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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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48 volt car elect not going to happen
The high(er) voltage car electrical system is not going to happen anytime
soon. The reasons, according to an article in Car and Driver are a) reliable circuit protection hasn't been developed to the point where manufacturers are 100% sure a loose wire or a short won't result in a shock or fire and b) 12 volts is an ideal voltage for headlight filaments- higher voltages mandate thinner filaments which don't survive bumps and bangs very well. Apparently GM was going to 48 volts for the 2006 model year, but backed off mostly because of the circuit protection issue. -Carl |
#2
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48 volt car elect not going to happen
"Carl Byrns" wrote in message news:5l5pj.41034$K%.16220@trnddc04... The high(er) voltage car electrical system is not going to happen anytime soon. The reasons, according to an article in Car and Driver are a) reliable circuit protection hasn't been developed to the point where manufacturers are 100% sure a loose wire or a short won't result in a shock or fire and That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. Would the advantages of higher voltage systems be worth that result? Vaughn |
#3
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48 volt car elect not going to happen
On Feb 2, 3:35 pm, "Vaughn Simon"
wrote: "Carl Byrns" wrote in message news:5l5pj.41034$K%.16220@trnddc04... The high(er) voltage car electrical system is not going to happen anytime soon. The reasons, according to an article in Car and Driver are a) reliable circuit protection hasn't been developed to the point where manufacturers are 100% sure a loose wire or a short won't result in a shock or fire and That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. Would the advantages of higher voltage systems be worth that result? Vaughn So, what voltage do the hybrid vehicles run at? I thought is was over 100, possibly 200 volts. Paul |
#4
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48 volt car elect not going to happen
So, what voltage do the hybrid vehicles run at? I thought is was over 100, possibly 200 volts. Yes, but that is "apples and oranges". (correct me if I am wrong) In a hybrid car, most of the electrics are still 12 volt, the high voltage battery just runs the hybrid part, and those wires are made very obvious. The original post was about the potential conversion of ALL the electrics in conventional cars to 48 volts. Vaughn |
#5
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48 volt car elect not going to happen
On 2008-02-03, Vaughn Simon wrote:
So, what voltage do the hybrid vehicles run at? I thought is was over 100, possibly 200 volts. Yes, but that is "apples and oranges". (correct me if I am wrong) In a hybrid car, most of the electrics are still 12 volt, the high voltage battery just runs the hybrid part, and those wires are made very obvious. So, in an electric car, the starter is 12 volts? i |
#6
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48 volt car elect not going to happen
On Sat, 02 Feb 2008 20:34:00 -0600, with neither quill nor qualm,
Ignoramus17662 quickly quoth: On 2008-02-03, Vaughn Simon wrote: So, what voltage do the hybrid vehicles run at? I thought is was over 100, possibly 200 volts. Yes, but that is "apples and oranges". (correct me if I am wrong) In a hybrid car, most of the electrics are still 12 volt, the high voltage battery just runs the hybrid part, and those wires are made very obvious. So, in an electric car, the starter is 12 volts? I wonder how many cheeks you'll catch with that big hook, Ig. --- The world is wide, and I will not waste my life in friction when it could be turned into momentum. --Frances Willard (1839 - 1898) ---------- |
#7
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48 volt car elect not going to happen
On 2008-02-03, Larry Jaques novalidaddress@di wrote:
On Sat, 02 Feb 2008 20:34:00 -0600, with neither quill nor qualm, Ignoramus17662 quickly quoth: On 2008-02-03, Vaughn Simon wrote: So, what voltage do the hybrid vehicles run at? I thought is was over 100, possibly 200 volts. Yes, but that is "apples and oranges". (correct me if I am wrong) In a hybrid car, most of the electrics are still 12 volt, the high voltage battery just runs the hybrid part, and those wires are made very obvious. So, in an electric car, the starter is 12 volts? I wonder how many cheeks you'll catch with that big hook, Ig. None so far, but I am waiting... i The world is wide, and I will not waste my life in friction when it could be turned into momentum. |
#8
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48 volt car elect not going to happen
On Feb 2, 2:33�pm, "Carl Byrns" wrote:
