How much would you estimate it would cost to have a car that isn't a hybrid, modified to have it's A/C compressor and blower run on batteries whenever the car would be idling for a while.

I would like to have a gauge to check energy consumption and battery levels.

I wouldn't mind plugging it in at night, so I wouldn't kill the battery.

I have a custom wound extremely heavy duty alternator in there already, so that's a very small piece of the puzzle done.

Any ideas?

[Edited on June 23, 2007 at 11:33 AM. Reason : it's a honda accord by the way.]

6/23/2007 11:32:49 AM

electrically driven a/c compressors consume a LARGE amount of power, especially at startup. i would reccomend a deep cycle setup. golf cart batteries are the cheapest bang for you buck. they are 6v, so you'll need to buy them in pairs and wire them accordingly.

other than that, you just need to do the math on whatever compressor setup you choose as to the amps/watts the system needs to handle.

you might want to take apart a home window unit and trying to adapt that with an inverter.

as for what it'll cost to run, i have no idea. i can't imagine it being much if any more economical than a conventional setup though, especially after you spend the time/money making it.

6/23/2007 11:51:48 AM

interesting. home window unit? i just saw one in the store that runs off 120v. so that's a possibility.

i just wanted something that i didn't have to keep the engine running for.

i guess you can't really pick and choose what you want to be electric. in a perfect world, i'd like to disconnect the belt driven compressor and attach an electric motor to the clutch. i guess it would be really hard to find a space to put it without doing crazy mods to the plumbing and all.

whoever on here that had a truck with a window unit seemed like a decent idea, that would be much easier. i guess you could leave the unit in the bed and run a vent to the rear window so that you could keep the unit from smashing in the back of your head if you stopped too hard. leave the batteries in the bed beside it and run the wires for the guages in the cab.

i just need to find a small toyota pickup to mod.

6/23/2007 1:22:09 PM

Why do you want to do this?
Ahmet

6/23/2007 1:33:37 PM

buy a compressor which runs off DC, i think a few cars have them now.



building an inverter to power a window unit is one of the dumbest things ive ever read

do you know how much power youre going to need? Even with a miricle inverter youre going to be burning 100W+ in a converter.

6/23/2007 5:19:19 PM

im guessing that for this to pay for itself you will have to drive the car for longer than you will be alive

6/23/2007 6:13:59 PM

ive actually seen a truck that have a window unit mounted in the rear window with an inverter powering it.

don't forget you'd have to install a relay to your electric fans to switch them on also so they can draw air through the condenser.

6/23/2007 8:32:22 PM

Quote :

"im guessing that for this to pay for itself you will have to drive the car for longer than you will be alive"

It would be physically impossible for the electric A/C to be more efficient than a system that takes it's energy from the internal combustion engine's power, provided that the said engine provides the means necessary for the electric power that the A/C system uses. There's always conversion losses, even with hyper efficient converters.
Ahmet

6/23/2007 9:19:41 PM

do you know how big a 7 hp electric motor is ?

6/23/2007 9:46:45 PM

If you really want to save that much HP, just buy a 8 HP B&S engine and run it seperatly.

6/23/2007 11:28:32 PM

1st you'll need 3 Φ 208, 230 or 460 in your car cause 12v dc would draw a ridicules amount of amperage. and then you need about 1.5 cubic feet of free space to mount a nearly 200lb motor.

6/24/2007 8:48:28 AM

6/24/2007 12:42:22 PM

^^ you wont need fucking 3 phase

hell your god damn single family house units only run on 240V single phase and they are in the 1 ton + range

a window unit will run on 120V single and not trip a 20 A breaker

[Edited on June 24, 2007 at 1:00 PM. Reason : 

6/24/2007 12:59:39 PM

because automobile hvac systems are every bit as efficient as a home hvac system....
you know rejecting heat to an atmosphere that already has a large heat source and another heat exchanger near by is every bit as efficient as one that is typically isolated from heat sources and has its own fan and is at least 5 times the physical size.



btw.. this is a fairily typical auto a/c compressor.
used in things from volvos to dodge trucks.

6/24/2007 2:02:54 PM

Quote :

"because automobile hvac systems are every bit as efficient as a home hvac system.... you know rejecting heat to an atmosphere that already has a large heat source and another heat exchanger near by is every bit as efficient as one that is typically isolated from heat sources and has its own fan and is at least 5 times the physical size."

oh fucking blow me

he doesnt need fucking three phase power

this whole idea is stupid anyway

the only advantage would be a more efficient ac system because you could run it at its best speed for the load you need all the time, rather than tied to the engine speed

6/24/2007 3:11:17 PM

Quote :

" do you know how much power youre going to need? Even with a miricle inverter youre going to be burning 100W+ in a converter."

while i would hardly reccomend building an inverter himself, there are plenty made in the 4-5kw range that are more than capable to handle the loads of a smaller a/c unit.

[Edited on June 24, 2007 at 4:48 PM. Reason : .]

6/24/2007 4:48:14 PM

^^ hahah OHH BURNED...
btw go to grainger all 5hp+ motors are 3 phase.

6/24/2007 5:40:09 PM

Quote :

"you know rejecting heat to an atmosphere that already has a large heat source and another heat exchanger near by is every bit as efficient as one that is typically isolated from heat sources and has its own fan and is at least 5 times the physical size."

Well the heat exchanger for the A/C units on cars are mounted upstream of the radiator, and air flows through the engine radiator after it goes through the A/C unit. If there was such a loss, the heat exchanger for the A/C could've been placed elsewhere from the factory, yet it's universally placed ahead of engine radiators.

