OzSTOC
Honda ST1100 Section => Electrics & Electronics - Volts, Amps and Fuses ST1100 => Topic started by: Diesel on September 28, 2012, 08:12:57 AM
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If this fusebox......
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=221128206855&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en#ht_574wt_1397 (http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=221128206855&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en#ht_574wt_1397)
says that it is rated at 20 amps max per fuse - then should I run a 30A constant power cable to it from my battery with a 20A in line fuse?
i.e. the multiple circuits on thhis line can't overload a 30A wire can they? :o
Cheers, Diesel
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If you use a 30Amp supply line, then the in line fuse should be 30A to protect the wire. Each fuse in the blockl can be anything up to 20 A, if you have a 3Amp item, then a 5 A fuse would be fine. Not many items on the bike would need 20 amps.
remember, the total that the alternator can supply is 40 Amps, any draw more than this will start to drain the battery which means no start, and the bike will eventually stop.
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Thanks Brock - here is some text I nicked from Whizz when commenting on Shiney's power socket installation:
Ohms Law says that Power equals Voltage multiplied by current, or P=V x I. This transposes to I=P/V or 60/12, so the headlight draws 5A when on high beam (4.58A on low beam). This means that the maximum current you can draw from your new accessories block, with the headlight on is 5A, not as you might think 10A (from the size of the fuse).
So you need to be a little careful what you plug into these sockets because the headlight is on all the time, day and night! Not forgetting that the current draw is cumulative, i.e. you add together all the currents required by all the accessories that you plug in at any one time to get the total current requirement. Under these circumstances it is really quite easy to pop a 10A fuse, especially as there is a significant surge current requirement when you first turn on your ignition. This means that when you turn the key the headlight appears as a dead short and draws a hefty spike of current to make the lamp glow. If you also have other stuff plugged in which also has surge currents then that is the moment when the fuse is most likely to blow. There is an old adage that says that a light bulb only blows when you turn it on and this is simply because of the surge current required to make an incandescent bulb glow white hot.
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So - to use this fuse block.....
http://www.ebay.com.au/itm/221128206706?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649&autorefresh=true#ht_574wt_1398 (http://www.ebay.com.au/itm/221128206706?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649&autorefresh=true#ht_574wt_1398)
I should go:
Battery ----> 30A wire --------> 30A Relay --------> Fuse Block --------> acessories (load)
Yes? - Do I really need the relay in there?
Cheers, Diesel
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The relay is only needed if the devices you want to power are only used when the ignition is on. If you want to power items when the bike is off, no.
The relay could be energised (turned on ) by the tail light, it will add no load to speak of to the tail light.
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As Brock says. Depends what devices you are planning to power. The total output of the fusebox should not exceed the wire and fuse powering it, otherwise the fuse going to the fusebox will blow to protect the wire. The fuse for each device does not have to be 20amp, just what is required to protect the device/wiring to it.
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Thanks Brock - here is some text I nicked from Whizz when commenting on Shiney's power socket installation:
Ohms Law says that Power equals Voltage multiplied by current, or P=V x I. This transposes to I=P/V or 60/12, so the headlight draws 5A when on high beam (4.58A on low beam). This means that the maximum current you can draw from your new accessories block, with the headlight on is 5A, not as you might think 10A (from the size of the fuse).
So you need to be a little careful what you plug into these sockets because the headlight is on all the time, day and night! Not forgetting that the current draw is cumulative, i.e. you add together all the currents required by all the accessories that you plug in at any one time to get the total current requirement. Under these circumstances it is really quite easy to pop a 10A fuse, especially as there is a significant surge current requirement when you first turn on your ignition. This means that when you turn the key the headlight appears as a dead short and draws a hefty spike of current to make the lamp glow. If you also have other stuff plugged in which also has surge currents then that is the moment when the fuse is most likely to blow. There is an old adage that says that a light bulb only blows when you turn it on and this is simply because of the surge current required to make an incandescent bulb glow white hot.