Apparently GM was going to 48 volts for the 2006 model year, but backed off mostly because of the circuit protection issue. -Carl Carl et all The 48 volt figure is the nominal battery voltage, 4 X 12, closest to 52 volts which is the nominal voltage at which one gets shocked. IOW the maximun safe voltage to work with before the voltage becomes a shock hazard. There are of course exceptions to this. The kickback from an inductance load can be many times the 12 volts that we presently are accostomed to working with. Also the 48 volt figure is not the maximun charging voltage when charging a 48 volt system. eg the charging voltage for a 12 volt system is 13.5 to 14.X something. I read all this stuff perhaps 20 years ago when talk of higher voltage Automobile Electric Systems was started. I don't remember the source of the documentation. Probably a government publication. Bob AZ |
#9
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48 volt car elect not going to happen
That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. How will 48v kill people, except for causing a fire, which 12 v is quite capable of doing that also. |
#10
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48 volt car elect not going to happen
On 2008-02-03, Bob AZ wrote:
The 48 volt figure is the nominal battery voltage, 4 X 12, closest to 52 volts which is the nominal voltage at which one gets shocked. IOW the maximun safe voltage to work with before the voltage becomes a shock hazard. There are of course exceptions to this. The kickback from an inductance load can be many times the 12 volts that we presently are accostomed to working with. Also the 48 volt figure is not the maximun charging voltage when charging a 48 volt system. eg the charging voltage for a 12 volt system is 13.5 to 14.X something. I read all this stuff perhaps 20 years ago when talk of higher voltage Automobile Electric Systems was started. I don't remember the source of the documentation. Probably a government publication. Why are they not considering lower voltages, such as 24 nominal, which is used in commercial trucks? i |
#11
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48 volt car elect not going to happen
On Sat, 02 Feb 2008 20:34:00 -0600, Ignoramus17662 wrote:
On 2008-02-03, Vaughn Simon wrote: So, what voltage do the hybrid vehicles run at? I thought is was over 100, possibly 200 volts. Yes, but that is "apples and oranges". (correct me if I am wrong) In a hybrid car, most of the electrics are still 12 volt, the high voltage battery just runs the hybrid part, and those wires are made very obvious. So, in an electric car, the starter is 12 volts? i I thought the electric cars were hand-cranked. -- Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html |
#12
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48 volt car elect not going to happen
"Stephen Robinson" wrote in message ... That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. How will 48v kill people, except for causing a fire, which 12 v is quite capable of doing that also. Do you own an arc welder? Look at the open circuit voltage(should be on the case somewhere). Now look at all the shock hazard warnings. If you don't own an arc welder the open circuit voltage is usually around 48 volts and arc voltage is around 25 volts (sound familiar?) and at the right amperage that is enough to kill you. -Carl |
#13
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48 volt car elect not going to happen
"Stephen Robinson" wrote: You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. ^^^^^^^^^^^^^^^^^^^^^^^ It is refreshing that SOMEONE seems to know this. However, I have a couple of reservations about your second sentence. The resistance of the body is almost entirely in the skin, which is quite high when dry. If, somehow, you got across some voltage while wet, or perhaps bleeding from an accident, the resistance could be very much lower. Secondly, the amount of current that can be lethal depends on the path through the body. The worst would be across the shoulders, which places the heart in the circuit. The path from one hand to the other, or from one hand to some lower part of the body could also be quite dangerous. |
#14
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48 volt car elect not going to happen
On 2008-02-03, Stephen Robinson wrote:
Carl Byrns wrote: "Stephen Robinson" wrote in message ... That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. How will 48v kill people, except for causing a fire, which 12 v is quite capable of doing that also. Do you own an arc welder? Look at the open circuit voltage(should be on the case somewhere). Now look at all the shock hazard warnings. If you don't own an arc welder the open circuit voltage is usually around 48 volts and arc voltage is around 25 volts (sound familiar?) and at the right amperage that is enough to kill you. -Carl You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. Not the case if a wet human body is holding on to car frame, while grabbing firmly some unlucky item energized to 48 volts. Resistance depends mostly on how contact is done. |
#15