On virtually every car/truck, etc. A/C compressors are driven by the mechanical power of the engine, thereby not subject to energy losses involved in converting the engine's mechanical energy into electricity, only for the electricity to be used to convert back to mechanical energy (to drive the compressor). Every time energy is converted, there are losses (typically quite large).

I'm not an expert in A/C systems, but it doesn't make sense to convert the energy back and forth, especially when the final type of energy to be used (mechanical) is the same as the starting type. I imagine if this were not the case, manufacturers would already be investigating ways to build more efficient A/C systems utilizing electric compressors. Even hybrid cars are not using electric A/C compressors. Infact, all pumps/fans are capable of being more efficient if they're mechanically driven. The only pumps that have been eliminated in the name of efficiency in recent years are the power steering pumps, but only because manufacturers have been able to use electromagnetic steering racks, thereby directly using electric power. Fans have gone to electric for most engines, but that is because more energy can be saved when switching off a fan, or running it at a different speed (A/C clutches accomplish the on/off regulation of the compressor just fine).

Correct me if I'm wrong.
Ahmet

6/24/2007 5:58:09 PM

you're wrong, but I'm not correcting you... jk

6/24/2007 6:14:00 PM

Quote :

"It would be physically impossible for the electric A/C to be more efficient than a system that takes it's energy from the internal combustion engine's power, provided that the said engine provides the means necessary for the electric power that the A/C system uses. There's always conversion losses, even with hyper efficient converters. Ahmet "

He is right.

Your best option would be to charge some deep cells off grid power while parked at home.

Any grid based power scheme is going to be leaps and bounds more efficient than a car engine.

6/24/2007 6:50:40 PM

if only there was some kind of a non air conditioned, underpowered car that had been around for decades, with a huge aftermarket following, perhaps someone has already developed this electric AC??





the important question however is why in the hell do you need to do this seotaij?

6/24/2007 7:48:49 PM

Quote :

"btw go to grainger all 5hp+ motors are 3 phase."

well that would probably be so because it is an industrial supply company

i wonder who they are supplying?

oh yeah

people that bleed 3 phase...industry

6/24/2007 9:59:23 PM

Quote :

"Even hybrid cars are not using electric A/C compressors"

Im fairly certain the prius uses an electric ac compressor. Even if is being driven by the electric motor it will technically qualify.

It might also be running off an dc/ac inverter. I think they have a source of upwards of 200V on the battery pack though.

[Edited on June 24, 2007 at 11:42 PM. Reason : .]

6/24/2007 11:40:35 PM

The Prius switched to an electric A/C compressor with the current body style, as the internal combustion engine is meant to be powered off as often as possible. However, you still raise a good point, it's not belt driven, purely electric powered. This casts some doubts in a part of my reasoning.
Ahmet

6/25/2007 12:44:14 AM

well when your dc starting point is 200V, as opposed to 12V youre on the right path.

Its hard to pass 10 times more amps through anything without it getting hot as a mother fucker.

6/25/2007 8:13:05 AM

your typical compressor draws 5-7 hp, which would require a 50-70 amp motor at 12v dc

that would drain your typical deep cycle battery in 52 minutes

Quote :

"btw go to grainger all 5hp+ motors are 3 phase"

thats because they are significatly more efficient than single phase, and most of them are 230/460 motors due to high power demand, you typically don't see many single phase motors over 30 FLA, @230V, plus most starters and switchgear are designed for 3 phase, point is, it doesnt matter, because he is talking about DC, and i haven't seen one of those AC batteries lately

[Edited on June 25, 2007 at 9:27 AM. Reason : blah]

6/25/2007 9:21:18 AM

We've got a few high hp (5-10) single phase motors

6/25/2007 11:16:36 AM

Quote :

"the important question however is why in the hell do you need to do this seotaij?"

i woke up the other day wanting to know if it were possible to retrofit it onto a car so that i could sit with the a/c on in traffic or otherwise without wasting gas. if it could be done cheaply, i was all for it b/c i love tinkering with anything, but I HATE to waste money on something that won't work.

plus i have a kid and it's summer. i want to keep the car cool so that he's not uncomfortable before we get in and it takes a while for the a/c to really work. i'm not interested in remote start as i'm concerned with theft/wasting gas. i'd like to be able to run a retractable power cord to the car at night to recharge the batteries and power the system before we depart (i.e. remote cooling).

there has been some great discussion in this thread.

Quote :

"your typical compressor draws 5-7 hp, which would require a 50-70 amp motor at 12v dc that would drain your typical deep cycle battery in 52 minutes"

that's good to know, as i'd never sit longer than 30 mins. the weight of all the assorted items needed would probably negate the fuel savings, but i'm still curious to see if it is viable in any way.

[Edited on June 25, 2007 at 12:47 PM. Reason : eh]

[Edited on June 25, 2007 at 12:47 PM. Reason : eg]

6/25/2007 12:43:56 PM

Quote :

"i'm not interested in remote start as i'm concerned with theft/wasting gas"

i don't see how theft is an issue as usually you would have to have a key in the ignition to actually drive the car.

gas wasted to let the car idle for a few minutes <<< cost of trouble required to install an electric a/c compressor

i'd say remote start is the way to go

6/25/2007 12:53:48 PM

i'm also crazy and i like doing things the unconventional/insane way.

6/25/2007 12:57:18 PM

http://rides.webshots.com/album/359668089RqnLfa

6/25/2007 1:01:14 PM

^my brother is buying a trailer from that guy.

yeah, remote start has a few simple yet very effective built in theft preventions:

1. the vehicle doesn't have to be unlocked.

2. you have to have the key to turn the ignition on.

3. the car shuts off if the brake pedal is depressed.

6/25/2007 1:26:28 PM

i really like what that guy did.

6/25/2007 1:39:44 PM