PS dont forget within tha calculation that the "V" actually when running is about 14 :whistle so the "I" may well be larger and the "P" therefore too, as ohm law dictates P=I^2 * R and the only constant really is the "R" of the lamp, so just be cautious when calculating total load of alternators :-(((
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Pardon me if I am wrong Diesel,.. I agree with the formula and calculation of current based on W=ExI (W = Watts, E = Volts and I = Amps), using a 60W globe in a 12V system hence 5A. If you're talking headlamps, don't forget to multiply by 2, which gives a total current draw on hi-beam of 10A based on your figures.
Relays are required to enable switching high current with a light (small) switch. It seems that you are just using the heavy cable as a feed to the fuse box and hence would not necessarily need a relay. That said, Brock is correct if you do want to switch power off when the bike isn't running. In that case you would need a minimum of a 35A relay.
The size fuse that you would put on the 30A cable depends on the overall anticipated current draw on the cable. If all devices fed by the cable have a combined max. current of 20A then a 25A fuse should be suitable. Your maximum constant current for that cable is obviously 30A in which case you go up to a 35A fuse to protect that cable if need be. Don't fit a fuse size that equals the anticipated maximum current draw as you may find yourself continually replacing fuses.
I don't think I can agree totally with Whizz's comments about surge currents etc. Headlights never equal a dead short as the electrical resistance always exists in the globe filament. The resistance may increase ever so slightly once the globe is illuminated but it is always there. A nominated Voltage can only push a limited amount of current through a set resistance. In this case, using nominal figures. a 12V globe pulling 5 Amp would have a resistance of around 2.4 Ohms by my electrical theory and calculations.
I am curious to know why Brock suggests that the relay should be powered from the tail light circuit. I would have thought any live, switched feed accessible would be acceptable.
Good advice too from Brock about checking on total capacity of your alternator v's total current required by accessories and the bike itself.
Cheers
Dennis
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why Brock suggests that the relay should be powered from the tail light circuit
I didnt say should, but could. The tail lights are easy to get at to pick up an ignition on detection. but any source is good. The P models are easy, as there are a couple of points in the wire cluster that are ready to go.
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Thanks Brock - here is some text I nicked from Whizz when commenting on Shiney's power socket installation:
Ohms Law says that Power equals Voltage multiplied by current, or P=V x I. This transposes to I=P/V or 60/12, so the headlight draws 5A when on high beam (4.58A on low beam). This means that the maximum current you can draw from your new accessories block, with the headlight on is 5A, not as you might think 10A (from the size of the fuse).
So you need to be a little careful what you plug into these sockets because the headlight is on all the time, day and night! Not forgetting that the current draw is cumulative, i.e. you add together all the currents required by all the accessories that you plug in at any one time to get the total current requirement. Under these circumstances it is really quite easy to pop a 10A fuse, especially as there is a significant surge current requirement when you first turn on your ignition. This means that when you turn the key the headlight appears as a dead short and draws a hefty spike of current to make the lamp glow. If you also have other stuff plugged in which also has surge currents then that is the moment when the fuse is most likely to blow. There is an old adage that says that a light bulb only blows when you turn it on and this is simply because of the surge current required to make an incandescent bulb glow white hot.
PS dont forget within tha calculation that the "V" actually when running is about 14 :whistle so the "I" may well be larger and the "P" therefore too, as ohm law dictates P=I^2 * R and the only constant really is the "R" of the lamp, so just be cautious when calculating total load of alternators :-(((
Buggar!!!,
Got my brain working now. When I was a jolly apprentice, Ohm's Law stated "The current flowing in any electrical circuit is directly proportional to the Voltage applied across that circuit and indirectly proportional to the resistance contained within the circuit". The basis is that an electrical circuit with 1 Ohm resistance and with 1 Volt applied will have a current of 1 amp flowing. Therefore if you increase the Voltage to 2 Volts, then 2 amps will flow. Conversely, if the resistance is doubled to 2 Ohm, then the current flow will halved to 0.5amp. (I=E/R)
Dale is right, if you work on the nominal voltage of 12 in your calcs, you will get one result, ie 5A for each headlamp on high beam. If you work with the maximum voltage for an alternator, potentially up to 14.6V then the current will be closer to 6.1A. Power will also increase proportionally though for the purposes of this discussion, current flow (I) is the important and overriding factor. You also need to consider that 12V is a nominal voltage only. A normal lead/acid automotive battery, fully charged, has a voltage closer to 13.2V hence an alternators voltage regulator will be set to 14 - 14.5V. Any higher and there is a risk of overheating the battery.