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48 volt car elect not going to happen
Carl Byrns wrote:
"Stephen Robinson" wrote in message ... That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. How will 48v kill people, except for causing a fire, which 12 v is quite capable of doing that also. Do you own an arc welder? Look at the open circuit voltage(should be on the case somewhere). Now look at all the shock hazard warnings. If you don't own an arc welder the open circuit voltage is usually around 48 volts and arc voltage is around 25 volts (sound familiar?) and at the right amperage that is enough to kill you. -Carl You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. |
#16
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48 volt car elect not going to happen
Leo Lichtman wrote:
"Stephen Robinson" wrote: You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. ^^^^^^^^^^^^^^^^^^^^^^^ It is refreshing that SOMEONE seems to know this. However, I have a couple of reservations about your second sentence. The resistance of the body is almost entirely in the skin, which is quite high when dry. If, somehow, you got across some voltage while wet, or perhaps bleeding from an accident, the resistance could be very much lower. Secondly, the amount of current that can be lethal depends on the path through the body. The worst would be across the shoulders, which places the heart in the circuit. The path from one hand to the other, or from one hand to some lower part of the body could also be quite dangerous. Agreed, I still don't think 48 v is going to be very dangerous. |
#17
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48 volt car elect not going to happen
On Sun, 03 Feb 2008 05:26:20 GMT, "Carl Byrns"
wrote: "Stephen Robinson" wrote in message ... That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. How will 48v kill people, except for causing a fire, which 12 v is quite capable of doing that also. Do you own an arc welder? Look at the open circuit voltage(should be on the case somewhere). Now look at all the shock hazard warnings. If you don't own an arc welder the open circuit voltage is usually around 48 volts and arc voltage is around 25 volts (sound familiar?) and at the right amperage that is enough to kill you. -Carl The user handholds the live stinger of an arcwelder. BTW, the O.C.V on many arcwelders is more like 60 to 80 volts. Your house is wired with 110 volts, except for stove, dryer, A/C and perhaps some stuff in the shop which is 220V hot-to-hot. In Europe all domestic sockets are 240V. The issue is cost of change. Some NEC wiring codes kick in at (I think) around 48 volts so 36/42 volts sounds good for automotive. Insulation is considerably cheaper and lighter than copper. Another cost issue is switching and fault management of DC, which tends to hold an arc at higher voltages. Fuses and contacts don't break higher-voltage DC current well unless specifically designed to do that. There's also the issue of the lightbulb mfrs worrying about cost of moving to thinner, longer more fragile filaments. These issues can and will be solved, eventually if not sooner. Silicon in high volume keeps getting cheaper and more capable. When the cost of not changing becomes higher to the mfr than cost of change, then change will happen. |
#18
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48 volt car elect not going to happen
On Feb 3, 1:25 am, Don Foreman wrote:
On Sun, 03 Feb 2008 05:26:20 GMT, "Carl Byrns" wrote: "Stephen Robinson" wrote in message ... That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. How will 48v kill people, except for causing a fire, which 12 v is quite capable of doing that also. Do you own an arc welder? Look at the open circuit voltage(should be on the case somewhere). Now look at all the shock hazard warnings. If you don't own an arc welder the open circuit voltage is usually around 48 volts and arc voltage is around 25 volts (sound familiar?) and at the right amperage that is enough to kill you. -Carl The user handholds the live stinger of an arcwelder. BTW, the O.C.V on many arcwelders is more like 60 to 80 volts. Your house is wired with 110 volts, except for stove, dryer, A/C and perhaps some stuff in the shop which is 220V hot-to-hot. In Europe all domestic sockets are 240V. The issue is cost of change. Some NEC wiring codes kick in at (I think) around 48 volts so 36/42 volts sounds good for automotive. Insulation is considerably cheaper and lighter than copper. Another cost issue is switching and fault management of DC, which tends to hold an arc at higher voltages. Fuses and contacts don't break higher-voltage DC current well unless specifically designed to do that. There's also the issue of the lightbulb mfrs worrying about cost of moving to thinner, longer more fragile filaments. These issues can and will be solved, eventually if not sooner. Silicon in high volume keeps getting cheaper and more capable. When the cost of not changing becomes higher to the mfr than cost of