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Discussion Starter · #21 ·
I believe you can get one of these from KTA and or Electro Automotive.

---- dave cover <[email protected]> wrote:
> Along the same vein, I picked up a shunt for the motor side of my
> controller, 50mv/1000Amps. I wanted to measure the current my controller
> could handle and came across a shunt first. I had been watching for a lon g
> time before this option came along. The problem I'm finding is no one makes
> a meter to match the shunt.
>
> I've been watching eBay as well as the usual sources; DigiKey, Mouser,
> SurplusStore, etc. I just can't find a compatible meter. I'd even go with a
> 50mv/100A meter, but haven't seen one. It seems all the meters in my range
> work at 75mv for the top end.
>
> Since you already have a meter, you know what shunt you need. My problem is
> I can't find a meter to match my shunt. Go figure. If I'd have known how
> incompatible these can be I wouldn't have jumped on it so quickly.
>
> Dave Cover
>
>
Zeke Yewdall <[email protected]> wrote:
>
> > I've only seen ones that are 50mV/500A and 100mV/100A (Occasionally
> > 100mV/150A or 50mV/100A). I suppose you could use two of the
> > 50mV/500A shunts in series, then put a 3:4 voltage divider on the
> > signal to generate the 75mV/500A signal.... sort of clunky though...
> >
> > Z
> >
> > On Mon, Apr 28, 2008 at 5:39 AM, vehiculeselectriques.free.fr
> > <[email protected]> wrote:
> > > Mine is more like this one, though for a 75mV/500A,
> > > If your customer is in a hurry, i'm willing to sell it as i never
> > ordered
> > > the Emeter to use it with, contact me off list
> > >
> > >
> > http://cgi.ebay.com/Blue-Sea-9229-Analog-Meter-Shunt-75A-50mV_W0QQitemZ120231828390QQihZ002QQcategoryZ58049QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
> > >
> > >
> > > philippe
> > >
> > > 2008/4/28, Ian Hooper <[email protected]>:
> > > >
> > >
> > >
> > > > Yeah that's the exact sort he's not happy with - apparently they are
> > > > too big, too ugly (roughly finished), and too hard to mount (no
> > > > insulating base). He's actually not the first of my customers to
> > > > complain about these shunts either, oh well..
> > > >
> > > > -Ian
> > > >
> > > > On 28/04/2008, at 6:04 PM, [email protected] wrote:
> > > >
> > > > >> they appears on Ebay often, i have purchased mine from here
> > > > >>
> > > > >> Philippe
> > > > >
> > > > > If he has one like this:
> > > > > http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250241133623
> > > > > they look neat enough. Would be nice to have a non-conductive block
> > > > > attached at the bottom for mounting, or how about a clear tube
> > > > > (http://electroauto.com/catalog/elec.shtml#fuselink) to protect
> > from
> > > > > contact?
> > > > >
> > > > > _______________________________________________
> > > > > For subscription options, see
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> > > > >
> > > >
> > > > _______________________________________________
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> > > >
> > > _______________________________________________
> > > For subscription options, see
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> > >
> >
> > _______________________________________________
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> >
> _______________________________________________
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Discussion Starter · #22 ·
Ah, I didn't even consider the possibility of it being an analog
meter. I just assumed it was an e-meter/link10 type device. Ooops.

I don't think the resistor bridge will work to increase the voltage --
if we wanted a lower signal voltage than what the shunt is giving, we
could use it to decrease the voltage though. Any other EE's want to
weigh in on this?

Z

Mark Grasser <[email protected]> wrote:
> I think if it is analog Lee 1s correct, 1/3 the resistance of the meter in
> series will the meter should do it. It's volts at this point not amps, the
> current will be very low. If it is a digital meter then a resistor bridge of
> two resistors will do. Something like 100 ohms and 33 ohms in series across
> the shunt and then the meter across the 100 ohm resistor.
>
> Mark Grasser
>
>
>
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf
> Of Zeke Yewdall
> Sent: Monday, April 28, 2008 11:49 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Shunts
>
> >
> > The easiest solution is to get a 100mv shunt, and connect a resistor in
> > series with the meter to drop the extra 25mv (so he gets 75mv at the
> meter).
> >
>
> That's pretty tricky, since you'd have to know exactly how much
> current the meter was drawing. I'm not familiar with the particular
> one he has, but the ones I've used are very low current -- like
> microamps, on the sense inputs. If the meter doesn't have seperate
> sense and power inputs, the current draw could be up in the mA range,
> but could also vary depending on how many digits of the display are
> lit up, which won't work.
>
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
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> http://lists.sjsu.edu/mailman/listinfo/ev
>

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Discussion Starter · #23 ·
Zeke Yewdall <[email protected]> wrote:
> Ah, I didn't even consider the possibility of it being an analog
> meter. I just assumed it was an e-meter/link10 type device. Ooops.
>
> I don't think the resistor bridge will work to increase the voltage --
> if we wanted a lower signal voltage than what the shunt is giving, we
> could use it to decrease the voltage though. Any other EE's want to
> weigh in on this?

