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12V car cig lighter adapters - safe?
My family have a fair number of electrical devices ranging from mobile
phones to electronic games to fridges, all of which lend themselves to being able to be powered or charged on the road by a 12V cigarette lighter adapter. My question is, how safe are these adapters in terms of risking possible damage to the device in question? I read about 'surges' in power from the car; if so, is it down to circuitry built in to the device in question to protect itself from that? Or should such protection be built into the actual adapter? Is it risky to buy a 'cheapo' aftermarket adapter in place of the device manufacturer - might that be a more dangerous proposition than buying an 'original' item? If so, how can you tell what's safe, other than by spending as much cash as possible? Can an existing adapter be tested for this? Thanks David |
12V car cig lighter adapters - safe?
Graham wrote:
"Lobster" wrote in message ... My family have a fair number of electrical devices ranging from mobile phones to electronic games to fridges, all of which lend themselves to being able to be powered or charged on the road by a 12V cigarette lighter adapter. My question is, how safe are these adapters in terms of risking possible damage to the device in question? I've never had any problem with damage to delicate equipment like phones or satnav. Its a wise precaution to connect the ciggy plug before connecting the equipment just incase the power goes on and off a few times as you plug it in, but I've never had any problem. I read about 'surges' in power from the car; if so, is it down to circuitry built in to the device in question to protect itself from that? Or should such protection be built into the actual adapter? Varies. Some adaptor leads have a regulator inside to bring voltage down to what the equipment needs and this will give protection, but from what? Alternator going overvolts will be sunk into the battery, so impossible to go above the battery terminal voltage. Is it risky to buy a 'cheapo' aftermarket adapter in place of the device manufacturer - might that be a more dangerous proposition than buying an 'original' item? If so, how can you tell what's safe, other than by spending as much cash as possible? Can an existing adapter be tested for this? I'm not concerned, but as you obviously are, then it would seem best to use the branded manufacturers lead, but I wouldn't bother myself as never had any problem. Just connect the ciggy plug first to prevent any problem with the power going on and off rapidly while the equipment is connected. Thanks for the response. I'm not so much "concerned" as ignorant! and seeking advice as to whether it's an issue or not. I've certainly used quite a few adaptors myself for different deviced without problems, and other than *possibly* a camping fridge which expired under warranty under dubious circumstances. I've recently bought a notebook computer which would be by far the most expensive device to charge from the car; hence the current interest. David |
12V car cig lighter adapters - safe?
On Jul 28, 9:50*pm, Lobster wrote:
Graham wrote: "Lobster" wrote in message ... My family have a fair number of electrical devices ranging from mobile phones to electronic games to fridges, all of which lend themselves to being able to be powered or charged on the road by a 12V cigarette lighter adapter. My question is, how safe are these adapters in terms of risking possible damage to the device in question? I've never had any problem with damage to delicate equipment like phones or satnav. Its a wise precaution to connect the ciggy plug before connecting the equipment just incase the power goes on and off a few times as you plug it in, but I've never had any problem. I read about 'surges' in power from the car; if so, is it down to circuitry built in to the device in question to protect itself from that? *Or should such protection be built into the actual adapter? Varies. Some adaptor leads have a regulator inside to bring voltage down to what the equipment needs and this will give protection, but from what? Alternator going overvolts will be sunk into the battery, so impossible to go above the battery terminal voltage. Is it risky to buy a 'cheapo' aftermarket adapter in place of the device manufacturer - might that be a more dangerous proposition than buying an 'original' item? *If so, how can you tell what's safe, other than by spending as much cash as possible? *Can an existing adapter be tested for this? I'm not concerned, but as you obviously are, then it would seem best to use the branded manufacturers lead, but I wouldn't bother myself as never had any problem. Just connect the ciggy plug first to prevent any problem with the power going on and off rapidly while the equipment is connected. Thanks for the response. *I'm not so much "concerned" as ignorant! *and seeking advice as to whether it's an issue or not. *I've certainly used quite a few adaptors myself for different deviced without problems, and other than *possibly* a camping fridge which expired under warranty under dubious circumstances. *I've recently bought a notebook computer which would be by far the most expensive device to charge from the car; hence the current interest. David Its certainly an issue, car electrics are very hostile in terms of transients, and lots of appliances just dont survive them. FWIW if the car is switched off the nasty transients dont happen, but thats a less than reliable way to avoid the problem. Consider the cost of incorporating protection into an adaptor, and what youre paying for one. I'd be cautious before running anything not bulletproof on car 12v, as for a laptop noooooo. If the appliance in question comes with a car connector then its usually designed to tolerate car supplies, but if not its a risky strategy. If you want to run masses of appliances from the car, a small SLA with a 2 way switch would solve the problem - the switch enables it to connect to either car electrics or appliance, but never both. 12v SLAs tolerate lower charge voltage than car batteries, so a series diode would be wanted. Nicads could also be used in pricniple, but there are then more complex charging issues to deal with. NT |
12V car cig lighter adapters - safe?
i think the biggest danger with 12volt devices
is of fire, if a wire is too thin it can get hot and burn plastic - it happened to me with my car second battery charger- i had a fuse on one battery but not on the second- whooops -- [george] ~ |
12V car cig lighter adapters - safe?