change, then change will happen. The trip time of a "fast blow" MIL STD circuit breaker at 1000% over current is specified around 880 milliseconds. You have to design the current path for what may be a very low operating current for fault current. Going from 12 v to 48 v will quadruple the fault current keeping everything else the same (it's only the source and wire resistance that limits this). When you use circuit boards to carry this current, the circuit trace has to support this current until the circuit breaker trips. Empirically we figured this to be 25AWG of copper for a 28 volt aircraft DC system. What's interesting is if the circuit trace "pops", the circuit breaker never does, and FR4 (fire retardant PWB material) converts to carbon from this, and since ground planes are used, this burnt trace makes a connection to ground. The leakage current starts the board to glow orange where this occurs, and emit smoke, and it burns like a firecracker fuse until all the board carbon is converted to ash. The circuit breaker never trips as this current is well under the 2-10 amp ratings. ignator |
#19
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48 volt car elect not going to happen
"Stephen Robinson" wrote in message ... Leo Lichtman wrote: "Stephen Robinson" wrote: You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. ^^^^^^^^^^^^^^^^^^^^^^^ It is refreshing that SOMEONE seems to know this. However, I have a couple of reservations about your second sentence. The resistance of the body is almost entirely in the skin, which is quite high when dry. If, somehow, you got across some voltage while wet, or perhaps bleeding from an accident, the resistance could be very much lower. Secondly, the amount of current that can be lethal depends on the path through the body. The worst would be across the shoulders, which places the heart in the circuit. The path from one hand to the other, or from one hand to some lower part of the body could also be quite dangerous. Agreed, I still don't think 48 v is going to be very dangerous. 48 volts DC is not very dangerous. But because of the conditions car mechanics work under, especially backyard mechanics, it could be contribute to a more dangerous situation. I think we'll see a lot more off the cuff "arc welding" of Craftsman adjustable wrenches. |
#20
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48 volt car elect not going to happen
"Don Foreman" wrote in message ... On Sun, 03 Feb 2008 05:26:20 GMT, "Carl Byrns" wrote: "Stephen Robinson" wrote in message ... That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. How will 48v kill people, except for causing a fire, which 12 v is quite capable of doing that also. Do you own an arc welder? Look at the open circuit voltage(should be on the case somewhere). Now look at all the shock hazard warnings. If you don't own an arc welder the open circuit voltage is usually around 48 volts and arc voltage is around 25 volts (sound familiar?) and at the right amperage that is enough to kill you. -Carl The user handholds the live stinger of an arcwelder. BTW, the O.C.V on many arcwelders is more like 60 to 80 volts. Not mine ( I checked) 48 and 25 are the numbers. The stinger _is_ insulated, no? -Carl |
#21
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48 volt car elect not going to happen
"Stephen Robinson" wrote in message ... You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. I'll let you test that theory g. In the mean time, you might want to read sk's post on aircraft (24v) circuits. -Carl |
#22
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48 volt car elect not going to happen
On Sun, 03 Feb 2008 01:25:36 -0600, with neither quill nor qualm, Don
Foreman quickly quoth: The user handholds the live stinger of an arcwelder. BTW, the O.C.V on many arcwelders is more like 60 to 80 volts. Your house is wired with 110 volts, except for stove, dryer, A/C and perhaps some stuff in the shop which is 220V hot-to-hot. In Europe all domestic sockets are 240V. In many instances, contact with 240v will give you a quicker jolt so you're more likely to jump away from contact with it. I know the difference in feel and have worked with live circuits more often than not. Nitrile gloves are good insulators, so pokes through them by the wire ends let you know it's still hot. g The issue is cost of change. Some NEC wiring codes kick in at (I think) around 48 volts so 36/42 volts sounds good for automotive. Insulation is considerably cheaper and lighter than copper. Another cost issue is switching and fault management of DC, which tends to hold an arc at higher voltages. Fuses and contacts don't break higher-voltage DC current well unless specifically designed to do that. Yeah, arcing is bad news for switches. What's the voltage level at which capacitors start helping with that, I wonder? I know they're much more active on AC circuits. There's also the issue of the lightbulb mfrs worrying about cost of moving to thinner, longer more fragile