I guess this also depends on which question we are answering... there
are now two of them running through this thread. :)

>
> Z
>
>
>
> On Mon, Apr 28, 2008 at 10:22 AM, Mark Grasser <[email protected]> wrote:
> > I think if it is analog Lee 1s correct, 1/3 the resistance of the meter in
> > series will the meter should do it. It's volts at this point not amps, the
> > current will be very low. If it is a digital meter then a resistor bridge of
> > two resistors will do. Something like 100 ohms and 33 ohms in series across
> > the shunt and then the meter across the 100 ohm resistor.
> >
> > Mark Grasser
> >
> >
> >
> >
> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]] On Behalf
> > Of Zeke Yewdall
> > Sent: Monday, April 28, 2008 11:49 AM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] Shunts
> >
> > >
> > > The easiest solution is to get a 100mv shunt, and connect a resistor in
> > > series with the meter to drop the extra 25mv (so he gets 75mv at the
> > meter).
> > >
> >
> > That's pretty tricky, since you'd have to know exactly how much
> > current the meter was drawing. I'm not familiar with the particular
> > one he has, but the ones I've used are very low current -- like
> > microamps, on the sense inputs. If the meter doesn't have seperate
> > sense and power inputs, the current draw could be up in the mA range,
> > but could also vary depending on how many digits of the display are
> > lit up, which won't work.
> >
> >
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>

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Discussion Starter · #24 ·
I was responding to the question of how to use a 100mv shunt with a 75mv
meter. Either resistor method should work. The only way to use the 50mv
shunt would be to use some type of amplifier circuit. Incidentally, 1000amps
= a .1volt drop across the 100mvshunt. That 100 watts of heat. You will need
to be moving some air if you are going to do it very often.

Mark Grasser



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Zeke Yewdall
Sent: Monday, April 28, 2008 1:01 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Shunts

Zeke Yewdall <[email protected]> wrote:
> Ah, I didn't even consider the possibility of it being an analog
> meter. I just assumed it was an e-meter/link10 type device. Ooops.
>
> I don't think the resistor bridge will work to increase the voltage --
> if we wanted a lower signal voltage than what the shunt is giving, we
> could use it to decrease the voltage though. Any other EE's want to
> weigh in on this?

I guess this also depends on which question we are answering... there
are now two of them running through this thread. :)

>
> Z
>
>
>
> On Mon, Apr 28, 2008 at 10:22 AM, Mark Grasser <[email protected]>
wrote:
> > I think if it is analog Lee 1s correct, 1/3 the resistance of the meter
in
> > series will the meter should do it. It's volts at this point not amps,
the
> > current will be very low. If it is a digital meter then a resistor
bridge of
> > two resistors will do. Something like 100 ohms and 33 ohms in series
across
> > the shunt and then the meter across the 100 ohm resistor.
> >
> > Mark Grasser
> >
> >
> >
> >
> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]] On
Behalf
> > Of Zeke Yewdall
> > Sent: Monday, April 28, 2008 11:49 AM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] Shunts
> >
> > >
> > > The easiest solution is to get a 100mv shunt, and connect a
resistor in
> > > series with the meter to drop the extra 25mv (so he gets 75mv at
the
> > meter).
> > >
> >
> > That's pretty tricky, since you'd have to know exactly how much
> > current the meter was drawing. I'm not familiar with the particular
> > one he has, but the ones I've used are very low current -- like
> > microamps, on the sense inputs. If the meter doesn't have seperate
> > sense and power inputs, the current draw could be up in the mA range,
> > but could also vary depending on how many digits of the display are
> > lit up, which won't work.
> >
> >
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>

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Discussion Starter · #25 ·
Okay. We agree :) I thought you were referring to the 50mV shunt.

yeah... that's alot of heat for a little shunt to dissipate. I've
never actually seen a shunt rated at any more than 500 amps, and those
are 50mV ones, so only 25 wattts there. But, apparently there are
bigger ones out there.

