10-06-2006, 05:58 PM
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Junior Member
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Join Date: Jul 2003
Posts: 130
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Which starter to buy?
On Fri, 06 Oct 2006 00:59:01 -0400, Steve T <fotocord@yahoo.com>
wrote:
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metoo wrote:
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On Thu, 05 Oct 2006 01:29:29 -0400, Steve T <fotocord@yahoo.com> wrote:
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metoo wrote:> On Wed, 04 Oct 2006 00:07:22 -0400, Steve T <fotocord@yahoo.com>> wrote:>>>metoo wrote:>>>>> simple E=I*R>>>>>> I=E/R>>>>>> 12 volts devided by 400,000 ohms ( I just measured between indexfinge>>> and thumb on one hand to indexfinger and thumb on other hand, squeezed>>> hard lowest reading i saw was about 4000,000 ohms) = .03 millamps. Not>>> enough to feel.>>>>>> Touch the main terminal of the starter with 1 hand on the frame and>>> you will not feel anything when someone cranks the car UNTILL they>>> release the key and the counter EMF (caused by the magnetic lines of>>> flux collapsing) will produce hundreds or thousands of volts at low>>> current will shock the hell out of you because then 4000 volts devided>>> by 400,000 ohms will allow 10 millamps to go thru you and that sir>>> could be lethal!!>>>>>>>When you let off the key, the solenoid disengages, so any EMF wouldn't>>transfer to the post being held.>> the solenoid disengaging is what causes the counter-EMF The magnetic> flux being developed by the coil all of a sudden have no where to go> so they collapse back to the coil. With no return path to ground.> the very high resistance makes the voltage so high at the post. Basic> electronics.> The solenoid is a relay. When you disengage it, any EMF would NOT dischargeto the positive post on the solenoid the battery cable connects to, thecoil isn't connected to that post! There might be some voltage at thetrigger wire but the low ohms of a solenoid coil (go measure one) isn'tgoing to create a high voltage spike that would cause a severe shock likean ignition coil is going to. Basic electronics..
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Ok you got me. I do remember using the master key ( Any metal that you can find, wire, screwdriver, key,etc) more then once to energize the solenoid and get it started. many times I remember a hell of a shock.
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Hmm I think I would stop doing something that gave me a hell of a shockafter the first time it happened, but hey that's just me...
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HMM I have always felt a need to charge up every once in a while It
keeps me from being stupid like you
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You made me think about it because you are right. Next time I do it I will be sure to take the screwdriver off the solenoid before I take it off the hot post and that should allow me to avoid the hi voltage of the counter-emf. However I still disagree with you about the high voltage spike. without going into a lot of detail ( I have been employed in the electronic field since 67 and earned my BSEE in 73) I will just remind you that the dc resistance of that ignition coil is also very low.
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But there isn't large voltage created on the low ohm side is there? Thehigh voltage is created on the high ohm side of the coil.
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You better read up Google is your friend, I don't need to tell you
again, you just want to argue!
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I would take a bet that I could measure at least 1000 volts within .5 milliseconds of the collapse of the magnetic field in most solenoids
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I have no idea but is seems if this was true, you'd have a major problemwith this voltage spike being sent back to the ignition switch and quicklyburning them or the starter relay up if this was the case. 1000 volts isgoing to jump across relay points in free air and they sure wouldn't lastvery long.
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maybe that is way we put damping diodes and capacitors across relay
coils.
But that voltage is there and you can do something about it if you
want to. lots of designs don't do anything about it.
You better read up Google is your friend, I don't need to tell you
again, you just want to argue!
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10-06-2006, 10:03 PM
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Junior Member
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Join Date: Jan 2004
Posts: 748
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Which starter to buy?
metoo wrote:
Quote:
On Fri, 06 Oct 2006 00:59:01 -0400, Steve T <fotocord@yahoo.com> wrote:
I do remember using the master key ( Any metal that you can find, wire, screwdriver, key,etc) more then once to energize the solenoid and get it started. many times I remember a hell of a shock.Hmm I think I would stop doing something that gave me a hell of a shockafter the first time it happened, but hey that's just me... HMM I have always felt a need to charge up every once in a while It keeps me from being stupid like you
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OK let's see, you repeatedly gave yourself a "hell of a shock" doing the
same thing over and over many times and then call me stupid? How many
times did it take for you to figure out not to put your hand on a red hot
cooktop eye?
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You made me think about it because you are right. Next time I do it I will be sure to take the screwdriver off the solenoid before I take it off the hot post and that should allow me to avoid the hi voltage of the counter-emf. However I still disagree with you about the high voltage spike. without going into a lot of detail ( I have been employed in the electronic field since 67 and earned my BSEE in 73) I will just remind you that the dc resistance of that ignition coil is also very low.
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But there isn't large voltage created on the low ohm side is there? Thehigh voltage is created on the high ohm side of the coil. You better read up Google is your friend, I don't need to tell you again, you just want to argue!
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Maybe you should research what the secondary side of the ignition coil is
made for. Hint: it's to create the high voltage that can shock you. Hint 2:
A starter solenoid doesn't have a secondary winding.
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I would take a bet that I could measure at least 1000 volts within .5 milliseconds of the collapse of the magnetic field in most solenoids
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I have no idea but is seems if this was true, you'd have a major problemwith this voltage spike being sent back to the ignition switch and quicklyburning them or the starter relay up if this was the case. 1000 volts isgoing to jump across relay points in free air and they sure wouldn't lastvery long. maybe that is way we put damping diodes and capacitors across relay coils.
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That is to protect sensitive electronics that can be damaged from MINUTE
current flow at anything over their base voltage. Doesn't mean these can be
felt by a human (they can't) much less kill them.
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But that voltage is there and you can do something about it if you want to. lots of designs don't do anything about it.
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If there was a thousand volts at a high enough current to kill a human, it
would fry a starter relay or switch in a VERY short period of time.
--
Steve
http://www.atlantaracing.com
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10-07-2006, 12:41 AM
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Junior Member
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Join Date: Jul 2003
Posts: 130
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Which starter to buy?
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10-07-2006, 10:09 PM
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Junior Member
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Join Date: Jul 2006
Posts: 48
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Which starter to buy?
Come on guys, let's not make this a pissing contest. We can disagree
and respect eachother's position even if we think it is stupid. I
never stop learning and always keep an open mind, but hell, it is just
stupid me
metoo wrote:
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