filaments. But with the trend toward all LED lighting, what's the worry? Very few bulbs remain, such as headlamps, and those could be regulated or transformed down to 12v pretty cheaply. These issues can and will be solved, eventually if not sooner. Silicon in high volume keeps getting cheaper and more capable. When the cost of not changing becomes higher to the mfr than cost of change, then change will happen. -- I think this is the crux of the global warming media hype (not some of the science). Gobal warming research and it's ugly step-sister, the media, are a business. They will only feed frenzy that adds to their business. Hence, the lack of talk about your cold and snowy western weather, lack of hurricanes in '06, etc. The only things that will be brought up are those that will "help" their cause and industry. Do something for something we KNOW about, like the kid down the street that needs a home, etc. Don't try to help for something that we are trying (ridiculously) to predict will be a problem 100-200years from now!! Thanks, A Liberal, Environmentally Friendly, Global Warming, Anti-Hype Lad James, 11Jan07 on Weather Channel's "One Degree" hype site |
#23
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48 volt car elect not going to happen
On Sun, 03 Feb 2008 13:32:48 GMT, with neither quill nor qualm, "Carl
Byrns" quickly quoth: "Don Foreman" wrote in message .. . The user handholds the live stinger of an arcwelder. BTW, the O.C.V on many arcwelders is more like 60 to 80 volts. Not mine ( I checked) 48 and 25 are the numbers. The stinger _is_ insulated, no? As are welding rods, and anyone above a halfwit wears gloves when welding. Well, 'cept those in 3rd world countries using live 240v 3-phase xfmrs without goggles, long-sleeved pants, gloves, shoes, or shirt. Remember that picture a few months ago? g -- I think this is the crux of the global warming media hype (not some of the science). Gobal warming research and it's ugly step-sister, the media, are a business. They will only feed frenzy that adds to their business. Hence, the lack of talk about your cold and snowy western weather, lack of hurricanes in '06, etc. The only things that will be brought up are those that will "help" their cause and industry. Do something for something we KNOW about, like the kid down the street that needs a home, etc. Don't try to help for something that we are trying (ridiculously) to predict will be a problem 100-200years from now!! Thanks, A Liberal, Environmentally Friendly, Global Warming, Anti-Hype Lad James, 11Jan07 on Weather Channel's "One Degree" hype site |
#24
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48 volt car elect not going to happen
Ignoramus17662 wrote:
On 2008-02-03, Vaughn Simon wrote: So, what voltage do the hybrid vehicles run at? I thought is was over 100, possibly 200 volts. Yes, but that is "apples and oranges". (correct me if I am wrong) In a hybrid car, most of the electrics are still 12 volt, the high voltage battery just runs the hybrid part, and those wires are made very obvious. So, in an electric car, the starter is 12 volts? i We have a Honda Civic Hybrid and, best I can tell, the starter IS 12 volts, and is operated from the 12v battery. The kicker is that engine always starts with the assist motor, which operates off the 156v battery. The engine starts silently, I've never heard the starter operate. I believe that the starter is for emergency use, that is, when the assist system is not working. Note that this system is quite a bit different from the Prelude. -- Gary Brady Austin, TX www.powdercoatoven.4t.com |
#25
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48 volt car elect not going to happen
In article 5l5pj.41034$K%.16220@trnddc04, "Carl Byrns"
wrote: The high(er) voltage car electrical system is not going to happen anytime soon. ....SNIP... Shucks, I'm sure going to miss that promised steering-wheel heater in my next SUV. grin -- Paul S. Remove Before Flight |
#26
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48 volt car elect not going to happen
On Feb 3, 12:09 am, "Leo Lichtman"
wrote: "Stephen Robinson" wrote: You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. ^^^^^^^^^^^^^^^^^^^^^^^ It is refreshing that SOMEONE seems to know this. However, I have a couple of reservations about your second sentence. The resistance of the body is almost entirely in the skin, which is quite high when dry. If, somehow, you got across some voltage while wet, or perhaps bleeding from an accident, the resistance could be very much lower. Secondly, the amount of current that can be lethal depends on the path through the body. The worst would be across the shoulders, which places the heart in the circuit. The path from one hand to the other, or from one hand to some lower part of the body could also be quite dangerous. Or, if the electrode you touch happens to have a sharp point or edge. |
#27
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48 volt car elect not going to happen