Z

Mark Grasser <[email protected]> wrote:
> I was responding to the question of how to use a 100mv shunt with a 75mv
> meter. Either resistor method should work. The only way to use the 50mv
> shunt would be to use some type of amplifier circuit. Incidentally, 1000amps
> = a .1volt drop across the 100mvshunt. That 100 watts of heat. You will need
> to be moving some air if you are going to do it very often.
>
>
> Mark Grasser
>
>
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf
> Of Zeke Yewdall
>
>
> Sent: Monday, April 28, 2008 1:01 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Shunts
>
> On Mon, Apr 28, 2008 at 10:59 AM, Zeke Yewdall <[email protected]> wrote:
> > Ah, I didn't even consider the possibility of it being an analog
> > meter. I just assumed it was an e-meter/link10 type device. Ooops.
> >
> > I don't think the resistor bridge will work to increase the voltage --
> > if we wanted a lower signal voltage than what the shunt is giving, we
> > could use it to decrease the voltage though. Any other EE's want to
> > weigh in on this?
>
> I guess this also depends on which question we are answering... there
> are now two of them running through this thread. :)
>
> >
> > Z
> >
> >
> >
> > On Mon, Apr 28, 2008 at 10:22 AM, Mark Grasser <[email protected]>
> wrote:
> > > I think if it is analog Lee 1s correct, 1/3 the resistance of the meter
> in
> > > series will the meter should do it. It's volts at this point not amps,
> the
> > > current will be very low. If it is a digital meter then a resistor
> bridge of
> > > two resistors will do. Something like 100 ohms and 33 ohms in series
> across
> > > the shunt and then the meter across the 100 ohm resistor.
> > >
> > > Mark Grasser
> > >
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: [email protected] [mailto:[email protected]] On
> Behalf
> > > Of Zeke Yewdall
> > > Sent: Monday, April 28, 2008 11:49 AM
> > > To: Electric Vehicle Discussion List
> > > Subject: Re: [EVDL] Shunts
> > >
> > > >
> > > > The easiest solution is to get a 100mv shunt, and connect a
> resistor in
> > > > series with the meter to drop the extra 25mv (so he gets 75mv at
> the
> > > meter).
> > > >
> > >
> > > That's pretty tricky, since you'd have to know exactly how much
> > > current the meter was drawing. I'm not familiar with the particular
> > > one he has, but the ones I've used are very low current -- like
> > > microamps, on the sense inputs. If the meter doesn't have seperate
> > > sense and power inputs, the current draw could be up in the mA range,
> > > but could also vary depending on how many digits of the display are
> > > lit up, which won't work.
> > >
> > >
> > >
> > > _______________________________________________
> > > For subscription options, see
> > > http://lists.sjsu.edu/mailman/listinfo/ev
> > >
> > > _______________________________________________
> > > For subscription options, see
> > > http://lists.sjsu.edu/mailman/listinfo/ev
> > >
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

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Discussion Starter · #26 ·
I talked to a representative of a shunt company, and he said that the
rating listed on the shunt is the *continuous* rating, and they should
be able to handle much more peak current.

