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#21
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Starter solenoid current?
On 5/11/2011 11:16 PM, PeterD wrote:
> Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight, > etc.) any fuse is a luxury. Walmart? Harbor Freight? Surely you mean Bunnings or Repco -- Regards, Noddy. |
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#22
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Starter solenoid current?
On 11/5/2011 9:06 AM, Noddy wrote:
> On 5/11/2011 11:16 PM, PeterD wrote: > >> Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight, >> etc.) any fuse is a luxury. > > Walmart? Harbor Freight? > > Surely you mean Bunnings or Repco > Uh, sure... <bg> -- I'm never going to grow up. |
#23
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Starter solenoid current?
On Sat, 05 Nov 2011 16:28:04 -0400, PeterD > wrote:
>On 11/5/2011 9:06 AM, Noddy wrote: >> On 5/11/2011 11:16 PM, PeterD wrote: >> >>> Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight, >>> etc.) any fuse is a luxury. >> >> Walmart? Harbor Freight? >> >> Surely you mean Bunnings or Repco >> > >Uh, sure... <bg> Shouldn't you be waiting for some sucker to post in alt.marketing.online.ebay? I wonder how Lumpy is going... |
#24
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Starter solenoid current?
Paul Saccani > wrote:
>Bernd Felsche wrote: >>I also have a hand-held, digital 'scope. One of the clamp meters has >>peak-hold -- I'd forgotten about that. It might do the trick. >> >>Well, it'd tell me the current through the circuit. Which isn't >>necessarily the same current that'll be drawn when the long wire is >>replaced with a short one and a transistor switch. >...and now we get to what you are really up to. No doubt with a >MOSFET in mind. Don't neglect the back EMF, and the transient inrush >current could be significant. That's my main concern. The inrush and other transients. >You could always buy a COTS solid state relay - for you to engineer as >good a solution from parts for the hostile environment it can expect >to live in, is something that will cost you a good deal more than the >$23 for a COTS 80 A 0-100VDC solid state relay. BTS50055-1TMB is designed for the environment, provides useful feedback and therefore diagnostics (at about $6). I need to determine the solenoid current to allow for an adequate "overkill". -- /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia \ / ASCII ribbon campaign | For every complex problem there is an X against HTML mail | answer that is clear, simple, and wrong. / \ and postings | --HL Mencken |
#25
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Starter solenoid current?
Bernd Felsche > wrote:
>Paul Saccani > wrote: >>Bernd Felsche wrote: >>>Well, it'd tell me the current through the circuit. Which isn't >>>necessarily the same current that'll be drawn when the long wire is >>>replaced with a short one and a transistor switch. >>...and now we get to what you are really up to. No doubt with a >>MOSFET in mind. Don't neglect the back EMF, and the transient inrush >>current could be significant. >That's my main concern. The inrush and other transients. >>You could always buy a COTS solid state relay - for you to engineer as >>good a solution from parts for the hostile environment it can expect >>to live in, is something that will cost you a good deal more than the >>$23 for a COTS 80 A 0-100VDC solid state relay. >BTS50055-1TMB is designed for the environment, provides useful >feedback and therefore diagnostics (at about $6). I need to >determine the solenoid current to allow for an adequate "overkill". In retrospect (?), I can prototype just the power circuit to make sure that it doesn't release the magic smoke. Although testing would only be for the conditions under which I'm testing ... so need to make them as bad as possible. -- /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia \ / ASCII ribbon campaign | For every complex problem there is an X against HTML mail | answer that is clear, simple, and wrong. / \ and postings | --HL Mencken |
#26
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Starter solenoid current?
On 11/5/2011 4:54 PM, Jeßus wrote:
> On Sat, 05 Nov 2011 16:28:04 -0400, > wrote: > >> On 11/5/2011 9:06 AM, Noddy wrote: >>> On 5/11/2011 11:16 PM, PeterD wrote: >>> >>>> Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight, >>>> etc.) any fuse is a luxury. >>> >>> Walmart? Harbor Freight? >>> >>> Surely you mean Bunnings or Repco >>> >> >> Uh, sure...<bg> > > Shouldn't you be waiting for some sucker to post in > alt.marketing.online.ebay? I wonder how Lumpy is going... I see a bunch of posts there, so I suspect he's going balls to the wall! As for cheap DVOMs, I was in Harbor Freight the other day. The deal was spend a relatively nominal amount, and they gave you a free DVOM. So I got two! I tested their accuracy, it was OK (not great, but usable) so for the price a winner. -- I'm never going to grow up. |
#27
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Starter solenoid current?