"Leo Lichtman" wrote in message ... "Stephen Robinson" wrote: You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. ^^^^^^^^^^^^^^^^^^^^^^^ It is refreshing that SOMEONE seems to know this. Apparently none of those people work at GM (the focus of the article). GM backed off of 48 volts because of the reasons listed in the article, one of which was shock hazard. -Carl |
#28
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48 volt car elect not going to happen
"Stephen Robinson" wrote: You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. ^^^^^^^^^^^^^^^^^^^^^^^ It is refreshing that SOMEONE seems to know this. However, I have a couple of reservations about your second sentence. The resistance of the body is almost entirely in the skin, which is quite high when dry. If, somehow, you got across some voltage while wet, or perhaps bleeding from an accident, the resistance could be very much lower. Secondly, the amount of current that can be lethal depends on the path through the body. The worst would be across the shoulders, which places the heart in the circuit. The path from one hand to the other, or from one hand to some lower part of the body could also be quite dangerous. I worked for the local cable company for over 18 years.... and at that time, the plant was powered with 60Volt AC. We did all the splicing, coring of the cable, etc., while AC was on and occasionally would get a bite. Worst was while it was raining and everything was wet.... however, I understand the entire system is now powered with 90 Volt AC. We never died..... Ken. |
#29
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48 volt car elect not going to happen
Gary Brady wrote:
We have a Honda Civic Hybrid and, best I can tell, the starter IS 12 volts, and is operated from the 12v battery. The kicker is that engine always starts with the assist motor, which operates off the 156v battery. The engine starts silently, I've never heard the starter operate. I believe that the starter is for emergency use, that is, when the assist system is not working. Or when you can't afford replacing drive batteries late in vehicles life cycle? At least they were thinking. Wes |
#30
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48 volt car elect not going to happen
"Leo Lichtman" wrote:
"Stephen Robinson" wrote: You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. ^^^^^^^^^^^^^^^^^^^^^^^ It is refreshing that SOMEONE seems to know this. However, I have a couple of reservations about your second sentence. The resistance of the body is almost entirely in the skin, which is quite high when dry. If, somehow, you got across some voltage while wet, or perhaps bleeding from an accident, the resistance could be very much lower. Secondly, the amount of current that can be lethal depends on the path through the body. The worst would be across the shoulders, which places the heart in the circuit. The path from one hand to the other, or from one hand to some lower part of the body could also be quite dangerous. The worst burn I ever got was from a Honeywell Strobonar battery pack for a flash unit. A huge 9.6 volts iirc. Unfortuantly, I had traces of photodeveloping chemicals on my hands and the salts made my palm, in contact with the power contacts very conductive. Instant steam burn. OUCH! Wes |
#31
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48 volt car elect not going to happen
"Carl Byrns" wrote:
I'll let you test that theory g. In the mean time, you might want to read sk's post on aircraft (24v) circuits. 24v bites too. I used to be a Phantom Phixer. F4-J / F4-S Wes |
#32
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48 volt car elect not going to happen
Ken Sterling (Ken Sterling) wrote in message ... I worked for the local cable company for over 18 years.... and at that time, the plant was powered with 60Volt AC. We did all the splicing, coring of the cable, etc., while AC was on and occasionally would get a bite. Worst was while it was raining and everything was wet.... however, I understand the entire system is now powered with 90 Volt AC. We never died..... As an electrician, I have been zapped by 120 VAC and even 220 VAC more times than I would like to admit. Fortunately, I am still alive. Unfortunately, that does nothing to prove that shocks from 120 VAC and 220 VAC are not sometimes lethal. Vaughn |
#33
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48 volt car elect not going to happen
On Sun, 03 Feb 2008 14:53:56 -0500, with neither quill nor qualm, Wes