-Morgan LaMoore

Zeke Yewdall <[email protected]> wrote:
> Okay. We agree :) I thought you were referring to the 50mV shunt.
>
> yeah... that's alot of heat for a little shunt to dissipate. I've
> never actually seen a shunt rated at any more than 500 amps, and those
> are 50mV ones, so only 25 wattts there. But, apparently there are
> bigger ones out there.
>
> Z
>
>
>
> On Mon, Apr 28, 2008 at 11:40 AM, Mark Grasser <[email protected]> wrote:
> > I was responding to the question of how to use a 100mv shunt with a 75mv
> > meter. Either resistor method should work. The only way to use the 50mv
> > shunt would be to use some type of amplifier circuit. Incidentally, 1000amps
> > = a .1volt drop across the 100mvshunt. That 100 watts of heat. You will need
> > to be moving some air if you are going to do it very often.
> >
> >
> > Mark Grasser
> >
> >
> >
> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]] On Behalf
> > Of Zeke Yewdall
> >
> >
> > Sent: Monday, April 28, 2008 1:01 PM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] Shunts
> >
> > On Mon, Apr 28, 2008 at 10:59 AM, Zeke Yewdall <[email protected]> wrote:
> > > Ah, I didn't even consider the possibility of it being an analog
> > > meter. I just assumed it was an e-meter/link10 type device. Ooops.
> > >
> > > I don't think the resistor bridge will work to increase the voltage --
> > > if we wanted a lower signal voltage than what the shunt is giving, we
> > > could use it to decrease the voltage though. Any other EE's want to
> > > weigh in on this?
> >
> > I guess this also depends on which question we are answering... there
> > are now two of them running through this thread. :)
> >
> > >
> > > Z
> > >
> > >
> > >
> > > On Mon, Apr 28, 2008 at 10:22 AM, Mark Grasser <[email protected]>
> > wrote:
> > > > I think if it is analog Lee 1s correct, 1/3 the resistance of the meter
> > in
> > > > series will the meter should do it. It's volts at this point not amps,
> > the
> > > > current will be very low. If it is a digital meter then a resistor
> > bridge of
> > > > two resistors will do. Something like 100 ohms and 33 ohms in series
> > across
> > > > the shunt and then the meter across the 100 ohm resistor.
> > > >
> > > > Mark Grasser
> > > >
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: [email protected] [mailto:[email protected]] On
> > Behalf
> > > > Of Zeke Yewdall
> > > > Sent: Monday, April 28, 2008 11:49 AM
> > > > To: Electric Vehicle Discussion List
> > > > Subject: Re: [EVDL] Shunts
> > > >
> > > > >
> > > > > The easiest solution is to get a 100mv shunt, and connect a
> > resistor in
> > > > > series with the meter to drop the extra 25mv (so he gets 75mv at
> > the
> > > > meter).
> > > > >
> > > >
> > > > That's pretty tricky, since you'd have to know exactly how much
> > > > current the meter was drawing. I'm not familiar with the particular
> > > > one he has, but the ones I've used are very low current -- like
> > > > microamps, on the sense inputs. If the meter doesn't have seperate
> > > > sense and power inputs, the current draw could be up in the mA range,
> > > > but could also vary depending on how many digits of the display are
> > > > lit up, which won't work.
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > For subscription options, see
> > > > http://lists.sjsu.edu/mailman/listinfo/ev
> > > >
> > > > _______________________________________________
> > > > For subscription options, see
> > > > http://lists.sjsu.edu/mailman/listinfo/ev
> > > >
> > >
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

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Discussion Starter · #27 ·
Maybe his shunts, depends how they rate them. I have melted the solder out
of shunts, turned them blue, even made them blister, never more than 25%
over the rating. Of course the ones I used came from "that place".

Mark Grasser
Balyntec
Marine Products, LLC
828-581-4601
[email protected]


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Morgan LaMoore
Sent: Monday, April 28, 2008 2:11 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Shunts

I talked to a representative of a shunt company, and he said that the
rating listed on the shunt is the *continuous* rating, and they should
be able to handle much more peak current.