The brain hurts now.
Cheers
Dennis
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Thanks Brock - here is some text I nicked from Whizz when commenting on Shiney's power socket installation:
Ohms Law says that Power equals Voltage multiplied by current, or P=V x I. This transposes to I=P/V or 60/12, so the headlight draws 5A when on high beam (4.58A on low beam). This means that the maximum current you can draw from your new accessories block, with the headlight on is 5A, not as you might think 10A (from the size of the fuse).
So you need to be a little careful what you plug into these sockets because the headlight is on all the time, day and night! Not forgetting that the current draw is cumulative, i.e. you add together all the currents required by all the accessories that you plug in at any one time to get the total current requirement. Under these circumstances it is really quite easy to pop a 10A fuse, especially as there is a significant surge current requirement when you first turn on your ignition. This means that when you turn the key the headlight appears as a dead short and draws a hefty spike of current to make the lamp glow. If you also have other stuff plugged in which also has surge currents then that is the moment when the fuse is most likely to blow. There is an old adage that says that a light bulb only blows when you turn it on and this is simply because of the surge current required to make an incandescent bulb glow white hot.
PS dont forget within tha calculation that the "V" actually when running is about 14 :whistle so the "I" may well be larger and the "P" therefore too, as ohm law dictates P=I^2 * R and the only constant really is the "R" of the lamp, so just be cautious when calculating total load of alternators :-(((
Buggar!!!,
Got my brain working now. When I was a jolly apprentice, Ohm's Law stated "The current flowing in any electrical circuit is directly proportional to the Voltage applied across that circuit and indirectly proportional to the resistance contained within the circuit". The basis is that an electrical circuit with 1 Ohm resistance and with 1 Volt applied will have a current of 1 amp flowing. Therefore if you increase the Voltage to 2 Volts, then 2 amps will flow. Conversely, if the resistance is doubled to 2 Ohm, then the current flow will halved to 0.5amp. (I=E/R)
Dale is right, if you work on the nominal voltage of 12 in your calcs, you will get one result, ie 5A for each headlamp on high beam. If you work with the maximum voltage for an alternator, potentially up to 14.6V then the current will be closer to 6.1A. Power will also increase proportionally though for the purposes of this discussion, current flow is the important and overriding factor. You also need to consider that 12V is a nominal voltage only. A normal lead/acid automotive battery, fully charged, has a voltage closer to 13.2V hence an alternators voltage regulator will be 14 - 14.5V. Any higher and there is a risk of overheating the battery.
The brain hurts now.
Cheers
Dennis
Mine just flew a buse reading that
Tipsy
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Sorry Tipsy. Couldn't help myself!
Cheers
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Dale is right, if you work on the nominal voltage of 12 in your calcs, you will get one result, ie 5A for each headlamp on high beam. If you work with the maximum voltage for an alternator, potentially up to 14.6V then the current will be closer to 6.1A.
Hi Dennis - is the above why you'd give the system a little scope by putting, say, an 8A fuse in this example's circuit? (To allow for a little fluctuation)?
Cheers, Diesel
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Being in the dark about what is being powered by this circuit, if a HID light is in the circuit just remember that the maximum power it draws is much more on start up than on constant power (it spikes up when starting up, then goes back to a more consistent power use), so you have to allow for the start up spike in power draw in the wire and fuse requirement.
Allow for something like up to 30 to 50% extra amps required on power up compared to normal power on. If you are just powering halogen headlights or other power sources there is no such spike in power requirement. The ballasts should have some specifications on peak power draw and saturation power (ie when on all the time)
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That's the good thing about the HIDs, of course. One they're over the spike, their current draw is lower than their brightness suggests.