quickly quoth: "Carl Byrns" wrote: I'll let you test that theory g. In the mean time, you might want to read sk's post on aircraft (24v) circuits. 24v bites too. I used to be a Phantom Phixer. F4-J / F4-S So do fans and fan belts (and lathes, mills, saws, & grinders), but you're careful when working around them, right? "WTF is the difference?" he queried, innocently. -- I think this is the crux of the global warming media hype (not some of the science). Gobal warming research and it's ugly step-sister, the media, are a business. They will only feed frenzy that adds to their business. Hence, the lack of talk about your cold and snowy western weather, lack of hurricanes in '06, etc. The only things that will be brought up are those that will "help" their cause and industry. Do something for something we KNOW about, like the kid down the street that needs a home, etc. Don't try to help for something that we are trying (ridiculously) to predict will be a problem 100-200years from now!! Thanks, A Liberal, Environmentally Friendly, Global Warming, Anti-Hype Lad James, 11Jan07 on Weather Channel's "One Degree" hype site |
#34
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48 volt car elect not going to happen
Carl Byrns wrote:
The high(er) voltage car electrical system is not going to happen anytime soon. The reasons, according to an article in Car and Driver are a) reliable circuit protection hasn't been developed to the point where manufacturers are 100% sure a loose wire or a short won't result in a shock or fire and b) 12 volts is an ideal voltage for headlight filaments- higher voltages mandate thinner filaments which don't survive bumps and bangs very well. Apparently GM was going to 48 volts for the 2006 model year, but backed off mostly because of the circuit protection issue. So sorry you are so far behind the times. The Prius has had a 300 V DC supply for about 9 (?) years, now. There are several us-label cars with 42 V systems for their start/stop engines. Cars with 12 V systems DEFINITELY have a history of electrical fires, although they are fairly rare. I've seen one, but it had a bunch of ham gear in it, so it was likely modifications not the stock hardware that caused it. I think a number of these systems have a small auxilliary battery for the 12 V systems, so that that supply remains available after a failure or accident trips the intertial cutoff switch. Jon |
#35
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48 volt car elect not going to happen
Ignoramus17662 wrote:
On 2008-02-03, Vaughn Simon wrote: So, what voltage do the hybrid vehicles run at? I thought is was over 100, possibly 200 volts. Yes, but that is "apples and oranges". (correct me if I am wrong) In a hybrid car, most of the electrics are still 12 volt, the high voltage battery just runs the hybrid part, and those wires are made very obvious. So, in an electric car, the starter is 12 volts? i The Prius starts with the same motors as the traction system, so it is 300 V. They have a really UNIQUE system with two motors running on VFDs, connected by planetary gears with the engine. So, they run power from one motor to the other through the VFDs to perform the task of a transmission. The air conditioning compressor is run by a smaller motor and VFD. Jon |
#36
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48 volt car elect not going to happen
Stephen Robinson wrote:
You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. Unless your hands are wet, or maybe your skin is pierced by a few frayed strands of the wires. That really lowers your resistance. Jon |
#37
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48 volt car elect not going to happen
Leo Lichtman wrote:
"Stephen Robinson" wrote: You need the VOLTAGE to to push the CURRENT in order to kill someone(approx 30 mA).The human body is a very high resistance object, which needs very high voltage to provide that current. 48v ain't gonna be enough. ^^^^^^^^^^^^^^^^^^^^^^^ It is refreshing that SOMEONE seems to know this. However, I have a couple of reservations about your second sentence. The resistance of the body is almost entirely in the skin, which is quite high when dry. If, somehow, you got across some voltage while wet, or perhaps bleeding from an accident, the resistance could be very much lower. Secondly, the amount of current that can be lethal depends on the path through the body. The worst would be across the shoulders, which places the heart in the circuit. The path from one hand to the other, or from one hand to some lower part of the body could also be quite dangerous. Actually either arm to the opposite leg is supposed to be the worst. I've gotten some shocks that get into the letal level, but it just happened to hit my muscles in the way that threw me off the circuit instead of the opposite. The worst is the condition of being "tetanized" where your muscles lock you on the circuit, and it can actually be very hard for insulated persons to knok you free with a hot stick or similar tool. One guy at work was using a bad hot stick, and got tetanized while flipping a 4160 V switch and his safety watcher had to beat the CRAP out of him to break the connection. (I don't work on this high tension stuff, but electronics, but I am aware of the hazards.) Jon |
#38
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48 volt car elect not going to happen
In article