In article ,
Lobster wrote: My family have a fair number of electrical devices ranging from mobile phones to electronic games to fridges, all of which lend themselves to being able to be powered or charged on the road by a 12V cigarette lighter adapter. My question is, how safe are these adapters in terms of risking possible damage to the device in question? I read about 'surges' in power from the car; if so, is it down to circuitry built in to the device in question to protect itself from that? Or should such protection be built into the actual adapter? I'm not quite sure how you'd get 'surges' in power in a car, given it has an extremely low impedance vast capacitor sitting across the line - the battery. And I'd also say anything fitted with a fag lighter plug is designed to work with car electrics - it's not a standard used elsewhere. So yes - most will have some form of regulation either in the plug or the device itself, as phones and Tom Toms etc don't have 12 volt internal batteries. Is it risky to buy a 'cheapo' aftermarket adapter in place of the device manufacturer - might that be a more dangerous proposition than buying an 'original' item? If so, how can you tell what's safe, other than by spending as much cash as possible? Can an existing adapter be tested for this? You mean a connecting lead for say a phone which isn't a genuine maker's accessory? Could be anything. So I'd buy it from a reputable source. Thanks David -- *Is there another word for synonym? Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
In article
, wrote: Its certainly an issue, car electrics are very hostile in terms of transients, and lots of appliances just dont survive them. What, for example? Most of the things you plug into a fag socket don't actually run off 12 volts so will have voltage regulation somewhere - either internal or in the lead. And a standard regulator will cope with about 40 volts. Most cars these days are packed with electronics. They seem to survive this 'hostile' environment ok. -- *One of us is thinking about sex... OK, it's me. Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
On Tue, 29 Jul 2008 00:27:12 +0100, Dave Plowman (News)
wrote: In article , wrote: Its certainly an issue, car electrics are very hostile in terms of transients, and lots of appliances just dont survive them. What, for example? Most of the things you plug into a fag socket don't actually run off 12 volts so will have voltage regulation somewhere - either internal or in the lead. And a standard regulator will cope with about 40 volts. Most cars these days are packed with electronics. They seem to survive this 'hostile' environment ok. & if the batteries connected it provides rather good transient protection. |
12V car cig lighter adapters - safe?
Dave Plowman (News) wrote:
[...] I'm not quite sure how you'd get 'surges' in power in a car, given it has an extremely low impedance vast capacitor sitting across the line - the battery. Unless the battery terminal to cable connection is poor, of course! ;-) Chris -- Remove prejudice to reply. |
12V car cig lighter adapters - safe?
"George (dicegeorge)" wrote in message ... i think the biggest danger with 12volt devices is of fire, if a wire is too thin it can get hot and burn plastic - it happened to me with my car second battery charger- i had a fuse on one battery but not on the second- whooops That is why there should always be a fuse as close to the battery as possible. Close to battery so there is only the smallest length of wire unprotected from a short should the insulation chaff and touch the body. Its surprising how often long lengths are left completely unprotected or naively fused at the far end. By all means fuse at lower amperage at the far end, but there must always be a fuse at the battery end to blow if a short to the body along the cable run. These days cars have a fusible link next to the battery terminal, but this is designed to stop wiring catching fire and a very high current rating, so not to be relied on for protection. Pick up power after the fuse box or if for some reason its needed to connect directly to the battery, say because its a very powerful piece of equipment like an inverter or ridiculously powerful car audio system, then put a fuse within an inch or two of the battery. Graham |
12V car cig lighter adapters - safe?
In article ,
George \(dicegeorge\) wrote: i think the biggest danger with 12volt devices is of fire, if a wire is too thin it can get hot and burn plastic - it happened to me with my car second battery charger- i had a fuse on one battery but not on the second- whooops Fag lighter adaptors have a fuse built in. But simply don't use wire not up to the job in hand. -- *Growing old is inevitable, growing up is optional Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
Graham wrote:
Varies. Some adaptor leads have a regulator inside to bring voltage down to what the equipment needs and this will give protection, but from what? Alternator going overvolts will be sunk into the battery, so impossible to go above the battery terminal voltage. Utter and total bull****e. -- Dave GS850x2 XS650 SE6a "It's a moron working with power tools. How much more suspenseful can you get?" - House |
12V car cig lighter adapters - safe?
On Mon, 28 Jul 2008 18:46:34 +0100, Lobster
wrote: My question is, how safe are these adapters in terms of risking possible damage to the device in question? I read about 'surges' in power from the car; snip AFAIK The main source of surge/spike is when the starter motor stops turning - all those amps used to create the magnetic field have to go somewhere fast... On light aircraft, the rule is all avionics OFF until the engine has started. I neglected to turn off one item once and was rewarded with a fascinating display of random numbers/symbols (luckily no permanent damage) Just checked my car - the radio and cigar lighter power is disconnected from the supply while the engine is being started. I think you would probably be ok but if in doubt, just pull the plug out until engine running - this assumes you don't have any unusual heavy electrical items connected e.g. motors, large solenoids etc. Geo |
12V car cig lighter adapters - safe?