I noticed when I flicked my two 100w halogens on tonight the engine quit. :wink1
Well, not quite, but it certainly noticed a bit more work was required.
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Dale is right, if you work on the nominal voltage of 12 in your calcs, you will get one result, ie 5A for each headlamp on high beam. If you work with the maximum voltage for an alternator, potentially up to 14.6V then the current will be closer to 6.1A.
Hi Dennis - is the above why you'd give the system a little scope by putting, say, an 8A fuse in this example's circuit? (To allow for a little fluctuation)?
Thats right Diesel, Allow a little more that what the constant current draw will be. If you expect a constant current draw of 6, then an 8, or 10, amp fuse would be OK.
Remember that the fuse is there to protect the circuit in the event of damage, shorting and so forth and does nothing as long as all is working OK. A lead/acid battery can punch out 400 plus amps when there is little resistance so don't be too concerned about giving yourself some leeway. If anything goes wrong it won't take much to get 10amps flowing to cause the fuse to blow.
Another point to remember is to place the fuse as close as possible to the power source, ie the battery and make sure that the cable from the battery to the fuse is well protected.
Welcome to Tuesday
Dennis
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Thanks gentlemen - I was wondering how to run numerous 'switched' circuits if I pinched in to the tail light circuit. I thought that I'd overload the tail light circuit - but you've showed me that putting in a relay will draw next to no current, supply sufficient power for additional circuits, and give me the 'switched' power source I am after.
Thanks to all for a most helful and informative set of posts. :thumb
Cheers, Diesel
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Another happy customer!
What's obvious to the tech-heads is a revelation to the uninitiated. So everyone does their bit here.
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No Worries Diesel,
Hope it all works out for you.
Cheers
Dennis
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Here is my wiring diag for my switched fuse block set-up.....
Main relay is activated by switched power from tail light circuit (lower right hand corner of diagram).....
(http://i50.tinypic.com/5adsm.jpg)
This is what the sounds of angle grinders, crimpers, and soldering has been caused by that has been emanating from my garage this week. :grin
Quick math would suggest I need 15A fuses for the Halogens and HIDs - I haven't gotten that far yet with detail.
Cheers, Diesel
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Good job there :thumbsup The HID harnesses usually come with a 30amp fuse in them, but a 20amp should be fine, based on the maximum power draw during startup.
Very similar to what I have done. An extra I have is that the switched circuit - tail lights (I assume that is a relay?) can be turned off, so that the lights etc don't have to be going while the bike ignition is on.
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Guys, I'm not sure I understand the layout in the diagram supplied by Diesel. According to the diagram the 20A fuse feeds a fuse box via the tail light relay, two 10A fuses then feed a 40A relay each via a switch, and the relays then power either the headlights or the HID's. In this configuration the power for the headlights and the HID's is sourced from the fusebox, so exactly what are the two 40A relays doing? because as far as I can see the answer is nothing at all.
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The driving lights are no longer fed from the switched fuse box
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... According to the diagram the 20A fuse feeds a fuse box via the tail light relay, two 10A fuses then feed a 40A relay each via a switch, and the relays then power either the headlights or the HID's. In this configuration the power for the headlights and the HID's is sourced from the fusebox, so exactly what are the two 40A relays doing? because as far as I can see the answer is nothing at all.
My goal was to have (essentially) a 'switched' fuseable bus bar that could run a variety of items, and be neat, tidy and easily accessible. The HIDs have a built in relay (so nothing I can do there), and I am under the impression of not having a switch wired directly to the main load (Halogens), so I left the Relay that comes with the kit in line.
I am open to suggestions, but if I run the spotlights straight from the battery (through a fuse), a have to pinch in to a switched circuit anyway (the headlight hi-beam circuit) so I have drawn the diag a little wrong. I am trying to keep the wiring loom tidier through the bike frame and avoid having a spider web of earths and +ives going everywhere.
Is this better.....
