Reply
Thread Tools Display Modes
#1
Old 11-14-2002, 09:23 PM
Guest
Join Date: Feb 2001
Location: Seattle
Posts: 2,270
Why don't cars have AC electric outlets?

I just got a new car that has everything you could want, but of course no household-type 110/220 volt alternating current outlet. I am always wanting to plug things into my car, and it got me wondering: howcome this isn't offered?

Of course I know car electric systems run on DC; that's why you can't just use an ordinary adapter and plug your appliances into the cigarette lighter. But converters are sold that will plug into your lighter, convert the DC to AC and give you a two-pronged socket. Why aren't these standard - or at least optional - on cars?

Is it just that nobody wants this except me, or is it that it's bad for the electrical system in the long run?
#2
Old 11-14-2002, 09:33 PM
Guest
Join Date: Aug 2002
Location: Evergreen Terrace
Posts: 2,479
I thought the main reason for using AC in households was to sustain the ampage across the huge distances that the power lines had to travel. Following this logic, maybe DC is used in cars because the circuit from the power source to the outlet is so short.
#3
Old 11-14-2002, 09:45 PM
BANNED
Join Date: Nov 2001
Posts: 2,394
If you really want 120 vac 60 cycles, get an inverter.

Outside RV's, there's not much call for them - what would you want to operate (while the car is running - turn off the engine, and your battery is going to be dead real quick)?
#4
Old 11-14-2002, 10:02 PM
Guest
Join Date: Mar 2002
Posts: 258
And, of course, some new cars have them. The Pontiac Vibe/Toyota Matrix, for example.
#5
Old 11-14-2002, 10:02 PM
Guest
Join Date: Jan 2001
Location: Gallatin, TN
Posts: 21,676
Ac outlets are slowly starting to appear in vehicles. I believe one of the Big Three is now offering a pickup and SUV with AC outlets built in. This is supposedly a popular option for building contractors.

As for why it's never been offered, that's a different issue. Car makers do some strange things. (See The Master's column on headlights, for example.) It could simply be that there hasn't been much of a demand for one, or it could be a technical problem. I've seen plans on how to convert your car's alternator to put out 120 V AC, but the problem was it didn't put any juice into running the car, so it drained your battery. One could slap a second alternator on the car, I suppose, but that's kind of complicated.

There's talk of putting AC outlets into cars when they switch over to 42 Volt systems, and I think that the current system they're using has a generator built into the flywheel.
__________________
***Don't ask me, I don't post here any more, and I'm probably not even reading this now.***
#6
Old 11-14-2002, 11:08 PM
Guest
Join Date: Mar 2002
Location: Sykesville, MD
Posts: 1,617
42 volts? Since when did they start thinking this? I want in on this action.
#7
Old 11-15-2002, 12:40 AM
Charter Member
Join Date: Dec 1999
Location: Woodhaven,Queens, NY
Posts: 5,351
Quote:
Outside RV's, there's not much call for them - what would you want to operate (while the car is running - turn off the engine, and your battery is going to be dead real quick)?
You must not have kids. I bought an inverter this summer, at the same time I bought the videocasette player/monitor that plugs into the cigarette lighter. My van has two of the lighter sockets- front and back. Plugged the monitor into one, the inverter into the other and the PS2 into the inverter. Best 8 hour car ride I ever took.
#8
Old 11-15-2002, 12:49 AM
Guest
Join Date: Jul 1999
Location: Taint of creation
Posts: 33,150
Mainly because until recently car electrical systems and their generators really weren't up to delivering the kind of power AC devices require. As car electical systems became more robust to meet onboard electronic requirements adding AC/DC inverter capability was less challenging.

Hybrid cars will start switching over to 42 (or similar) voltage systems in the next few years. For whatever EE reason it's more efficient than 12V for heavy loads.


Ford: Hybrid Engine Will Boost Explorer's Fuel Efficiency 42%

Quote:
An electrical boost for acceleration is Ford Motor Co.'s (F) approach to the hybrid vehicle designs being unveiled at the Detroit Auto Show.