On Jul 29, 12:27*am, "Dave Plowman (News)"
wrote: In article , * wrote: Its certainly an issue, car electrics are very hostile in terms of transients, and lots of appliances just dont survive them. What, for example? Anything electronic that isnt specifically designed to run on car systems. Also some things that are - cost cutting invertors for example tend to lack the ability to survive all transients, hence wont last forever. *Most of the things you plug into a fag socket don't actually run off 12 volts so will have voltage regulation somewhere - either internal or in the lead. And a standard regulator will cope with about 40 volts. which isnt sufficient. *Most cars these days are packed with electronics. They seem to survive this 'hostile' environment ok. Theyre designed to. They have input filters that can cope with +_60v. Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. NT |
12V car cig lighter adapters - safe?
Geo wrote:
On Mon, 28 Jul 2008 18:46:34 +0100, Lobster wrote: My question is, how safe are these adapters in terms of risking possible damage to the device in question? I read about 'surges' in power from the car; snip AFAIK The main source of surge/spike is when the starter motor stops turning - all those amps used to create the magnetic field have to go somewhere fast... On light aircraft, the rule is all avionics OFF until the engine has started. I neglected to turn off one item once and was rewarded with a fascinating display of random numbers/symbols (luckily no permanent damage) Just checked my car - the radio and cigar lighter power is disconnected from the supply while the engine is being started. I think you would probably be ok but if in doubt, just pull the plug out until engine running - this assumes you don't have any unusual heavy electrical items connected e.g. motors, large solenoids etc. Geo But would that apply if, for example, you were trying to restart the engine in flight? -- Rod Hypothyroidism is a seriously debilitating condition with an insidious onset. Although common it frequently goes undiagnosed. www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org |
12V car cig lighter adapters - safe?
In article
, wrote: Its certainly an issue, car electrics are very hostile in terms of transients, and lots of appliances just dont survive them. What, for example? Anything electronic that isnt specifically designed to run on car systems. Then it won't come with a fag lighter plug? Also some things that are - cost cutting invertors for example tend to lack the ability to survive all transients, hence wont last forever. More likely damaged by overload. You'd be hard pressed to find mosfets that can be damaged by the sort of voltage spikes found in a car. Most of the things you plug into a fag socket don't actually run off 12 volts so will have voltage regulation somewhere - either internal or in the lead. And a standard regulator will cope with about 40 volts. which isnt sufficient. Then every other piece of electronics will die too. Have you never built any car electronics - or is this some theory plucked from the air? Most cars these days are packed with electronics. They seem to survive this 'hostile' environment ok. Theyre designed to. They have input filters that can cope with +_60v. Ah so now we have a figure. Can I ask where the 60 volts comes from? Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. There's lots of these theories doing the rounds that simply don't happen in practice. And yes, I have looked at several car systems with a 'scope. Of course you get rubbish on it otherwise there's be no need to filter amplifier supplies etc - but those spikes ain't capable of doing damage. -- *I didn't fight my way to the top of the food chain to be a vegetarian. Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
On Tue, 29 Jul 2008 13:06:40 +0100, Rod wrote:
But would that apply if, for example, you were trying to restart the engine in flight? Yes - the only supply required from the battery is the starter motor - ignition is from two independent magnetos (2 plugs per cylinder). Geo |
12V car cig lighter adapters - safe?
Geo wrote:
On Tue, 29 Jul 2008 13:06:40 +0100, Rod wrote: But would that apply if, for example, you were trying to restart the engine in flight? Yes - the only supply required from the battery is the starter motor - ignition is from two independent magnetos (2 plugs per cylinder). Geo I meant, would it be OK to turn off all avionics while struggling to get the engine running again. I imagine that would include altimeter, radio, etc.? I know nothing about aircraft but am thinking that the systems will be broadly similar to cars - when the engine is not running, all ancillary equipment will run off battery? -- Rod Hypothyroidism is a seriously debilitating condition with an insidious onset. Although common it frequently goes undiagnosed. www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org |
12V car cig lighter adapters - safe?
On Tue, 29 Jul 2008 13:43:18 +0100, Rod wrote:
I meant, would it be OK to turn off all avionics while struggling to get the engine running again. I imagine that would include altimeter, radio, etc.? Yes - I am talking small (say 4 seat) aircraft in good weather. The aircraft will fly with basic instruments without battery power. Altimeter, airspeed and compass. Generally only two flight instruments are battery powered (in common Cessnas/Pipers) the direction indicator gyro and the turn/slip indicator. The other (avionics)stuff is mostly for flying when you can't see anything out of the window. I know nothing about aircraft but am thinking that the systems will be broadly similar to cars - when the engine is not running, all ancillary equipment will run off battery? That is correct - in the event of alternator failure (for example) all unecessary stuff is switched off to conserve battery power for a couple of radio calls before landing at the nearest airfield. Geo |
12V car cig lighter adapters - safe?