(http://i45.tinypic.com/r8b6ea.jpg)
All suggestions welcome.
Cheers, Diesel
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A slightly modified diagram.
(http://img.photobucket.com/albums/v235/Avtrician/DieselsSwitchedpower.jpg)
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Thanks Brock, that makes far more sense. This uses the relays as they are supposed to be used, i.e. being controlled by a low current switch. Sorry to be pedantic Diesel but my job for the last 20+ years has been checking and approving electrical/electronic installation designs made by Grad Engineers for common sense (one of the least common commodities in the world it would appear) and workability, and the original drawing simply didn't look right. Brock has supplied the missing information for switching of the relays.
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.... Sorry to be pedantic Diesel but my job for the last 20+ years has been checking and approving electrical/electronic installation designs made by Grad Engineers for common sense ...
No probs Whizz - thanks for the input - this is why you are a great part of the brains trust around here. :thumbs
Now that Brock has hit 60.... yada yada yada.... :whistle :spank :-++
CHeers, Diesel
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Engineers for common sense
:eek :eek :eek :eek :eek
Isnt that a tautology, ie diametrically opposed ideas ?????
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That isn't Tautology which is defined as " (a) The saying of the same thing twice in different words, or (b) A phrase or expression in which the same thing is said twice in different words." However I was referring to the common sense levels of the designs not the Grads, and your prejudice is showing :grin
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I like the idea where Brock has the lights also switched through the main headlight (I thought this was a legal requirement?), however this appears to not allow for redundancy with lighting. Should the fuse for the driving lights fail then both sets are lost. (I understand that similarly the same could occur if the switched circuit fuse blew), however using the fuse block allows for one set of lights to be lost and still have the other set available?
In essence I would set mine similarly to how Brock has suggested but run the two sets of driving lights to separate fuses on the secondary fuse block and still have Diesel's separate switch for each set of driving light (thought this was a legal requirement as well?)
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The way I have mine set up is a common main power wire up to the front, protected by a fuse, then a fuse box that feeds power into each of the various circuits. The idea, as TJ says, it to have only one circuit go if that is the problem, rather than the main fuse taking everything out. Similar to how Honda set things up originally. My headlights can only come on with the ignition, and the driving lights only if the headlights are on high beam but this is optional through a switch.
I also have built in the ability to not have all those circuits on while the ignition is on. Main reason is so I can start the bike without stressing the HID headlights, but also so I can keep the ignition on without the bike running and use the autocom for the UHF and mobile without flattening the battery and having to take out the earplugs etc. This would have been handy one time in the dark to call ahead using the mobile through the Zumo to get a keysafe code from a caravan park without having the noise of the bike running and trying to tell the number to another rider to use on their phone then try and find a pen etc etc!. Also handy if you want to stop and contact someone via the UHF or mobile.
I also have the original headlight circuit in place so can put in H4 bulbs if necessary.
I am hoping that this built in redundancy is not necessary as I have not had a headlight or HID fuse go that caused a problem, but I am just allowing for contingencies based on past experience.
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While we are on interesting wiring ideas, and some professional elec types are watching, is there any technical difference or practical downside to using a switch controlling a relay to interrupt the ground feed as opposed to the switching power feed? I wired my most recent effort up to switch the ground on and off to the relay powering up the main power fuse box for the HID lights. My main reason was that is is probably less likely to cause problems with potential shorting out possibilities to have the ground wire switched than feed a live power feed through the switch. The less live wires routed around the bike the lesser the risk.
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As one of those professional types, (RAAF trained Avionics Tech) I will answer those questions.
Mechanically there is little difference between switching power, and switching earths.
With the aim of removing power wires, cant be done. You have to have a live feed to the item you are powering. You can place a fuse block close to your equipment, with a long single run to the battery and short leads to the load.
Switching power, applies power to the item from the switch to the load, allowing current to flow through the load and to earth. Turn off no power, and no flow.