Ford hopes to boost fuel efficiency of its Explorer sport utility vehicle by 42% in 2004, from the current 19 miles per gallon to 27 miles per gallon, according to the Tuesday New York Times.

The new device shuts down the gasoline engine when the vehicle stops, but restarts it when the driver touches the accelerator, the Times said. This instant restart will require an upgrade in the Explorer's electrical system to 42 volts from the current 12 volts. The higher voltage will also power other systems that allow air and gasoline to be mixed with greater precision, the paper said. Transport Topics
#9
Old 11-15-2002, 02:11 AM
BANNED
Join Date: Nov 2001
Posts: 2,394
Looks like Ford's been in the loco weed again...

The engine starts "instantly" when the accelerator is depressed? That would be impressive technology - and useful if/when driving across a desert - how would that work in city driving? (We really need a "bemused" smiley).
#10
Old 11-15-2002, 02:21 AM
Member
Join Date: Aug 1999
Location: Alabama
Posts: 13,960
Quote:
Originally posted by happyheathen
The engine starts "instantly" when the accelerator is depressed?
Since they call it a "hybrid," I'd guess that the electric motor propels the car until the engine is up and running. Some of the current hybrid cars already work that way. And hybrid cars tend to be better suited for city driving than highway, because the frequent acceleration/deceleration is not an efficient way to run an internal combustion engine. Electric motors have high torque at low RPMs.

Many city buses in Japan are labeled "no idle" and stop the engine while the bus is not moving (red lights and bus stops). I don't know if the engine shutoff is automatic, but the engine has to be started first before the bus can move. So I take it it's just a regular engine with a more durable starter motor and a heavy duty electrical system.
#11
Old 11-15-2002, 09:06 AM
Guest
Join Date: Mar 2000
Location: The Industrial NorthEast
Posts: 1,505
Quote:
Originally posted by happyheathen
Looks like Ford's been in the loco weed again...

The engine starts "instantly" when the accelerator is depressed? That would be impressive technology - and useful if/when driving across a desert - how would that work in city driving? (We really need a "bemused" smiley).
I know one of the things 'they' say is necessary for Hybrids to really take off is the consolidation of the alternator/starter into one very lightweight but powerful unit. This is what's supposedly required for instant-on engines (fast, heavy cranking action), although I am a little skeptical how well this will work after, say 6 hard years down the road.
Oddly, I haven't seen anything on using the Battery power to get the vehicle moving while the engine cranks up, but maybe I just wasn't looking in the right places...
#12
Old 11-15-2002, 09:37 AM
Guest
Join Date: Mar 2002
Posts: 258
The Honda Insight and Civic hybrids already have this feature. The engine shuts off after idling for a few seconds -- at stoplights, etc. It starts back up when the accelerator pedal is depressed. From Edmund's:
Quote:
Like the Insight, the Civic Hybrid uses an automatic idle stop feature to save gas. When the driver comes to a complete stop at a traffic light, for example, the engine shuts off. Obviously, this saves gas and cuts emissions. To remind the driver that the engine has shut off on purpose, and has not merely stalled, a light on the instrument panel blinks.

The first time the engine stopped on the test drive, it produced a slight panic sensation in us. The feel of a throbbing engine is so basic to the driving experience. But, as with the CVT, we quickly got used to this feature. It even seemed relaxing to be waiting at a light without holding back the engine as it impatiently idled. In fact, as we drove away from the press event in a Ford Focus, and the engine didn't shut off at a traffic light, it suddenly seemed wasteful.
#13
Old 11-15-2002, 09:46 AM
Guest
Join Date: Mar 2001
Location: Plano, TX USA
Posts: 662
Re: The new 42V system: There are many benefits by going to 42V. Some of them are:

Higher voltage means less current for the same wattage. So the wiring can be made thinner = saved weight & money.

With 42V electric power steering is possible, as well as waterpump, oil pump etc. These would then only run when needed instead of being a parasitic loss on the engine all the time.

42V system will start showing up on new cars very soon. GM is said to start switching over in 2004 or 2005.