On Tue, 29 Jul 2008 13:20:43 +0100, Dave Plowman (News)
wrote: In article , wrote: Its certainly an issue, car electrics are very hostile in terms of transients, and lots of appliances just dont survive them. What, for example? Anything electronic that isnt specifically designed to run on car systems. Then it won't come with a fag lighter plug? Also some things that are - cost cutting invertors for example tend to lack the ability to survive all transients, hence wont last forever. More likely damaged by overload. You'd be hard pressed to find mosfets that can be damaged by the sort of voltage spikes found in a car. Most of the things you plug into a fag socket don't actually run off 12 volts so will have voltage regulation somewhere - either internal or in the lead. And a standard regulator will cope with about 40 volts. which isnt sufficient. Then every other piece of electronics will die too. Have you never built any car electronics - or is this some theory plucked from the air? Most cars these days are packed with electronics. They seem to survive this 'hostile' environment ok. Theyre designed to. They have input filters that can cope with +_60v. Ah so now we have a figure. Can I ask where the 60 volts comes from? Last time looked it was 55V (TI automotive spec for semiconducters) Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. There's lots of these theories doing the rounds that simply don't happen in practice. And yes, I have looked at several car systems with a 'scope. Of course you get rubbish on it otherwise there's be no need to filter amplifier supplies etc - but those spikes ain't capable of doing damage. Well the installed stuff's normally designed to cope with far worse situations than you normally ever see. But if you're worried a couple of 16V Zeners or VDRs are hardly expensive. |
12V car cig lighter adapters - safe?
On Tue, 29 Jul 2008 12:39:44 +0100, Geo wrote:
On Mon, 28 Jul 2008 18:46:34 +0100, Lobster wrote: My question is, how safe are these adapters in terms of risking possible damage to the device in question? I read about 'surges' in power from the car; snip AFAIK The main source of surge/spike is when the starter motor stops turning - all those amps used to create the magnetic field have to go somewhere fast... Across the switch contacts unless you've wired it oddly. On light aircraft, the rule is all avionics OFF until the engine has started. I neglected to turn off one item once and was rewarded with a fascinating display of random numbers/symbols (luckily no permanent damage) Just checked my car - the radio and cigar lighter power is disconnected from the supply while the engine is being started. That's to maximise the available current though :-) I think you would probably be ok but if in doubt, just pull the plug out until engine running - this assumes you don't have any unusual heavy electrical items connected e.g. motors, large solenoids etc. Geo |
12V car cig lighter adapters - safe?
On 29 Jul, 14:36, "Duncan Wood" wrote:
On Tue, 29 Jul 2008 12:39:44 +0100, Geo wrote: On Mon, 28 Jul 2008 18:46:34 +0100, Lobster * wrote: My question is, how safe are these adapters in terms of risking possible damage to the device in question? *I read about 'surges' in power from the car; snip AFAIK The main source of surge/spike is when the starter motor stops turning - * all those amps used to create the magnetic field have to go somewhere fast.... Across the switch contacts unless you've wired it oddly. On light aircraft, the rule is all avionics OFF until the engine has * started. I neglected to turn off one item once and was rewarded with a fascinating display of random numbers/symbols (luckily no permanent damage) Just checked my car - the radio and cigar lighter power is disconnected * from the supply while the engine is being started. My past satnav had definite instruction that not to plug in, until car started. My current Tom Tom has no such request. That's to maximise the available current though :-) I think you would probably be ok but if in doubt, just pull the plug out * until engine running - this assumes you don't have any unusual heavy * electrical items connected e.g. motors, large solenoids etc. Geo- Hide quoted text - - Show quoted text - |
12V car cig lighter adapters - safe?
On 29 Jul, 17:42, Gel wrote:
On 29 Jul, 14:36, "Duncan Wood" wrote: On Tue, 29 Jul 2008 12:39:44 +0100, Geo wrote: On Mon, 28 Jul 2008 18:46:34 +0100, Lobster * wrote: My question is, how safe are these adapters in terms of risking possible damage to the device in question? *I read about 'surges' in power from the car; snip AFAIK The main source of surge/spike is when the starter motor stops turning - * all those amps used to create the magnetic field have to go somewhere fast... Across the switch contacts unless you've wired it oddly. On light aircraft, the rule is all avionics OFF until the engine has * started. I neglected to turn off one item once and was rewarded with a fascinating display of random numbers/symbols (luckily no permanent damage) Just checked my car - the radio and cigar lighter power is disconnected * from the supply while the engine is being started. My past satnav had definite instruction that not to plug in, until car started. My current Tom Tom has no such request. That's to maximise the available current though :-) I think you would probably be ok but if in doubt, just pull the plug out * until engine running - this assumes you don't have any unusual heavy * electrical items connected e.g. motors, large solenoids etc. Geo- Hide quoted text - - Show quoted text - There's lots of good comments here and several concerns that are based on urban myth. Just as much as there will be filtering on the inputs to car electronic boxes, there will be powerful filtering across the likes of the starter motor, etc. EMC/RFI testing looks at the response on the inputs to surges, spikes, etc, but also makes sure that supply lines and the likes do not generate and propagate interference. So testing is a two way activity - in and out. The real cruncher is that no-one at all has made a statement about experiencing any such failures - or knowing anyone who has, or hearing of any such failure through the likes of this inter-webby thing. The conclusion surely is therefore that it just doesn't happen. I quite happily have my satnav and mobile on charge while starting and driving - I would really doubt that anyone would want to have a laptop running while starting the car, but as they too have a dirty great 'capacitor' across the supply I wouldn't have thought problems would have occurred. Rob |
12V car cig lighter adapters - safe?