Bernd Felsche > wrote:
>Paul Saccani > wrote: >>Bernd Felsche wrote: >>>I also have a hand-held, digital 'scope. One of the clamp meters has >>>peak-hold -- I'd forgotten about that. It might do the trick. >>>Well, it'd tell me the current through the circuit. Which isn't >>>necessarily the same current that'll be drawn when the long wire is >>>replaced with a short one and a transistor switch. >>...and now we get to what you are really up to. No doubt with a >>MOSFET in mind. Don't neglect the back EMF, and the transient inrush >>current could be significant. >That's my main concern. The inrush and other transients. >>You could always buy a COTS solid state relay - for you to engineer as >>good a solution from parts for the hostile environment it can expect >>to live in, is something that will cost you a good deal more than the >>$23 for a COTS 80 A 0-100VDC solid state relay. >BTS50055-1TMB is designed for the environment, provides useful >feedback and therefore diagnostics (at about $6). I need to >determine the solenoid current to allow for an adequate "overkill". The clamp meter shows just 5A peak in the solenoid. I suspect that's the average over about 0.1 seconds; which is about how long it takes to close the contacts that pull in the starter fully. The 5A is the highest peak out of about 20 (*) successive starts. I suspect that that's an average over the sampling period. Figures are scattered all over the place; from 0.3A up to 5A. Most in the 3 to 5A range. I'll have to put the digital scope with linear Hall-effect sensor on the wire to find the peak inrush current. (*) Don't want to cook the starter motor with too many successive starts without a reasonable cooling off period. -- /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia \ / ASCII ribbon campaign | For every complex problem there is an X against HTML mail | answer that is clear, simple, and wrong. / \ and postings | --HL Mencken |
#28
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Starter solenoid current?
On Sun, 20 Nov 2011 19:21:18 +0800, Bernd Felsche
> wrote: >The clamp meter shows just 5A peak in the solenoid. I suspect that's >the average over about 0.1 seconds; which is about how long it takes >to close the contacts that pull in the starter fully. > >The 5A is the highest peak out of about 20 (*) successive starts. I >suspect that that's an average over the sampling period. Figures >are scattered all over the place; from 0.3A up to 5A. Most in the 3 >to 5A range. You would be real lucky if the clampl meter had a sample rate as high as 10 Hz - many seem to have a sample rate of less than one per second! Cheers, Paul Saccani, Perth, Western Australia |
#29
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Starter solenoid current?
On Sat, 05 Nov 2011 10:41:58 +0800, Paul Saccani >
wrote: >On Fri, 4 Nov 2011 19:47:45 +1000, "Scotty" > >wrote: > >> >>I'd be VERY surprised if it was over 10 Amps to be honest. a 4 mm2 cable. >>Seeing as a 4mm cable is really only capable of 30 Amps for a reasonably >>short time. >> >>Id be testing with an ammeter. 90% of ammeters have internal fuses >>protecting the device anyway. > >That's a rather optimistic view of the effectiveness of the fuse. The >fuse is intended for personnel protection - they rarely protect the >meter from *high* currents - errant students demonstrate the art of >meter destruction to me at regular intervals. > >They often blow the tracks away before the fuse blows, sometimes even >the internal shunt goes before the fuse does. The PROPER fast blow instrument fuse IS there to protect the meter - and IS generally effective. Using a standard or slow blow fuse WILL fry the meter. NEVER replace the meter fuse with other than the proper quick-blow meter fuse. |
#30
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Starter solenoid current?
On Sun, 06 Nov 2011 17:47:51 +0800, Paul Saccani >
wrote: >On Sat, 05 Nov 2011 08:16:49 -0400, PeterD > wrote: > >>> >>> There should be HRC fuses in meters. They should blow well before the >>> tracks, should that is, >> >>Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight, >>etc.) any fuse is a luxury. > >Besides us not being merkins, the fuse is there to protect you more >than the meter. Nope. Unless they work different when they are upside-down, and I didn't notice that effect in Livingstone. |
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