Electric AC Compressor anyone?

[911freek]

Hi Y'all,

I'm planning to convert my A/C from a belt-driven Sanden to an electric compressor and have a couple of questions for anyone with experience:

1. Did you need to upgrade your alternator to power the new compressor?

2. Where did you mount the unit? Did you keep it in the engine bay or relocate it, and were you happy with that decision?

Looking for any lessons learned before I dive in.

Thanks!

[SpyderMike]

Here is my go at it:

1985 AC project

It works well!

[jrwilson]

I bought the upgraded alternator and I put the compressor in the smuggler's box. Mine freezes up after running a bit, perhaps due to sensor placement but no one can send me photos of exactly where they should go. It's a bad design - the sensors should be hard mounted, not placed "roughly" in vent pipes.

On the topic of support, I can't say I'm thrilled. I've posted on their official forums and emailed. No response yet.

[Yellow]

Look up Classic Retrofit. They make electric AC kits to fit G bodies. They also sell 750 amps to power them . I’m installing one in my restomod

[47silver]

An engine driven ac porsche from what i read uses 7+ hp. That = 17000 Btu’s.
If the electric one is equivalent that would = 433 amos to run it.
Apparently electric ones get by with 6500 btu’s. But that is still 155 amos at 12volts. You need lights and spark do figure a 300 amp alternator so it lasts more than a summer

[wazzz]

Originally Posted by 47silver

An engine driven ac porsche from what i read uses 7+ hp. That = 17000 Btu’s.
If the electric one is equivalent that would = 433 amos to run it.
Apparently electric ones get by with 6500 btu’s. But that is still 155 amos at 12volts. You need lights and spark do figure a 300 amp alternator so it lasts more than a summer

The electric compressor runs continuously and varies its speed, as opposed to the mechanical engine driven compressor that can only rely on the engine speed and cycles on and off.
Also, the mechanical compressor doesn't use that much power.
7 hp would be a lot and would be much noticeable. The small electromagnetic clutch wouldn't last very long.
My standard mechanical Nippon Denso compressor doesn't feel like it is using that much power. I wish it would.

[Duc Hunter]

I hate to be that guy… But if you research Classic Retrofit air-conditioning here on pelican, there are several threads, including my own to discuss their system, the BTU it uses, the alternator requirements, their blower requirements… And in the course of doing that you will learn a lot about their AC system yes, and electric AC systems in general in our cars. The BTU question above for one has been answered many many times in those threads. Just saying.

My Classic Retrofit system would freeze easily if it was not for their electronic control unit, that has freeze protection built into it. And that freeze protection is adjustable in the ECU based on where you place your sensor and doing your own testing in your own climate under your own personal driving conditions. Again, not trying to be that guy, but reading through a few of those threads would answer 90% of the questions.

I actually looked into doing this myself and then I decided not to bother reinventing the wheel, duplicating all of the testing Classic Retrofit had to do, figuring out where to source an electronic control unit, etc. I just bought their generation one unit and I’ve never been happier, and I’m in Florida.

[wazzz]

Originally Posted by Duc Hunter

I hate to be that guy… But if you research Classic Retrofit air-conditioning here on pelican, there are several threads, including my own to discuss their system, the BTU it uses, the alternator requirements, their blower requirements… And in the course of doing that you will learn a lot about their AC system yes, and electric AC systems in general in our cars. The BTU question above for one has been answered many many times in those threads. Just saying.

My Classic Retrofit system would freeze easily if it was not for their electronic control unit, that has freeze protection built into it. And that freeze protection is adjustable in the ECU based on where you place your sensor and doing your own testing in your own climate under your own personal driving conditions. Again, not trying to be that guy, but reading through a few of those threads would answer 90% of the questions.

I actually looked into doing this myself and then I decided not to bother reinventing the wheel, duplicating all of the testing Classic Retrofit had to do, figuring out where to source an electronic control unit, etc. I just bought their generation one unit and I’ve never been happier, and I’m in Florida.

That is more or less what I was trying to say. I know the CR system is efficient, much much more than the old stock AC in our cars. I've read those threads.

[Jonny H]

Originally Posted by 47silver

An engine driven ac porsche from what i read uses 7+ hp. That = 17000 Btu’s.
If the electric one is equivalent that would = 433 amos to run it.
Apparently electric ones get by with 6500 btu’s. But that is still 155 amos at 12volts. You need lights and spark do figure a 300 amp alternator so it lasts more than a summer

Not quite. Compressor 101 - the COP rating (Coefficient of Performance) means that the cooling capacity is greater than the input power. Our compressor COP is around 3

We typically run 75A input power at 13.5 volts which is 1012 Watts. With a COP of 3 that yields a cooling capacity of 3 x 1012 = 3036W which is 10,360 BTU.

Our alternators are rated 175A.

We have power management in our ECU which reduces the compressor speed in relation to cooling demand and alternator output. This reduces the amp draw at idle to save the battery from draining.

We have well over 2000 systems in operation, 70% of them in hot climates.

Here's a video which just came out today of a guy driving the length of Portugal in 37 degree C / 100F conditions. This car runs our AC.

https://www.youtube.com/watch?v=nM6uFhMyFMU

Note:

1) the guy has the windows closed and has a passenger - he is not sweaty.

2) when he stops for gas (21:44 in the video) and shows the engine there is no compressor on the engine.

[Duc Hunter]

OP - Obviously I have the CR system. I put my compressor in the smugglers box, and I am running 2 of their their Boxster condensers in my front fenders. As a result all of my A/C lines stay in the Frunk. My engine is a 964, so I am running their alternator. I tried it at first without it. Its big advantage is that it puts out a lot of amperage at idle and low RPM, vs stock style alternators. That helps a TON when trying to cool a heated up car quickly. Driving down eh freeway, once the car cooled off (or came out of a cool garage) my stock alternator kept up just fine on hot days. Hit several stoplights though....and the cabin just got hot. I hope this helps your original question.

[911freek]

Apologies, I never negotiate - you know the value of your products.
But I am not after a full replacement of the system, and even if I was, this is out of my budget.

Originally Posted by Jonny H

Not quite. Compressor 101 - the COP rating (Coefficient of Performance) means that the cooling capacity is greater than the input power. Our compressor COP is around 3

We typically run 75A input power at 13.5 volts which is 1012 Watts. With a COP of 3 that yields a cooling capacity of 3 x 1012 = 3036W which is 10,360 BTU.

Our alternators are rated 175A.

We have power management in our ECU which reduces the compressor speed in relation to cooling demand and alternator output. This reduces the amp draw at idle to save the battery from draining.

We have well over 2000 systems in operation, 70% of them in hot climates.

Here's a video which just came out today of a guy driving the length of Portugal in 37 degree C / 100F conditions. This car runs our AC.

https://www.youtube.com/watch?v=nM6uFhMyFMU

Note:

1) the guy has the windows closed and has a passenger - he is not sweaty.

2) when he stops for gas (21:44 in the video) and shows the engine there is no compressor on the engine.

[911freek]

Thanks all, I think I will upgrade the existing compressor and wait with this until teh technology is a bit more mature and available.