In article op.ue12mknhhaghkf@lucy,
Duncan Wood wrote: Ah so now we have a figure. Can I ask where the 60 volts comes from? Last time looked it was 55V (TI automotive spec for semiconducters) I gave the figure of 40 volts for a bog standard regulator - but of course that's the differential. So if regulating to 9 volts the peak would be 49. And of course it's simple to increase this if needed. -- *The colder the X-ray table, the more of your body is required on it * Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
On 2008-07-29, Duncan Wood wrote:
On Tue, 29 Jul 2008 13:20:43 +0100, Dave Plowman (News) wrote: In article , wrote: Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. There's lots of these theories doing the rounds that simply don't happen in practice. And yes, I have looked at several car systems with a 'scope. Of course you get rubbish on it otherwise there's be no need to filter amplifier supplies etc - but those spikes ain't capable of doing damage. Well the installed stuff's normally designed to cope with far worse situations than you normally ever see. But if you're worried a couple of 16V Zeners or VDRs are hardly expensive. My opinion would be that most stuff without a particularly fragile voltage regulator would be fine running on 12V from the cigarette lighter socket. OTOH, devices which have sensor wires running all over the car (not your general in-car entertainment devices, etc.) may have problems. They have to be designed to withstand a lot of noise on any signals and potentially harmful induced voltages on inputs. -- David Taylor |
12V car cig lighter adapters - safe?
"robgraham" wrote in message news:1ca0f39d-cf87-41c4-b8bc- The real cruncher is that no-one at all has made a statement about experiencing any such failures - or knowing anyone who has, or hearing of any such failure through the likes of this inter-webby thing. The conclusion surely is therefore that it just doesn't happen. I quite happily have my satnav and mobile on charge while starting and driving - I would really doubt that anyone would want to have a laptop running while starting the car, but as they too have a dirty great 'capacitor' across the supply I wouldn't have thought problems would have occurred. Agreed. I have used all sorts of vulnerable equipment in all sorts of cars going back 30 years and never had any hint of the car causing spikes that could damage anything. I've been building all sorts of electronic stuff for years and long before regulators were available in a single 3 pin package so most of the stuff didn't have a regulator and was designed to run straight off the car. The only time you would go to the trouble of actually building a regulator was if it needed a fixed voltage for stable operator as in an oscillator for instance. I'd find it difficult to list all the equipment I've used in the car, but it goes from valve transmitters, through to home built transistor transmitters and receivers, transistor RF power amps, boards with switching and logic and god knows what else. Never has the car enviroment been problem beyond the slightly varying supply voltage, possible RF interferrence from ignition and protection from reverse polarity of the supply leads. Never has anything gone bang when starting the car due to the starter motor back emf. I have never encountered any mention of that in all the electronic/communications/broadcasting companies I have worked for and frankly think it gets sinked back into the battery long before it could do any damage. Its just never been an issue anyone has ever mentioned as it is not a problem anyone has had. Graham |
12V car cig lighter adapters - safe?
On Jul 29, 1:20*pm, "Dave Plowman (News)"
wrote: In article , * wrote: Its certainly an issue, car electrics are very hostile in terms of transients, and lots of appliances just dont survive them. What, for example? Anything electronic that isnt specifically designed to run on car systems. Then it won't come with a fag lighter plug? Also some things that are - cost cutting invertors for example tend to lack the ability to survive all transients, hence wont last forever. More likely damaged by overload. You'd be hard pressed to find mosfets that can be damaged by the sort of voltage spikes found in a car. * *Most of the things you plug into a fag socket don't actually run off 12 volts so will have voltage regulation somewhere - either internal or in the lead. And a standard regulator will cope with about 40 volts. which isnt sufficient. Then every other piece of electronics will die too. Have you never built any car electronics - or is this some theory plucked from the air? * *Most cars these days are packed with electronics. They seem to survive this 'hostile' environment ok. Theyre designed to. They have input filters that can cope with +_60v. Ah so now we have a figure. Can I ask where the 60 volts comes from? * Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. There's lots of these theories doing the rounds that simply don't happen in practice. And yes, I have looked at several car systems with a 'scope. * Of course you get rubbish on it otherwise there's be no need to filter amplifier supplies etc - but those spikes ain't capable of doing damage. How did you trigger the load dump events for these measurements? NT |
12V car cig lighter adapters - safe?