, "Vaughn Simon" wrote: Ken Sterling (Ken Sterling) wrote in message ... I worked for the local cable company for over 18 years.... and at that time, the plant was powered with 60Volt AC. We did all the splicing, coring of the cable, etc., while AC was on and occasionally would get a bite. Worst was while it was raining and everything was wet.... however, I understand the entire system is now powered with 90 Volt AC. We never died..... As an electrician, I have been zapped by 120 VAC and even 220 VAC more times than I would like to admit. Fortunately, I am still alive. Unfortunately, that does nothing to prove that shocks from 120 VAC and 220 VAC are not sometimes lethal. I've been zapped with 250,000 volts and lived (low current Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/ |
#39
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48 volt car elect not going to happen
On Sun, 3 Feb 2008 02:00:34 -0800 (PST), sk
wrote: On Feb 3, 1:25 am, Don Foreman wrote: On Sun, 03 Feb 2008 05:26:20 GMT, "Carl Byrns" wrote: "Stephen Robinson" wrote in message ... That suits me. Under the right conditions, 48 volts is plenty enough to kill. Therefore, one inevitable result of 48 volt electrical systems in cars will be the occasional dead mechanic. How will 48v kill people, except for causing a fire, which 12 v is quite capable of doing that also. Do you own an arc welder? Look at the open circuit voltage(should be on the case somewhere). Now look at all the shock hazard warnings. If you don't own an arc welder the open circuit voltage is usually around 48 volts and arc voltage is around 25 volts (sound familiar?) and at the right amperage that is enough to kill you. -Carl The user handholds the live stinger of an arcwelder. BTW, the O.C.V on many arcwelders is more like 60 to 80 volts. Your house is wired with 110 volts, except for stove, dryer, A/C and perhaps some stuff in the shop which is 220V hot-to-hot. In Europe all domestic sockets are 240V. The issue is cost of change. Some NEC wiring codes kick in at (I think) around 48 volts so 36/42 volts sounds good for automotive. Insulation is considerably cheaper and lighter than copper. Another cost issue is switching and fault management of DC, which tends to hold an arc at higher voltages. Fuses and contacts don't break higher-voltage DC current well unless specifically designed to do that. There's also the issue of the lightbulb mfrs worrying about cost of moving to thinner, longer more fragile filaments. These issues can and will be solved, eventually if not sooner. Silicon in high volume keeps getting cheaper and more capable. When the cost of not changing becomes higher to the mfr than cost of change, then change will happen. The trip time of a "fast blow" MIL STD circuit breaker at 1000% over current is specified around 880 milliseconds. You have to design the current path for what may be a very low operating current for fault current. Going from 12 v to 48 v will quadruple the fault current keeping everything else the same (it's only the source and wire resistance that limits this). When you use circuit boards to carry this current, the circuit trace has to support this current until the circuit breaker trips. Empirically we figured this to be 25AWG of copper for a 28 volt aircraft DC system. What's interesting is if the circuit trace "pops", the circuit breaker never does, and FR4 (fire retardant PWB material) converts to carbon from this, and since ground planes are used, this burnt trace makes a connection to ground. The leakage current starts the board to glow orange where this occurs, and emit smoke, and it burns like a firecracker fuse until all the board carbon is converted to ash. The circuit breaker never trips as this current is well under the 2-10 amp ratings. ignator I don't minimize the issues. I merely think that if existing solutions don't suffice, better solutions will be found if/when motivation is sufficient to develop them. |
#40
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48 volt car elect not going to happen
On Sun, 03 Feb 2008 15:41:11 -0600, with neither quill nor qualm, nick
hull quickly quoth: In article , "Vaughn Simon" wrote: Ken Sterling (Ken Sterling) wrote in message ... I worked for the local cable company for over 18 years.... and at that time, the plant was powered with 60Volt AC. We did all the splicing, coring of the cable, etc., while AC was on and occasionally would get a bite. Worst was while it was raining and everything was wet.... however, I understand the entire system is now powered with 90 Volt AC. We never died..... As an electrician, I have been zapped by 120 VAC and even 220 VAC more times than I would like to admit. Fortunately, I am still alive. Unfortunately, that does nothing to prove that shocks from 120 VAC and 220 VAC are not sometimes lethal. I've been zapped with 250,000 volts and lived (low current Were you on all fours and running with the rest of the herd at the time? gd&r -- Our greatest glory is not in never falling, but in getting up every time we do. -- Confucius |
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