Switching earth, allows the power at the load to supply current through to earth. Sounds the same doesnt it, but its not. The power is always there looking for a return path to ground. should the return (earth side) wear through, it could allow a good, or a poor (high resistance) path to ground, possibly causing heat, fire or drained battery, if its a hot item like a UHF wired directly to the battery. A stray earth (as it is called) will cause an item to be on wether you want it or not.
A worn through power wire will cause a short and blow the fuse.
It gets hard to explain this stuff, as I have been doing it for 40 yrs, and to me its inbuilt knowledge that can be hard to dig out.
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I makes sense to me.
The switched ground I am using is not a main power, but the switching power used to trigger the relay. There is already a fuse protecting the switching powered circuit (ie original Honda wiring). In my laymans logic, the power will try and find a return path to ground at the switch or later down the circuit at the relay if using switched power. By taking the power just to the relay, it will try and find ground there only. All depends on the circuit I suppose. I can always rewire it the other way around if that is better.
I found out it worked as I tried to reuse a 40A relay that was on the bike with the police wiring. First time I turned it on the main 30A fuse went as did the tailight fuse. Ditched that relay and works fine. At least I have a few new fuses on the bike!
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Earth switching for a relay is acceptable when going for a particular outcome. For example, the side stand switch mod to isolate the HID headlights when starting on the 1300 ( havent worked out one for the 1100, no one asked for it)
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That is probably the closest to what I am trying to achieve with the manual switch. Think of it as a sidestand down situation, except when the sidestand is not down.
Earth switching for a relay is acceptable when going for a particular outcome. For example, the side stand switch mod to isolate the HID headlights when starting on the 1300 ( havent worked out one for the 1100, no one asked for it)
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Think of it as a sidestand down situation, except when the sidestand is not down.
:eek :eek :eek :eek
I see you are really a gorgeous blonde then.. :rofl :rofl :crackup :crackup
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Almost all cars built in the last 10 or so years are switching the earth, I don't believe it is good practice as in the event of an accident a shorted earth cable can draw huge current through other devices and cause them to burn out,
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:rd13 :hatwave :runyay :think1
Winston66
I believe that Brock has it right.
My limited experience with automotive wiring tells me that in many automotive applications a switching ie. (activating)device of some sort be it either a relay or switch of some sort can be placed in the netural or otherwise earth return side of the circuit.That is between the device which has a positive feed to it and the its respective earthing point
It seems to me that this convention is done by the automotive people mainly to .
1 Sometimes simplify some of the complexity of some of the various circuits that they are trying to controll.Ie. the reversing motors that raise and or lower the car windows these motors can have seperately wound directional field windings which controll the rotational direction of the motor. Simarly some multi speed windscreen wiper motors have different earthing wires which are switched independatly in order to alter the motor speed .
2 Possibly to economise on the cost of the installation, I am not quite shure how though.
3 An attemt at confusing the average person who is generally taught that for electrical safety (ie. normal house hold 240 volt wiring and appliences , That the switch or isolating devices must be placed in the positive or as otherwise what is known as the active feed to the device or appliance.
Another thought that I have about fuses in automative situations is that their main purpose is to protect the wiring harness in the event of a catistrophic shorting out of the main current carrying wires to an un intended earthng point thus causing overheating and a possible destruction of the associated wiring. So therefore I generally do not try too hard to match the fuse to closley to the intended load and consequent current draw through the respective power feed, so in the main I will for instance put in a 10 amp fuse when I am working on an anticipated 5 amp draw. However as Brock says it is imperative that the fuse is placed as close to the start of the respective power feed as possible .
You know that it is all smoke and mirrors and it realy is majic stuff.
Cheers to all.
Winston 66 Northampton
:rd13 :thumbsup :runyay :think1 :beer
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I dont know of any cars these days that switch earths, gut I know that the Datsun 1600 did, gave me a headache at the time trying to get a mates driving light to work till I figured that out... :|||| :|||| :||||
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Whilst from a theoretical viewpoint the placement of the switch can be on either the live side or the neutral side of the device and it will work just fine, from a design viewpoint it is not correct to wire the switch on the neutral side. This is because if you switch off the device by breaking the neutral return, the device is still live and can be prone to seeking earth returns through any number of other devices. This does happen and parallel earthing can be a real bugger to find and fix. Switching the neutral side can be dangerous because of the possibility of short circuits causing systems to come on unexpectedly and can be disastrous in the case of an accident. In short, yes it is possible, but most definitely not recommended
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:beer Well, I was trying to keep it real simple for you
Think of it as a sidestand down situation, except when the sidestand is not down.