wrote in message ... On Jul 29, 1:20 pm, "Dave Plowman (News)" wrote: In article , wrote: Its certainly an issue, car electrics are very hostile in terms of transients, and lots of appliances just dont survive them. What, for example? Anything electronic that isnt specifically designed to run on car systems. Then it won't come with a fag lighter plug? Also some things that are - cost cutting invertors for example tend to lack the ability to survive all transients, hence wont last forever. More likely damaged by overload. You'd be hard pressed to find mosfets that can be damaged by the sort of voltage spikes found in a car. Most of the things you plug into a fag socket don't actually run off 12 volts so will have voltage regulation somewhere - either internal or in the lead. And a standard regulator will cope with about 40 volts. which isnt sufficient. Then every other piece of electronics will die too. Have you never built any car electronics - or is this some theory plucked from the air? Most cars these days are packed with electronics. They seem to survive this 'hostile' environment ok. Theyre designed to. They have input filters that can cope with +_60v. Ah so now we have a figure. Can I ask where the 60 volts comes from? Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. There's lots of these theories doing the rounds that simply don't happen in practice. And yes, I have looked at several car systems with a 'scope. Of course you get rubbish on it otherwise there's be no need to filter amplifier supplies etc - but those spikes ain't capable of doing damage. How did you trigger the load dump events for these measurements? What??? He stuck a scope across the suppy and looked at the noise and spikes. End off. Graham |
12V car cig lighter adapters - safe?
In article ,
Graham wrote: I'd find it difficult to list all the equipment I've used in the car, but it goes from valve transmitters, through to home built transistor transmitters and receivers, transistor RF power amps, boards with switching and logic and god knows what else. Never has the car enviroment been problem beyond the slightly varying supply voltage, possible RF interferrence from ignition and protection from reverse polarity of the supply leads. Never has anything gone bang when starting the car due to the starter motor back emf. I have never encountered any mention of that in all the electronic/communications/broadcasting companies I have worked for and frankly think it gets sinked back into the battery long before it could do any damage. Its just never been an issue anyone has ever mentioned as it is not a problem anyone has had. My experience too. -- *Reality is the illusion that occurs due to the lack of alcohol * Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
In article
, wrote: Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. There's lots of these theories doing the rounds that simply don't happen in practice. And yes, I have looked at several car systems with a 'scope. Of course you get rubbish on it otherwise there's be no need to filter amplifier supplies etc - but those spikes ain't capable of doing damage. How did you trigger the load dump events for these measurements? I didn't. I simply don't go around disconnecting alternators with the engine running. I try and design stuff to be foolproof, idiot proof even - but not c**t proof. -- *I'm not a complete idiot, some parts are missing * Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
On Jul 28, 7:23*pm, "Dave Plowman (News)"
wrote: I'm not quite sure how you'd get 'surges' in power in a car, given it has an extremely low impedance vast capacitor sitting across the line - the battery. Assumptions contradict well proven standards. Load dump is defined up to 270 volts on the 12 volts. All car electronics includes designs to make load dump irrelevant. But some appliances selling on the cheap may simply forget that option. Most all semiconductor manufacturers make power supply chips so that 12 volts can supply regulated voltages to electronics. Then they make special versions for automotive use due to higher voltages such as load dump. National Semiconductor has a specific line just for automotive use. Does you adaptor manufacturer used the standard and cheap voltage regulators - or those designed for automotive use. Standards that define load dump including SAE J1455 and ISO 7637-1. Load dump can be defined by: Peak voltage 80 to 100 volts Duration 300 to 400 milliseconds Series resistance 0.2 to 1 ohms Some designs call for a protection circuit that can withstand up to 270 volts and 50 joules. Why do some manufacturers sell the equivalent 12 volt power source for more money? What does the manufacturer spec say about load dump? |
12V car cig lighter adapters - safe?
On Jul 29, 11:54*pm, w_tom wrote:
On Jul 28, 7:23*pm, "Dave Plowman (News)" wrote: I'm not quite sure how you'd get 'surges' in power in a car, given it has an extremely low impedance vast capacitor sitting across the line - the battery. * Assumptions contradict well proven standards. *Load dump is defined up to 270 volts on the 12 volts. *All car electronics includes designs to make load dump irrelevant. *But some appliances selling on the cheap may simply forget that option. * Most all semiconductor manufacturers make power supply chips so that 12 volts can supply regulated voltages to electronics. *Then they make special versions for automotive use due to higher voltages such as load dump. *National Semiconductor has a specific line just for automotive use. *Does you adaptor manufacturer used the standard and cheap voltage regulators - or those designed for automotive use. Very often, there's feck all difference between parts supplied for normal or other environments. It's just not economical to do otherwise. Look at the way the supply of "military" grade silicon virtually disappeared. Selling into the automotive market relies on implementing, and being able to prove you've implemented very strict QA processes. Another aspect is traceability of supply. Don't even mention the liability terms that automotive manufacturers will try to apply. MBQ |
12V car cig lighter adapters - safe?
