Electric air conditioner - PeachParts Mercedes-Benz Forum

Treeman · #1 05-25-2010, 10:18 PM

I am looking for information on a total electric air conditioner for my 77 240d.
Has anyone ver heard of such an animal?

mpolli · #2 05-26-2010, 04:43 AM

http://www.engadget.com/2007/08/11/grad-student-bolts-air-conditioner-onto-car-to-beat-texas-heat/

Gilly · #3 05-26-2010, 05:07 AM

The engine is the logical power provider for an AC compressor. The only way I can think of to have an AC system is they way they install them at the factory, so it makes sense to just go with that type of system. You could try running the AC compressor with an electric motor, and even relocate the compressor if you wanted to. Early AC systems (40s, 50s?) the system was in the trunk, no idea what powered the compressor or where it was.
Gilly

#4 05-26-2010, 07:18 AM

This thread is a joke, right?

TX76513 · #5 05-26-2010, 08:48 AM

Quote:

Originally Posted by LarryBible

This thread is a joke, right?

Not - we use them on our electric buses

You can get them at Shoppas in FWTX

jcyuhn · #6 05-26-2010, 10:18 AM

I agree with Larry - this is a joke.

Save your time and drop it right now. The electrical system of a 123 does not produce enough power to drive an a/c compressor that would supply anything like sufficient cooling. A 2 ton a/c compressor (typical size for a car) consumes 300% more electricity than the alternator of a 123 is capabile of producing.

TX76513 · #7 05-26-2010, 10:24 AM

Electrics have come a long way - if you haven't been around one in the last couple years it will suprise you. Most of the technology has come from mini subs and such and of course NASA.

Also the AC unit in a W126 is rated at 6500 BTU 2 Ton = 24000 BTU's

#8 05-26-2010, 10:56 AM

The trend in over the road diesel tractors is moving toward electric units. I get it! But the 123 is not a Bus nor a Peterbilt.

If that graduate student in the linked article is an engineering student, we're doomed.

TX,

Where do you get the 6,500 BTU number?

tjts1 · #9 05-26-2010, 11:34 AM

All hybrids have electric AC compressors so they can keep running the AC when the engine is off.

http://cgi.ebay.com/ebaymotors/A-C-AC-COMPRESSOR-04-05-06-07-08-09-TOYOTA-PRIUS-_W0QQcmdZViewItemQQhashZitem3eface56c9QQitemZ270495798985QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

http://cgi.ebay.com/ebaymotors/04-05-06-07-08-09-Prius-A-C-AC-Compressor-38K-OEM-LKQ-_W0QQcmdZViewItemQQhashZitem5ad9cb4dd0QQitemZ390201036240QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

jcyuhn · #10 05-26-2010, 12:03 PM

Quote:

Originally Posted by tjts1

All hybrids have electric AC compressors so they can keep running the AC when the engine is off.

http://cgi.ebay.com/ebaymotors/A-C-AC-COMPRESSOR-04-05-06-07-08-09-TOYOTA-PRIUS-_W0QQcmdZViewItemQQhashZitem3eface56c9QQitemZ270495798985QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

http://cgi.ebay.com/ebaymotors/04-05-06-07-08-09-Prius-A-C-AC-Compressor-38K-OEM-LKQ-_W0QQcmdZViewItemQQhashZitem5ad9cb4dd0QQitemZ390201036240QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

Yes, hybrids do. And hybrids have high voltage NiMH or Lithium battery packs which can supply thousands of watts of power to run the electric a/c. And hybrids have electric motors/generators that can produce large amounts of electricity. A 123 has neither of those things.

The 6500BTU number above doesn't feel right. That is a small window air conditioner. Compared to the volume and cooling available from an automobile - even an old Benz - I don't believe it is correct. I've always heard 1-2 tons (12K-24K BTU/Hr) for automotive air conditioners.

A typical home central air compressor consumes approximately 1000 watts per ton. Let's assume the electric automotive compressor is the same efficiency, and that you want 1.5 tons of cooling for the 123. So you need 1,500 watts of power. At 13 volts, that means the a/c compressor is drawing 115 amperes of current.

Most 123 models came with a 65 ampere alternator. Are you seeing the problem here?

ILUVMILS · #11 05-26-2010, 12:13 PM

http://www.engadget.com/2007/08/11/grad-student-bolts-air-conditioner-onto-car-to-beat-texas-heat/

#12 05-26-2010, 12:38 PM

Okay Jim, there you go again! Cluttering up the discussion with facts! You're letting a few Basic Electronics 101 calculations get in the way of creative engineering!

TX76513 · #13 05-26-2010, 12:46 PM

Quote:

Originally Posted by jcyuhn

Most 123 models came with a 65 ampere alternator. Are you seeing the problem here?

No don't see it. If I were to that the alternator wouldn't be part of the equation.
There only is that one question in the original post:
I am looking for information on a total electric air conditioner for my 77 240d.
One can only make assumptions to what the intended use might be. My general thought is I wouldn't do it as it would have to be cheaper to replace the entire CCU in the D then to make to revolutionize it with electric AC

On total electric vehicles the heating/AC in controlled by a seperate bank of batteries and is charged when the vehicle is plugged in for a normal recharge cycle or if equiped with a extended range genset. 12/24VDC with AMP rating as low as 5

The largest BTU rating AC I can find in the MB line up is the Sprinter @ 13,500btu's

tjts1 · #14 05-26-2010, 01:02 PM

More electric AC
http://www.masterflux.com/products/sierra/

Quote:

Originally Posted by jcyuhn

I've always heard 1-2 tons (12K-24K BTU/Hr) for automotive air conditioners.

I don't know where that number came from but thats going to put your car into a very deep freeze. 8000 btu for 800w should be more than reasonable for a car. The only issue is providing the proper voltage. It'll require its own dedicated 50v battery and charging system. Its possible but why?

#15 05-26-2010, 02:04 PM

Quote:

Originally Posted by TX76513

No don't see it. If I were to that the alternator wouldn't be part of the equation.
There only is that one question in the original post:
I am looking for information on a total electric air conditioner for my 77 240d.
One can only make assumptions to what the intended use might be. My general thought is I wouldn't do it as it would have to be cheaper to replace the entire CCU in the D then to make to revolutionize it with electric AC

On total electric vehicles the heating/AC in controlled by a seperate bank of batteries and is charged when the vehicle is plugged in for a normal recharge cycle or if equiped with a extended range genset. 12/24VDC with AMP rating as low as 5

The largest BTU rating AC I can find in the MB line up is the Sprinter @ 13,500btu's

Again TX, where are you findinig this number?

I don't know where Jim is getting his number either, but back in a vendors school that I went to over 30 years ago, they were saying that it took a couple of tons of a/c capacity for a car due to the extreme heat involved after setting in the Sun all day plus all the heat generated by the drivetrain plus all the heat drawn from the air on a hot day going down the road. Additionally I googled around for a few minutes and was finding numbers in the 20,000 BTU area.

Where are you finding the BTU ratings for the MB models?

Also TX I'm not following you when you say that the alternator is not part of the equation. Please expound.