-Morgan LaMoore

Zeke Yewdall <[email protected]> wrote:
> Okay. We agree :) I thought you were referring to the 50mV shunt.
>
> yeah... that's alot of heat for a little shunt to dissipate. I've
> never actually seen a shunt rated at any more than 500 amps, and those
> are 50mV ones, so only 25 wattts there. But, apparently there are
> bigger ones out there.
>
> Z
>
>
>
> On Mon, Apr 28, 2008 at 11:40 AM, Mark Grasser <[email protected]>
wrote:
> > I was responding to the question of how to use a 100mv shunt with a
75mv
> > meter. Either resistor method should work. The only way to use the
50mv
> > shunt would be to use some type of amplifier circuit. Incidentally,
1000amps
> > = a .1volt drop across the 100mvshunt. That 100 watts of heat. You
will need
> > to be moving some air if you are going to do it very often.
> >
> >
> > Mark Grasser
> >
> >
> >
> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]] On
Behalf
> > Of Zeke Yewdall
> >
> >
> > Sent: Monday, April 28, 2008 1:01 PM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] Shunts
> >
> > On Mon, Apr 28, 2008 at 10:59 AM, Zeke Yewdall <[email protected]>
wrote:
> > > Ah, I didn't even consider the possibility of it being an analog
> > > meter. I just assumed it was an e-meter/link10 type device.
Ooops.
> > >
> > > I don't think the resistor bridge will work to increase the voltage
--
> > > if we wanted a lower signal voltage than what the shunt is giving,
we
> > > could use it to decrease the voltage though. Any other EE's want
to
> > > weigh in on this?
> >
> > I guess this also depends on which question we are answering... there
> > are now two of them running through this thread. :)
> >
> > >
> > > Z
> > >
> > >
> > >
> > > On Mon, Apr 28, 2008 at 10:22 AM, Mark Grasser
<[email protected]>
> > wrote:
> > > > I think if it is analog Lee 1s correct, 1/3 the resistance of the
meter
> > in
> > > > series will the meter should do it. It's volts at this point not
amps,
> > the
> > > > current will be very low. If it is a digital meter then a
resistor
> > bridge of
> > > > two resistors will do. Something like 100 ohms and 33 ohms in
series
> > across
> > > > the shunt and then the meter across the 100 ohm resistor.
> > > >
> > > > Mark Grasser
> > > >
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: [email protected]
[mailto:[email protected]] On
> > Behalf
> > > > Of Zeke Yewdall
> > > > Sent: Monday, April 28, 2008 11:49 AM
> > > > To: Electric Vehicle Discussion List
> > > > Subject: Re: [EVDL] Shunts
> > > >
> > > > >
> > > > > The easiest solution is to get a 100mv shunt, and connect a
> > resistor in
> > > > > series with the meter to drop the extra 25mv (so he gets 75mv
at
> > the
> > > > meter).
> > > > >
> > > >
> > > > That's pretty tricky, since you'd have to know exactly how much
> > > > current the meter was drawing. I'm not familiar with the
particular
> > > > one he has, but the ones I've used are very low current -- like
> > > > microamps, on the sense inputs. If the meter doesn't have
seperate
> > > > sense and power inputs, the current draw could be up in the mA
range,
> > > > but could also vary depending on how many digits of the display
are
> > > > lit up, which won't work.
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > For subscription options, see
> > > > http://lists.sjsu.edu/mailman/listinfo/ev
> > > >
> > > > _______________________________________________
> > > > For subscription options, see
> > > > http://lists.sjsu.edu/mailman/listinfo/ev
> > > >
> > >
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
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70 Posts
Discussion Starter · #28 ·
Take a look at this 100A meter (you have to multiply by 10):

http://www.allelectronics.com/cgi-bin/item/PMD-100A/385/100_AMP_DC_PANEL_METER_.html

They don't say how many mV it is, but they also sell a 100A 50mV shunt,
so my guess is...

- SteveS

Zeke Yewdall wrote:
> You could always use a standard 50mV/500A meter, and remember that
> it's only reading half of the actual amperage......
>
> Z
>
>
dave cover <[email protected]> wrote:
>
>> Along the same vein, I picked up a shunt for the motor side of my
>> controller, 50mv/1000Amps. I wanted to measure the current my controller
>> could handle and came across a shunt first. I had been watching for a lon g
>> time before this option came along. The problem I'm finding is no one makes
>> a meter to match the shunt.
>>
>> I've been watching eBay as well as the usual sources; DigiKey, Mouser,
>> SurplusStore, etc. I just can't find a compatible meter. I'd even go with a
>> 50mv/100A meter, but haven't seen one. It seems all the meters in my range
>> work at 75mv for the top end.
>>
>> Since you already have a meter, you know what shunt you need. My problem is
>> I can't find a meter to match my shunt. Go figure. If I'd have known how
>> incompatible these can be I wouldn't have jumped on it so quickly.
>>
>> Dave Cover
>>
>>
>>
>> On Mon, Apr 28, 2008 at 9:18 AM, Zeke Yewdall <[email protected]> wrote:
>>
>> > I've only seen ones that are 50mV/500A and 100mV/100A (Occasionally
>> > 100mV/150A or 50mV/100A). I suppose you could use two of the
>> > 50mV/500A shunts in series, then put a 3:4 voltage divider on the
>> > signal to generate the 75mV/500A signal.... sort of clunky though...
>> >
>> > Z
>> >
>> > On Mon, Apr 28, 2008 at 5:39 AM, vehiculeselectriques.free.fr
>> > <[email protected]> wrote:
>> > > Mine is more like this one, though for a 75mV/500A,
>> > > If your customer is in a hurry, i'm willing to sell it as i never
>> > ordered
>> > > the Emeter to use it with, contact me off list
>> > >
>> > >
>> > http://cgi.ebay.com/Blue-Sea-9229-Analog-Meter-Shunt-75A-50mV_W0QQitemZ120231828390QQihZ002QQcategoryZ58049QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
>> > >
>> > >
>> > > philippe
>> > >
>> > > 2008/4/28, Ian Hooper <[email protected]>:
>> > > >
>> > >
>> > >
>> > > > Yeah that's the exact sort he's not happy with - apparently they are
>> > > > too big, too ugly (roughly finished), and too hard to mount (no
>> > > > insulating base). He's actually not the first of my customers to
>> > > > complain about these shunts either, oh well..
>> > > >
>> > > > -Ian
>> > > >
>> > > > On 28/04/2008, at 6:04 PM, [email protected] wrote:
>> > > >
>> > > > >> they appears on Ebay often, i have purchased mine from here
>> > > > >>
>> > > > >> Philippe
>> > > > >
>> > > > > If he has one like this:
>> > > > > http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250241133623
>> > > > > they look neat enough. Would be nice to have a non-conductive block
>> > > > > attached at the bottom for mounting, or how about a clear tube
>> > > > > (http://electroauto.com/catalog/elec.shtml#fuselink) to protect
>> > from
>> > > > > contact?
>>
>
>