/Markus
#14
Old 11-15-2002, 12:27 PM
Guest
Join Date: Mar 2002
Posts: 146
Why 42 V? 48 is used commonly in a lot of other electrical (DC/battery) systems. How did they pick 42? Also, 48's an integer multiple of 12, and 42 isn't, and multiples are often popular.
#15
Old 11-15-2002, 01:50 PM
Member
Join Date: Mar 2002
Posts: 626
It seems to me that a live 120V wire in an automobile would be a safety issue in the event of a collision. Not only would the driver/passengers in the vehicle be at risk if the wiring became exposed but, if rescue workers need to use a chainsaw or 'jaws of life' type device, there would be some risk of electrocution.

Secondly, for U.S. cars, Detroit might realize that Americans are driving idiots and would be tooling around with hair driers and George Foreman FatBuster grills going full bore.

Having said all that though, I bet the real reason is that no one ever asked for it before.
#16
Old 11-15-2002, 02:44 PM
Guest
Join Date: Aug 2000
Location: In bed with your mom!
Posts: 4,127
Quote:
It seems to me that a live 120V wire in an automobile would be a safety issue in the event of a collision. Not only would the driver/passengers in the vehicle be at risk if the wiring became exposed but, if rescue workers need to use a chainsaw or 'jaws of life' type device, there would be some risk of electrocution.
I'd bet that not to many cars are actually running when rescuers are cutting through it with saws... let alone in running condition. Either way, I don't think that would be much of a problem.

Quote:
Mainly because until recently car electrical systems and their generators really weren't up to delivering the kind of power AC devices require. As car electical systems became more robust to meet onboard electronic requirements adding AC/DC inverter capability was less challenging.
I don't think thats it. High amperage (80+) alternators have been for decades. Usually only the most basic, bare bones vehicles with no options had the smallest available ones.
#17
Old 11-15-2002, 03:06 PM
Charter Member
Join Date: Jun 2000
Location: St. Louis, MO 50mi. West
Posts: 4,453
Quote:
Originally posted by bobk2
Why 42 V? 48 is used commonly in a lot of other electrical (DC/battery) systems. How did they pick 42? Also, 48's an integer multiple of 12, and 42 isn't, and multiples are often popular.
Lead Acid cells produce a nominal 2 volts. 42 volts would require 21 cells.

A NiCad or NiMH cells produces 1.2 volts each. This technology would require 35 cells.
#18
Old 11-15-2002, 04:34 PM
Guest
Join Date: Apr 1999
Location: Ohio
Posts: 10,448
Quote:
Originally posted by zwede
Higher voltage means less current for the same wattage. So the wiring can be made thinner = saved weight & money./Markus
Yep, that’s the main reason. Also, switches and relays can be made cheaper since the contacts don’t have to carry as much current.
#19
Old 11-15-2002, 05:27 PM
Charter Member
Join Date: Oct 1999
Location: Sturgeon Bay, WI USA
Posts: 19,905
If a higher DC voltage for car electronics is so good, why stop at 42 volts? Why not 52? 62? Or, <gulp>, 120?

What made 42 the magic number? Wasn't the boost from 6 to 12 some decades ago made for the same reason? Why did they only go from 6 to 12?

You don't know how long I've been waiting to ask these questions!
#20
Old 11-15-2002, 05:43 PM
Charter Member
Join Date: Apr 2002
Location: California
Posts: 8,078
It's misleading to compare the 42 volt sysytem to a 12 volt battery. The current (heh!) car battery delivers 12 volts, but when the car is running, it runs at 14 volts. Similarly, the new sysytem runs at 42 volts, but includes a 36 volt battery.

http://canadiandriver.com/articles/jk/at_010515.htm
Quote:
The first and primary reason for switching to 42 volt electrical systems is reliability. Older readers or admirers of antique automobiles will remember the old 6-volt electrical systems that were common until the late 1950's. At that time, the auto manufacturers switched to 12-volt systems for better reliability with the increase in electrical equipment on the vehicles. Now, another large increase in electrical content and computers on automobiles is creating the push to 42 volts.

