Cool/Heat: Electrical AC systems

[shanefausett]

Does anyone have experience with 12V electrical AC systems? They have an electrical compressor so you do not have to mount the compressor to your engine. Summer is coming and I know my wife won't want to ride in my lark without AC. Or failing that what recommendations are there out there for adding AC to my Lark ?

[shanefausett]

D'oh no edit ....
Here is a link to a system I found on AliExpress. Fairly inexpensive way to get AC it seems.

https://www.aliexpress.us/item/3256804888862255.html?spm=a2g0o.detail.pcDetailTopMoreOtherSeller.5.4114mE5nmE5n0T&gps-id=pcDetailTopMoreOtherSeller&scm=1007.40000.327270.0&scm_id=1007.40000.327270.0&scm-url=1007.40000.327270.0&pvid=38237bff-b35a-4271-b2d6-8085f541654e&_t=gps-id:pcDetailTopMoreOtherSeller,scm-url:1007.40000.327270.0,pvid:38237bff-b35a-4271-b2d6-8085f541654e,tpp_buckets:668%232846%238111%231996&pdp_npi=4%40dis%21USD%21558.60%21335.16%21%21%214001.40%212400.84%21%402103011417089149525746820eb3cf%2112000031538446675%21rec%21US%21%21AB&utparam-url=scene%3ApcDetailTopMoreOtherSeller%7Cquery_from%3A

[gordr]

Interesting. They claim the cooling output is 3000 Watts. Compressor is 20cc displacement. I am flat-out guessing here, but my guess is that the compressor draws no more than 50 amps from a 12 volt system, so 600 watts of electrical power. That's probably about half the power of a window-mount home AC? To run it in any Studebaker, you'd have to install a bigger alternator, and upgrade to dual-sheave pulleys, I expect.

[shanefausett]

My stude is LS swapped. I have a beefy alternator and can even get a bigger one if I need. I am thinking of building a box that lives under the dash and over the transmission hump. I would put the AC evaporator in the box as well as perhaps an android auto stereo with a back up camera. I would paint and upholster the box to match the interior of the car.

[Lark Hunter]

Your Alibaba link takes me to a page written in Cyrillic, so I can't pick up any details from that. I've never seen electric aircon in a non-electric or hybrid vehicle. Aside from being able to eliminate the troublesome front seal of a belt driven compressor, I see no advantages to using electric A/C, and a lot of disadvantages. I've never encountered wattage being used as a measure of system output, but if we just run with that number and say that it's 100% efficient to make the math quick and easy, 3000 watts is 250 amps at 12 volts.

I poked around online a little bit, and am finding a lot of products with very cryptic specifications. There's one that says it requires 70 amps (at 12 volts) to start and 600 watts in normal operation, but conveniently leaves out its BTU output. The reason for this is that its real world output is probably enough to cool a glove box on a 100 degree day. I've got a 14,000 BTU window air conditioner that requires 11.5 amps at 120 volts... so 1380 watts. 14,000 BTU is probably the bare minimum for automotive A/C; I'd prefer to see 25,000 BTU. This is putting us at ~115 amps at the lowest, and up to 200-250 to actually keep your cool. Figure in that your absolute highest cooling demand is going to be when starting off in your car after it's been heat soaking in a parking lot and the interior is 145 degrees, or when you're idling in rush hour traffic... and that alternators don't reach maximum output until you're a bit above fast idle. You should have room for a second alternator in the place vacated by the A/C compressor your LS wore in its former life, so there's that.

[bensherb]

" I've never seen electric aircon in a non-electric or hybrid vehicle."

The gen 2 Prius (they're up to gen 4 maybe 5 now) uses an electric AC compressor. It runs on 200+ volts at around 17 amps and can run 7500 rpm. It's a 3 phase syncronous motor, modulated by the inverter, based on control from the HV ECU.

[Lark Hunter]

Oops. That was a little muddy and I should clarify: "I haven't encountered electric A/C in a vehicle that is powered by combustion engine only. All have been either pure electric, or have some type of hybrid system with a high voltage battery."

An electric HVAC system makes a lot of sense in a hybrid vehicle, as it will allow you to keep cool without having to run the engine 100% of the time when cooling is requested. While 17 amps at 200 volts is 3400 watts, there are a lot of times when your cooling load will be much lower... like maintaining an already cool cabin in indirect light on an 85 degree day. Summer temperatures can be close to 100 degrees at night in Arizona, and though I'm running A/C all night, it's loafing along at about 1/3 of the energy input required at high noon. Having an inverter system is great, as it can ramp up the compressor slowly and run it at whatever speed is necessary, instead of the binary, compressor ON or OFF operation of an old school system. All of this plays well with reversing the compressor rotation to use it for cabin heating on pure EV's, though I'm sure most hybrids use waste heat from the combustion engine for those duties... an electric water pump will facilitate the flow of coolant without needing to idle the engine to pump it around.

[greyben]

A rough number for ac would be 10,000 btu output for 1000 watt input. A modern whole house unit can provide in excess of 15000 btu/kw. An automotive unit could provide somewhat less. 1000 watts would equate to about 75 amps at 13.5 volts.