:eek :eek :eek :eek
I see you are really a gorgeous blonde then.. :rofl :rofl :crackup :crackup
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Yorkie, I'm not sure where you get the idea about cars switching the earth returns, I've not seen any that do unless, as Brock says, it's for a specific purpose.
Ever seen the result of someone removing the wrong battery terminal first, then welding the spanner to the frame in a huge shower of sparks? Because I have and it wasn't pretty!
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I suppose the other side of this is that the live wire if switched will be live at the switch, so also always seeking ground as well. So not much difference to being always live at the relay switch side or at a switch. For situations other than turning relays on or off, I can see that ground switching might not be the best idea.
Whilst from a theoretical viewpoint the placement of the switch can be on either the live side or the neutral side of the device and it will work just fine, from a design viewpoint it is not correct to wire the switch on the neutral side. This is because if you switch off the device by breaking the neutral return, the device is still live and can be prone to seeking earth returns through any number of other devices. This does happen and parallel earthing can be a real bugger to find and fix. Switching the neutral side can be dangerous because of the possibility of short circuits causing systems to come on unexpectedly and can be disastrous in the case of an accident. In short, yes it is possible, but most definitely not recommended
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:rd13 :thumbsup :runyay :think1
Winston66
Brock,
Think of the ecu in a car and for instance the coolant temperature detector in the block , a one wire device,this acts as a variable load in the respective earth circuit and is connected directly to the respective switching (monitoring)circuit in the ecu in order to controll the programme for the duty cycle of the fuel injectors when the coolant is cold and alters as the motor warms up ie the old fasioned choke controll for a cold motor start.
Also I believe tha many cars run an active loop around all of the courtesy lights and these are then switched on either individualy or otherwise as a group by being grounded by the actuation of the respective door switch earthing out when a door is opened.
Cheers to all
Winston66 Northampton
:rd13 :thumbsup :think1
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(Ever seen the result of someone removing the wrong battery terminal first, then welding the spanner to the frame in a huge shower of sparks? Because I have and it wasn't pretty!
[/quote]
As an apprentice I dropped a 1/4 drive socket bar into the electrical panel of a DC3 an although only 28volts, the amperage across the bar heated it to the point of melting the end off it. I learned some new words that day from the sparkys. :crackup
:bl11
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As Brock says, try wiring up driving lights on any Jap or Korean vehicle and the conventional way doesn't work because they are neg earth. I believe Australian manufacturers are going this way also, no idea why although Winston may have a point with what he says.
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Been negative earth for a bloody long time. Every vehicle I've ever owned or worked on has been neg earth, only old pommie stuff has the other way round, jap bikes have all been neg earth.
:bl11
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Im pretty sure that today every thing is -ve Earth, (+ve earth went out a long long time ago), and that most of the switching in cars is done with the positive line. Only a few things light courtesy glovebox and boot lights are earth switched.
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:wht11 py
Earth = what I walk on
grow veges in\
sometimes get covered in
Positive = Out riding with friends on our wonderful machines
Having a few stubbies at Home listening to music
Having a few drinks & BBQ with the Ostoc crowd
Negative = NOT HAVING ANY OF THE POSITVES
Tipsy
I could or not (relay) to this :p :p
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Tipsy, mate, what a wonderfully idyllic life you lead :beer :popcorn :hatwave :thumbs :rofl :crackup
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:crackup :crackup :beer :beer
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:rd13 :thumbsup :hatwave :runyay
winston66
Hey Tipsy,
You have the winning entry,
I will have a double drink on what you say.
Cheers Winston66, Northampton
:rd13 :|||| :-++ :hatwave :think1 :beer