The first 42-volt systems will likely be a hybrid. Some of the vehicle will work on 12 volts while the computer systems work on 42 volts. The 42-volt system is actually based on a 36-volt battery, but it is called 42 volts because this is what it will operate at when the vehicle is running. This is much like today's systems, which operate at 14 volts but use a 12-volt battery.

Modules will convert the 42 volts of the charging system into 14 volts so the older technology components will be able to function. These modules may be centrally located, powering several 12-volt devices, but advances in electronics may allow each 12-volt appliance to have its own module. Regardless of the configuration, hybrid systems will be present for a few years.
#21
Old 11-15-2002, 06:15 PM
Guest
Join Date: Apr 1999
Location: Ohio
Posts: 10,448
Quote:
Originally posted by Musicat
If a higher DC voltage for car electronics is so good, why stop at 42 volts? Why not 52? 62? Or, <gulp>, 120?

What made 42 the magic number? Wasn't the boost from 6 to 12 some decades ago made for the same reason? Why did they only go from 6 to 12?
Not sure, but it probably has to do with two things:

Safety. I believe 40 V (or around there) is the “critical” voltage level when it comes to human safety, i.e. a voltage below 40 V is generally considered “safe.” Generally.

Battery manufacturability. The higher the (battery) voltage, the more difficult the battery is to manufacture.
#22
Old 11-15-2002, 07:58 PM
Charter Member
Join Date: Oct 1999
Location: Sturgeon Bay, WI USA
Posts: 19,905
Quote:
Originally posted by Crafter_Man
I believe 40 V (or around there) is the “critical” voltage level when it comes to human safety, i.e. a voltage below 40 V is generally considered “safe.” Generally.
T'ain't the voltage, m'friend, tis the current. Stand near a Van DeGraf generator and 100,000 volts will pass thru your body without harm. Very low amperage.

What's high voltage?
#23
Old 11-15-2002, 08:51 PM
Guest
Join Date: Feb 2001
Location: Seattle
Posts: 2,270
Great info here, thanks. I didn't know a couple of cars now had 'em.

I see Doreen is managing a monitor and a PS2 with no problems. What happens if you push the envelope and do have your George Foreman Grill, your hairdryer, your laser printer and your Hello Kitty ricemaker all going at once? Do you blow a fuse, cream your alternator, drain the battery, eject the warp core, or what?
#24
Old 11-19-2002, 06:36 PM
Guest
Join Date: Apr 1999
Location: Ohio
Posts: 10,448
Quote:
Originally posted by Musicat
T'ain't the voltage, m'friend, tis the current. Stand near a Van DeGraf generator and 100,000 volts will pass thru your body without harm. Very low amperage.

What's high voltage?
Sorry to resurrect this one.

Um, no, sorry, you’re incorrect. And we’ve discussed this countless times before.

If it were really just due to “current,” then a car battery would fry you when you placed your hands across the terminals. After all, a car battery can put out 500 amps, can’t it?

A Van DeGraf generator won’t fry you because you really don’t have 100,000 volts making low-resistance contact with your body.

Suffice to say, if you want to get zapped all you need is enough voltage across you body so that over 10 mA flows through your body. There is no “magic” voltage level this occurs at, since it depends on your body resistance. But direct skin contact over 48V is considered “risky territory.”
#25
Old 11-19-2002, 07:41 PM
Guest
Join Date: Jan 2001
Location: Gallatin, TN
Posts: 21,676
Quote:
Originally posted by masonite
Great info here, thanks. I didn't know a couple of cars now had 'em.

I see Doreen is managing a monitor and a PS2 with no problems. What happens if you push the envelope and do have your George Foreman Grill, your hairdryer, your laser printer and your Hello Kitty ricemaker all going at once? Do you blow a fuse, cream your alternator, drain the battery, eject the warp core, or what?
You'd blow a fuse. Depending upon how the car's wired up, you might blow a couple.
#26
Old 11-19-2002, 08:04 PM
Charter Member
Join Date: Aug 1999
Posts: 16,451
Quote:
Originally posted by Musicat
If a higher DC voltage for car electronics is so good, why stop at 42 volts? Why not 52? 62? Or, <gulp>, 120?