On Jul 29, 11:27*pm, "Dave Plowman (News)"
wrote: In article , * wrote: Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. There's lots of these theories doing the rounds that simply don't happen in practice. And yes, I have looked at several car systems with a 'scope. * Of course you get rubbish on it otherwise there's be no need to filter amplifier supplies etc - but those spikes ain't capable of doing damage. How did you trigger the load dump events for these measurements? I didn't. I simply don't go around disconnecting alternators with the engine running. I try and design stuff to be foolproof, idiot proof even - but not c**t proof. That would explain your failure to see the spikes. Try repeatedly switching off the rear window heater while measuring next time. Then try it for real: switch off all accessories and waggle the loose battery connection. Dont have your laptop connected :) If the op wants to play chance games with their lappy they can, but at least they're more aware of the problem now. If these events didnt occur IRL no-one would write about them, and car electronics designers wouldnt design equipment to withstand them. They do. NT |
12V car cig lighter adapters - safe?
On Jul 29, 8:53*pm, "Graham" wrote:
"robgraham" wrote in message news:1ca0f39d-cf87-41c4-b8bc- The real cruncher is that no-one at all has made a statement about experiencing any such failures - or knowing anyone who has, or hearing of any such failure through the likes of this inter-webby thing. *The conclusion surely is therefore that it just doesn't happen. I quite happily have my satnav and mobile on charge while starting and driving - I would really doubt that anyone would want to have a laptop running while starting the car, but as they too have a dirty great 'capacitor' across the supply I wouldn't have thought problems would have occurred. Agreed. I have used all sorts of vulnerable equipment in all sorts of cars going back 30 years and never had any hint of the car causing spikes that could damage anything. I've been building all sorts of electronic stuff for years and long before regulators were available in a single 3 pin package so most of the stuff didn't have a regulator and was designed to run straight off the car. The only time you would go to the trouble of actually building a regulator was if it needed a fixed voltage for stable operator as in an oscillator for instance. I'd find it difficult to list all the equipment I've used in the car, but it goes from valve transmitters, through to home built transistor transmitters and receivers, transistor RF power amps, boards with switching and logic and god knows what else. Never has the car enviroment been *problem beyond the slightly varying supply voltage, possible RF interferrence from ignition and protection from reverse polarity of the supply leads. Never has anything gone bang when starting the car due to the starter motor back emf. I have never encountered any mention of that in all the electronic/communications/broadcasting companies I *have worked for and frankly think it gets sinked back into the battery long before it could do any damage. Its just never been an issue anyone has ever mentioned as it is not a problem anyone has had. Graham Disconnection of the starter motor is not the problem. The inductive current source is the alternator, and this is producing more or less nothing during starting. NT |
12V car cig lighter adapters - safe?
On Wed, 30 Jul 2008 13:53:04 +0100, wrote:
On Jul 29, 11:27*pm, "Dave Plowman (News)" wrote: In article , * wrote: Cars have a high current inductive power source, the alternator, and the battery isnt close enough to eliminate substantial high frequency overvoltage transients in the event of load dump. This is fairly basic electronics stuff, maybe the OP should ask in sci.electronics.basics. Diy and electronics really are 2 different animals, and ukdiy is not an electronics expert group. There's lots of these theories doing the rounds that simply don't happen in practice. And yes, I have looked at several car systems with a 'scope. * Of course you get rubbish on it otherwise there's be no need to filter amplifier supplies etc - but those spikes ain't capable of doing damage. How did you trigger the load dump events for these measurements? I didn't. I simply don't go around disconnecting alternators with the engine running. I try and design stuff to be foolproof, idiot proof even - but not c**t proof. That would explain your failure to see the spikes. Try repeatedly switching off the rear window heater while measuring next time. Then try it for real: switch off all accessories and waggle the loose battery connection. Dont have your laptop connected :) If the op wants to play chance games with their lappy they can, but at least they're more aware of the problem now. If these events didnt occur IRL no-one would write about them, and car electronics designers wouldnt design equipment to withstand them. They do. NT Most of us here don't have loose battery connections. |
12V car cig lighter adapters - safe?
