Thread: 12 volt driven aircon

Sorry rencool

I just read a review of the new Hyundai EV which I presume has 12v air conditioning.
The writer commented on the inadequacy of the aircon, citing that it had to be on full belt to cool the car and even though the back seat passengers had vents they complained. So there may be a few more compromises with EVs than are broadcast.

It also reduced the proposed range from 230Km to AFAIR 180Km.

So My conclusion after one example is be careful that the BTU output is enough to cool a car.

Regards Philip A

Originally Posted by PhilipA

I just read a review of the new Hyundai EV which I presume has 12v air conditioning.
The writer commented on the inadequacy of the aircon, citing that it had to be on full belt to cool the car and even though the back seat passengers had vents they complained. So there may be a few more compromises with EVs than are broadcast.

It also reduced the proposed range from 230Km to AFAIR 180Km.

So My conclusion after one example is be careful that the BTU output is enough to cool a car.

Regards Philip A

But IIRC the car with 5 passengers on board did cool down after a few km (by cold blasting the front passengers until equilibrium) - which is no different to most cars that have been sitting in the hot outside before being driven off, so maybe not write that level of option off just yet.

I've been watching this thread hoping someone will post something awesome! I don't have the spare coin to put a rencool system in, but I'm looking for something 12v driven as well for a project.

Anyone here actually had experience with using an electric car AC compressor? I have to hit up google!

I wont spend $5 to $6k to do the job either, nearly what it cost me for the old coaster. I am still looking at options. Maybe strip down and reinvent a household invertor system and run it of an invertor
cheers
blaze

Why not use a normal vehicle AC compressor, but drive it from a 12V motor instead of the engine? You can mount it pretty much anywhere, but close to the batteries would be best. There will be additional energy losses due to the belt drive though.

All pretty pricey still unfortunately

12 V Electric Air Conditioning Compressor – How Can You Decide Which One is Right For You?

HVAC is a complex subject involving many variables, be it air conditioning or refrigeration.

It is basically a matter of energy conversion, and how it is converted to useful work.
Airconditioning compressors, like most other compressors, have a useful output calculated on the displacement and RPM.

An engine driven A/C compressor in a car is not driven at a constant speed, so it is not possible to state what the output is going to be in BTU's, or any other measure, except to say that the output is going to be a lot more at high engine RPM than it is at idle speed, and continuously variable.

Rather than try and write a basic explanation the following has been stolen:


https://www.quora.com/What-is-the-typical-nominal-cooling-capacity-kw-or-BTU-h-of-a-car-air-conditioning-device


A7.2cc/rev R134a compressor operating as HBP at 2100 RPM has a capacity of 2,076BTUs per hour.
Breaking that down:
7.2 cubic centimeters pumped per revolution.
HBP is air conditioning or dehumidifier conditions. (High BackPressure type)
That gives a capacity of 288 BTU/Hr per CC/REV at that speed.
Dividefurther by 2100 RPM is .137 BTU/Hr per CC/REV per RPM
My Geo Tracker/Suzuki Sidekick uses a relatively small Denso10P08E compressor which is 7.6CC/REV. It is roughly 3000 RPM cruising. Thatgives an educated guess as roughly 30k BTU AKA 2.5 tons capacity. At idle speedthat’s less than 1 ton capacity.
Youcan run the numbers for any other vehicle that you can find the idle and cruiseRPMs, pulley ratio to get compressor RPMs, and compressor displacement.
…………………………………………†¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â €¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦

As an old fart, lets stick to old measurements:

The BTU's per hour unit number 2,544.43 Btu/h converts to 1 hp ie, one Mechanical horsepower. It is the EQUAL power value of 1 Mechanical horsepower but in the BTU's per hour power unit alternative.

Since 1 hp equals 746 watts, and volts x amps in this case = watts, and watts divided by volts = amps, we have 746 divided by 12 = 62 amps. (will vary slightly with system voltage)

1,000 watts = 3,412 BTU.

So, I am not sure how Rencool come up with 35 - 55 amps, even using a brushless motor and BLD controller? Even at 24 volts?