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Discussion Starter · #29 ·
dave cover wrote:
> Along the same vein, I picked up a shunt for the motor side of my
> controller, 50mv/1000Amps. I wanted to measure the current my controller
> could handle and came across a shunt first. I had been watching for a lon g
> time before this option came along. The problem I'm finding is no one makes
> a meter to match the shunt.
>
> I've been watching eBay as well as the usual sources; DigiKey, Mouser,
> SurplusStore, etc. I just can't find a compatible meter. I'd even go with a
> 50mv/100A meter, but haven't seen one. It seems all the meters in my range
> work at 75mv for the top end.
>
> Since you already have a meter, you know what shunt you need. My problem is
> I can't find a meter to match my shunt. Go figure. If I'd have known how
> incompatible these can be I wouldn't have jumped on it so quickly.

50mv is a common standard shunt values. You know, you can just *buy* a
meter to match, without getting it surplus or used. Digikey and Mouser
specialize in electronics, not electrics like meters, so they aren't a
preferres source.

Try Simpson Electric Co. at http://www.simpsonelectric.com/ and look at
their analog panel meters.

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Discussion Starter · #30 ·
>> The easiest solution is to get a 100mv shunt, and connect a
>> resistor in series with the meter to drop the extra 25mv (so he
>> gets 75mv at the meter).

Zeke Yewdall wrote:
> That's pretty tricky, since you'd have to know exactly how much
> current the meter was drawing.

Analog ammeters are just a simple resistor electrically. Often, their
resistance is printed right on them. An analog ammeter marked (say) "100
amps" will in fact be a 50 millivolt full-scale meter that draws between
1 ma and 100 ma. For example, I have one with a "50 amp" scale; it's
actually 50mv full-scale and measures 18 ohms (2.77ma full scale). To
use it with a 75mv shunt, add a 9 ohm precision resistor in series.

Digital meters often have a very high input impedance (1 megohm or
more). For example, the common E-meter / Link-10 is 2 megohms input
impedance. So a simple voltage divider will work fine.

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Discussion Starter · #31 ·
Morgan LaMoore wrote:

> I talked to a representative of a shunt company, and he said
> that the rating listed on the shunt is the *continuous*
> rating, and they should be able to handle much more peak current.

Be aware that this will apparently depend on whose shunt you are using (and=
perhaps even on the technical knowledge of the representative you speak wi=
th ;^). Deltec shunts, for instance are not to be used at more than 2/3 of=
the rated current continuously. Fromt the Deltec website (<http://www.del=
tecco.com/>):

"Shunt Operation
For continuous operation, it is recommended that shunts are not used at mor=
e than 2/3 of the rated current under normal operation conditions. Shunts s=
hould be located in an area where freely circulating air is available. If t=
his is not possible adequate forced ventilation should be provided to keep =
the shunt operating temperature at 40=B0 - 60=B0C. Shunt temperature must b=
e maintained under 145=B0 C or a permanent change in resistance will occur."

Deltec shunts are the ones commonly used with E-meters/Link-10s. Bear in m=
ind, however, that the Deltec shunts are calibrated for +/-0.25% accuracy a=
nd it is quite possible that the permanent change in resistance that may oc=
cur due to running them at higher than intended currents may be significant=
to someone requiring the +/-0.25% accuracy and completely irrelevant for E=
Vers.

Cheers,

Roger.

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