wrote in message ... On Jul 29, 8:53 pm, "Graham" wrote: "robgraham" wrote in message news:1ca0f39d-cf87-41c4-b8bc- The real cruncher is that no-one at all has made a statement about experiencing any such failures - or knowing anyone who has, or hearing of any such failure through the likes of this inter-webby thing. The conclusion surely is therefore that it just doesn't happen. I quite happily have my satnav and mobile on charge while starting and driving - I would really doubt that anyone would want to have a laptop running while starting the car, but as they too have a dirty great 'capacitor' across the supply I wouldn't have thought problems would have occurred. Agreed. I have used all sorts of vulnerable equipment in all sorts of cars going back 30 years and never had any hint of the car causing spikes that could damage anything. I've been building all sorts of electronic stuff for years and long before regulators were available in a single 3 pin package so most of the stuff didn't have a regulator and was designed to run straight off the car. The only time you would go to the trouble of actually building a regulator was if it needed a fixed voltage for stable operator as in an oscillator for instance. I'd find it difficult to list all the equipment I've used in the car, but it goes from valve transmitters, through to home built transistor transmitters and receivers, transistor RF power amps, boards with switching and logic and god knows what else. Never has the car enviroment been problem beyond the slightly varying supply voltage, possible RF interferrence from ignition and protection from reverse polarity of the supply leads. Never has anything gone bang when starting the car due to the starter motor back emf. I have never encountered any mention of that in all the electronic/communications/broadcasting companies I have worked for and frankly think it gets sinked back into the battery long before it could do any damage. Its just never been an issue anyone has ever mentioned as it is not a problem anyone has had. Graham Disconnection of the starter motor is not the problem. The inductive current source is the alternator, and this is producing more or less nothing during starting. So as previously stated, there is no problem. You carry on with your bad self and I'll carry on without the problems I've not had. Graham |
12V car cig lighter adapters - safe?
In article
, wrote: I didn't. I simply don't go around disconnecting alternators with the engine running. I try and design stuff to be foolproof, idiot proof even - but not c**t proof. That would explain your failure to see the spikes. Try repeatedly switching off the rear window heater while measuring next time. What's that supposed to do? Then try it for real: switch off all accessories and waggle the loose battery connection. Dont have your laptop connected :) Err, why are you deliberately introducing a red herring? If a battery terminal is loose the car won't start. If the op wants to play chance games with their lappy they can, but at least they're more aware of the problem now. You use a laptop on the move? Takes all types. If these events didnt occur IRL no-one would write about them, and car electronics designers wouldnt design equipment to withstand them. They do. Including the PS built into the fag lighter adaptor? I'm not denying you could possibly mess up something by adapting it to run off a fag lighter socket - but that wasn't the question. And I've got lots of home designed electronics in one car where I made absolutely no provision for the sort of over voltage you imply. Without failure. -- *If you ate pasta and anti-pasta, would you still be hungry? Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
In article op.ue3wiyg6haghkf@lucy,
Duncan Wood wrote: Most of us here don't have loose battery connections. And if we did the car wouldn't start which means 'current dump' into an accessory couldn't happen... -- *According to my calculations, the problem doesn't exist. Dave Plowman London SW To e-mail, change noise into sound. |
12V car cig lighter adapters - safe?
In article , Dave Plowman (News)
says... Never has anything gone bang when starting the car due to the starter motor back emf. I have never encountered any mention of that in all the electronic/communications/broadcasting companies I have worked for and frankly think it gets sinked back into the battery long before it could do any damage. Its just never been an issue anyone has ever mentioned as it is not a problem anyone has had. My experience too. And last night I started my Renault Premium which had my Satnav plugged into the 24V socket and a 300W Mains Inverter plugged into the 12V socket and my lappy plugged into that. Apart from them cutting out momentarily as the ignition key changed positions, they kept working throughout. It's not the first time I've done it either. At one point, it was happening several times a night when I was doing a night trunk for a pallet company. Lappy is still working fine, inverter is still working fine. So is moby and Satnav. And I can guarantee that any back EMF you'd get from a 24V starter motor on a 12 litre diesel engine is going to far exceed anything you'd get from a poxy car one. -- Conor I only please one person per day. Today is not your day. Tomorrow isn't looking good either. - Scott Adams |
12V car cig lighter adapters - safe?
In article cc3c2337-405c-4e1c-9c7e-35359c976734
@b1g2000hsg.googlegroups.com, says... That would explain your failure to see the spikes. Try repeatedly switching off the rear window heater while measuring next time. Then try it for real: switch off all accessories and waggle the loose battery connection. Dont have your laptop connected :) **** all happened. Difference is I had the night heater in the truck instead of a heated window. A night heater is a bit of kit which has an electrode which heats up diesel and a fan to blow the resulting hot air into the cab. Works like central heating in the fact that you set a temperature and it comes on and off to maintain that. A night heater draws more current than a window heater and the electrical noise from the fan far exceeds that of the window heater to the point where it can be seen as RF interference on a TV. And my laptop still works. So again, you're talking out of your arse. -- Conor I only please one person per day. Today is not your day. Tomorrow isn't looking good either. - Scott Adams |
12V car cig lighter adapters - safe?
In article , Dave Plowman (News)
says... You use a laptop on the move? Takes all types. I use my laptop in my lorry. Its exposed to far more electrical noise and far higher potential back EMF than you'd get in a car yet my lappy is working fine. -- Conor I only please one person per day. Today is not your day. Tomorrow isn't looking good either. - Scott Adams |
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