What made 42 the magic number? Wasn't the boost from 6 to 12 some decades ago made for the same reason? Why did they only go from 6 to 12?

You don't know how long I've been waiting to ask these questions!

An electrical cell full charged puts out 2.12V. To recharge it you have to overcome internal resistance of 0.2V So to fully recharge a 12V (6 cell battery) requires 6 * 2.32 = 13.92V rounded off in converstaion to 14V.
An 18 cell battery (36V) would have a charging current of 41.76V call it 42 for short.
I was told by one of the engineers for our company that the reson for 42 was that in Europe; voltages above 48 require special training and certification. The car makers did not want to have to retrain/certify all of the technicians.
#27
Old 11-20-2002, 12:32 PM
ftg ftg is online now
Guest
Join Date: Feb 2001
Location: Not the PNW :-(
Posts: 15,860
Umm, being grounded and then touching a Van DeGraf generator is very dangerous.

The demos you see of people touching them require that they stand on insulating plastic platforms and are ordered to be very careful not to touch anything else. In particular, they are not to step off the platform during the demo. (A major concern when they feel little sparks and might panic.) Also, the demos I have seen ask the "victim" to put their feet together hard to avoid inadvertent shocks leaping between the feet.
#28
Old 11-20-2002, 01:50 PM
Guest
Join Date: Apr 1999
Location: Ohio
Posts: 10,448
Quote:
Originally posted by ftg
Umm, being grounded and then touching a Van DeGraf generator is very dangerous.

The demos you see of people touching them require that they stand on insulating plastic platforms and are ordered to be very careful not to touch anything else. In particular, they are not to step off the platform during the demo. (A major concern when they feel little sparks and might panic.) Also, the demos I have seen ask the "victim" to put their feet together hard to avoid inadvertent shocks leaping between the feet.
Are you sure about that?

The tabletop VandeGraaff Generators I’m familiar with do not appear to be dangerous. After all, it’s just a belt and a few combs! And I believe the reason you’re asked to stand on an insulator is to maximize the effect.

Here’s more info on it:

http://amasci.com/emotor/safe.html

BTW: The author of that page is a frequent poster here. Perhaps he can chime in.
#29
Old 11-20-2002, 02:32 PM
Guest
Join Date: Aug 2001
Location: Dallas, TX
Posts: 1,325
Crafter_Man is quite correct.

The reason for standing on the insulating platform is to allow the charge to build up in you. It is quite save to be grounded and hang on to a VandeGraaff Generator. That would just hide all the interesting effects.
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 06:04 PM.

Copyright © 2017
Best Topics: abandoned boat laws pixie pit minimum salary required percocets high men stroking penis qc padma burnt orange cars rfd address simpsons dragons latino lady scoe 10x ingredients combat space suit smoke shop profits open freezers dental catch phrases ron white drinking wiggles papadum fresh mandarin oranges transition lenses costco victor tate svu undeclared cancelled adam hilliker sabrina lloyd numbers personal zeppelin gekijo metalliche hire screenwriter endothermic fire thief for hire ozymandias pronounce 1800gotjunk price list take 3 benadryl do not push you kiss by th book pay to the order of stamp difference between 5w 30 and 5w 20 oil how long does it take for piercings to heal how do you say i love you mom in spanish bag balm for hemorrhoids is there a difference between 123 and 123a batteries what happens if you give the right address but wrong zip code why does pus smell how deep does a power pole go origin of row row row your boat brass and galvanized pipe corrosion ruth chris aruba dress code can t sleep on back convert 220 outlet to 110 how do you pronounce koch turned on a dime no one likes me everybody hates me lyrics a&r man how to spread butter counting coins by weight yogi bear vs yogi berra name a popular movie trilogy family feud english muffins in england convert rpm to mph stationary bike hyphenated last names alphabetical order is there a drano for toilets car on the side of the road sawdust on the floor dinosaur books for adults what does aggro mean rubber biscuit the chips watery diarrhea every 20 minutes how long do countries last