Electric A/C anyone?, Comments, dialog, experience? Options

[burton73]

On Elwood (the original six) I have considered upgrading the alternator, and adding a small 12v RV rooftop AC unit to a spare targa top. Drop the wiring down to the battery, and you get cold air in the car without cutting up the front trunk.

Yea, it would look a bit silly, but it could be easily removed and replaced with the stock, unaltered top.

And it Texas, AC is not a luxury. It is a necessity.

But I have to get this idea by the co-owner of the car. (IMG:style_emoticons/default/driving-girl.gif)

@ClayPerrine

Clay, this is not a bad idea in a pinch. Plenty of tops for 914s but you may get a cerebral freeze out. Still around 5 inches tall.

Best Bob B

[mepstein]

Paint it black and it will look like a small cargo top.

[Shivers]

It’s a Gurney Bubble to fit my fat head. That’s my story

[Highland]

Could one use a battery to power the compressor and fans? It would be an additional 60 lbs. or so and one would have to remember to charge it, but no additional load on our sub 100Hp engines.

[mepstein]

Could one use a battery to power the compressor and fans? It would be an additional 60 lbs. or so and one would have to remember to charge it, but no additional load on our sub 100Hp engines.

You would have to run the numbers but I’m betting 60lbs of batteries would equal about 15 minutes of a/c. I could be off but no way is a battery going to last for a decent drive time.

[VaccaRabite]

I'm not up enough on /6 stuff to know about their alternators.

I have the 175A alternator on my 930 from the Classic Retrofit eAC system. After installing the alternator I noticed voltages below 12V at low idle. After some investigation it turns out the engine needs to be above 1k rpm for the alternator to produce adequate voltage.

Swap the pully on the alternator to get it to spin faster? Would that have it overspinning at 5500 rev?

Zach

[Root_Werks]

Could one use a battery to power the compressor and fans? It would be an additional 60 lbs. or so and one would have to remember to charge it, but no additional load on our sub 100Hp engines.

You would have to run the numbers but I’m betting 60lbs of batteries would equal about 15 minutes of a/c. I could be off but no way is a battery going to last for a decent drive time.

Isn't that sort of what the Honda CRZ did? My kid had one years ago. He said there was a second battery accessories like AC ran off. That would be a few hundred pound battery I would think.

[Chris914n6]

Regardless of cabin size, using a stock 3.2 alternator is inadequate- BTDT

@mepstein I thought I had read the 3.2 has a larger alternator, yet still not enough?

Nope. You need at least 100 amps just for the AC unit. IIRC the 3.2 alternator is like 90 amp. So you need a 190 amp alternator. I know there is a 175 amp alternator available for it, but you would need to put a smaller pulley on the alternator or a bigger crank pulley so it turns faster. That will probably make it work OK. And it will have an additional effect of speeding up the fan. Which is better in hot climates.

The alternator for a 3.6 is 180 amp. If you could use it with the 3.2, it would be ideal. but I don't think it will fit the fan shroud.

Your math is off. If you use LEDs (specially headlights) and no stereo then power needs will be quite low, not the 90A of an 80s 911.
So if the engine needs 10a to run, plus 40a for the comp on low, plus 6a for the blower, plus 6a for the condenser, then you are within limits of the stock alt.

You might need to set idle at 4000rpm though...

@steve All evap units are made in China now.
Save the markup and just buy one off Amazon that fits your liking.

[Highland]

Could one use a battery to power the compressor and fans? It would be an additional 60 lbs. or so and one would have to remember to charge it, but no additional load on our sub 100Hp engines.

You would have to run the numbers but I’m betting 60lbs of batteries would equal about 15 minutes of a/c. I could be off but no way is a battery going to last for a decent drive time.

Isn't that sort of what the Honda CRZ did? My kid had one years ago. He said there was a second battery accessories like AC ran off. That would be a few hundred pound battery I would think.

So maybe I'm showing my ignorance, but a 60A compressor running 4 hours is 60 Ah. 80% of a 300 Ah battery is 240 Ah or 4 hours of compressor run time; so 3 hours of compressor run time at the low end. A 300 Ah Lithium Iron Phosphate battery weighs less than 60 lbs.

Is this correct or am I missing something?

https://www.renogy.com/core-mini-12-8v-300a...ure-protection/

[mepstein]

Regardless of cabin size, using a stock 3.2 alternator is inadequate- BTDT

@mepstein I thought I had read the 3.2 has a larger alternator, yet still not enough?

Nope. You need at least 100 amps just for the AC unit. IIRC the 3.2 alternator is like 90 amp. So you need a 190 amp alternator. I know there is a 175 amp alternator available for it, but you would need to put a smaller pulley on the alternator or a bigger crank pulley so it turns faster. That will probably make it work OK. And it will have an additional effect of speeding up the fan. Which is better in hot climates.

The alternator for a 3.6 is 180 amp. If you could use it with the 3.2, it would be ideal. but I don't think it will fit the fan shroud.

Clay - check that 964 alternator amperage. I believe it’s only ~ 115 amps. We use the wosp alternators on 3.6 engines. I just did one last week. @clayperrine

[Root_Werks]

Could one use a battery to power the compressor and fans? It would be an additional 60 lbs. or so and one would have to remember to charge it, but no additional load on our sub 100Hp engines.

You would have to run the numbers but I’m betting 60lbs of batteries would equal about 15 minutes of a/c. I could be off but no way is a battery going to last for a decent drive time.

Isn't that sort of what the Honda CRZ did? My kid had one years ago. He said there was a second battery accessories like AC ran off. That would be a few hundred pound battery I would think.

