor design.  The specs with them are calling for 50-60 amps on most of them.  Scroll compressors basically have 1 rotor that moves, so the number of moving parts is greatly reduced over piston style pumps.  It would be interesting to see if there are belt driven scroll pumps hitting the market.  they basically work just like a roots style blower.  They may have issues with over pressure at higher engine RPMs.  One issue I am having though, is getting concrete flow numbers on the 12 volt compressors I am finding.

Thanks for jumping in on the discussion... I doubt I'll ever do this, but I thought it as was an interesting idea... New tech is constantly coming around, and it's can be intriguing....
Butch