So maybe I'm showing my ignorance, but a 60A compressor running 4 hours is 60 Ah. 80% of a 300 Ah battery is 240 Ah or 4 hours of compressor run time; so 3 hours of compressor run time at the low end. A 300 Ah Lithium Iron Phosphate battery weighs less than 60 lbs.

Is this correct or am I missing something?

https://www.renogy.com/core-mini-12-8v-300a...ure-protection/

Eh, I'm probably talking out my arss-hole and simply don't remember. Been too many years since the kid had that car. I do remember riding in it, was like any regular stick shift car. I had to google it, looks like the CRZ is somewhat electric motor propelled. So my battery weight estimate wouldn't be correct.

-Dan

[Chris914n6]

It's a typical hybrid. So there is the traction (drive) battery of 240v or more, and there is a standard 12v battery to run the usual car electrics like gauges, windows, locks, lights, ecu & bcm. The compressor would be run normally by the engine or the 240v battery.

[Steve]

I did some more testing at 70 degrees in the garage. At the medium setting (65 amps) I get around 38 degrees at the vent. With the low setting (42 amps) I get around 42 degrees at the vent. Since my stock 3.6 alternator is only 115 amps, I will leave it at the low setting until I upgrade the alternator some day. Since the evaporator is an under dash unit, it will recirculate the air anyway.
I love the under dash evaporator. Doesn’t take that much room.
https://www.southernrods.com/cooling-and-he...-unit-only.html

[Steve]

This looks like my compressor on Amazon. https://a.co/d/hig07IG

[mate914]

Hi
Can I see a pic of the under dash evaporator in the car?
Matt

I did some more testing. At the medium setting (65 amps) I get around 38 degrees at the vent. With the low setting (42 amps) I get around 42 degrees at the vent. Since my stock 3.6 alternator is only 115 amps, I will leave it at the low setting until I upgrade the alternator some day. Since the evaporator is an under dash unit, it will recirculate the air anyway.
I love the under dash evaporator. Doesn’t take that much room.
https://www.southernrods.com/cooling-and-he...-unit-only.html

[nditiz1]

Adding some facts into this thread.

The CR AC will run off of the 3.2 90amp stock alt. What happens at idle is the compressor will cycle a lot more almost instantly. I have the CR(WSOP) in my 77 targa and if at a light for more than a 1min 30 sec it will cycle. If I keep the revs higher than 1500 it will not cycle off. Also, you will be limited by how much you can force the compressor to work. If memory serves me I have pulled close to 90amp blasting the AC and other 911 functions during peak times.

Now, the half kit is probably the best setup unless CR has developed 914 specific kit. The half kit is only including the compressor and 1 fan/condensor. You will still need to figure out the evaporator and blower. Ideally you could hook it into the aftermarket 914 underdash setup.

If you wanted to use the CR kit with a 4cyl, I think it could be done with a higher output 90amp alt OR even better is the HO alt kit that I have seen on here before. I want to say it was a 200amp bolt on kit. That would generate a ton of needed power for the setup.

[Superhawk996]

So maybe I'm showing my ignorance, but a 60A compressor running 4 hours is 60 Ah. 80% of a 300 Ah battery is 240 Ah or 4 hours of compressor run time; so 3 hours of compressor run time at the low end. A 300 Ah Lithium Iron Phosphate battery weighs less than 60 lbs.

Is this correct or am I missing something?

You’re missing a lot of nuance about the difference between energy and power. Lithium batteries are great at delivering high energy (ie high current) for a short duration. Lithium batteries are not great at maintaining high current draws at rated voltage (ie power) over long periods of time.

Actual battery capacity is often much less than rated capacity - especially under situations where power demand is high. An example of this would be an EV with say a 200 miles of real world range. Now put it on a race track and ride it like a rented mule - you won’t get anywhere near 200 miles on the track.

YMMV

[Superhawk996]

It's a typical hybrid. So there is the traction (drive) battery of 240v or more, and there is a standard 12v battery to run the usual car electrics like gauges, windows, locks, lights, ecu & bcm. The compressor would be run normally by the engine or the 240v battery.

(IMG:style_emoticons/default/agree.gif)

EVs run the compressor off the high voltage battery.

[JmuRiz]

Hi
Can I see a pic of the under dash evaporator in the car?
Matt

I did some more testing. At the medium setting (65 amps) I get around 38 degrees at the vent. With the low setting (42 amps) I get around 42 degrees at the vent. Since my stock 3.6 alternator is only 115 amps, I will leave it at the low setting until I upgrade the alternator some day. Since the evaporator is an under dash unit, it will recirculate the air anyway.
I love the under dash evaporator. Doesn’t take that much room.
https://www.southernrods.com/cooling-and-he...-unit-only.html

Check post #20 on page one of this thread.

[Steve]

Hi
Can I see a pic of the under dash evaporator in the car?
Matt

I did some more testing. At the medium setting (65 amps) I get around 38 degrees at the vent. With the low setting (42 amps) I get around 42 degrees at the vent. Since my stock 3.6 alternator is only 115 amps, I will leave it at the low setting until I upgrade the alternator some day. Since the evaporator is an under dash unit, it will recirculate the air anyway.
I love the under dash evaporator. Doesn’t take that much room.
https://www.southernrods.com/cooling-and-he...-unit-only.html

Here’s a couple more. It is a little into the passenger side. I added a second battery in my troubleshooting, to see if the long wire to the battery was the problem. It wasn’t the problem, but I left it anyway. My original problem was the pressures were all over the place and it would trip my 100 amp breaker. I originally took the same evaporator, ripped the guts out and mounted it on its side in the center console. It was a nice setup, it didn’t work. You can click on my blog for pictures of that setup.
Next, I will install a cut down deposit box underneath it and mount the controls underneath the evaporator.