Strange E-meter Issue

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Strange E-meter Issue

Mark Dutko
I was doing some work on my car and I am now having problems with my e-
meter.    The meter reads full pack voltage but no amps, well it  
reads .6 Amps with no load and when it's charging as well, it is sort  
of stuck on .6 amps. If the shunt is measuring the correct voltage  
then what would cause the amps to not read. Prescaler? e-meter?


Thanks,

mark


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Re: Strange E-meter Issue

Jon Glauser
Some questions:

Does your emeter have an isolated DC-DC power supply?

Are you sure the current sense wires are still attached to the shunt and
the emeter?

While working on your car could you have accidentally touched any
voltage (referenced from battery pack negative) to the current sense wires?


Mine stopped working in a similar way when I messed up the grounds. I
put the meter ground to 12V ground, and it basically connected the
chassis ground to the pack ground through the emeter circuitry. Whoops..
ended up cooking several parts in my emeter. Its is repairable however,
and a few dollars worth of parts later I'm good again! This time I have
an isolated DC-DC supply too!

-Jon



Mark Dutko wrote:

> I was doing some work on my car and I am now having problems with my e-
> meter.    The meter reads full pack voltage but no amps, well it  
> reads .6 Amps with no load and when it's charging as well, it is sort  
> of stuck on .6 amps. If the shunt is measuring the correct voltage  
> then what would cause the amps to not read. Prescaler? e-meter?
>
>
> Thanks,
>
> mark
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>  

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Re: Strange E-meter Issue

Bob Bath
My guess is a fried prescaler.
  I had a similar issue.  You should have like, 6 megs across the resistor, hot-to-hot on the prescaler.  Don't take my word for it though; call up Xantrex, or go to their website, and they have a specific diagnosing process to see if it is in fact the prescaler.
  I should've gone there first, and would've saved the $100 in shipping and diagnosing a "perfectly fine" E-meter, and gone straight to source of the problem!
  Good luck,  

Jon Glauser <[hidden email]> wrote:
  Some questions:

Does your emeter have an isolated DC-DC power supply?

Are you sure the current sense wires are still attached to the shunt and
the emeter?

While working on your car could you have accidentally touched any
voltage (referenced from battery pack negative) to the current sense wires?


Mine stopped working in a similar way when I messed up the grounds. I
put the meter ground to 12V ground, and it basically connected the
chassis ground to the pack ground through the emeter circuitry. Whoops..
ended up cooking several parts in my emeter. Its is repairable however,
and a few dollars worth of parts later I'm good again! This time I have
an isolated DC-DC supply too!

-Jon



Mark Dutko wrote:

> I was doing some work on my car and I am now having problems with my e-
> meter. The meter reads full pack voltage but no amps, well it
> reads .6 Amps with no load and when it's charging as well, it is sort
> of stuck on .6 amps. If the shunt is measuring the correct voltage
> then what would cause the amps to not read. Prescaler? e-meter?
>
>
> Thanks,
>
> mark
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>

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Re: Strange E-meter Issue

Mark Dutko
In reply to this post by Mark Dutko
I have an isolated dc/dc and the wires are still connected to the  
shunt and the e-meter. I reset the meter but it still just reads .5A

M

On Dec 31, 2007, at 7:09 PM, Jon Glauser wrote:

> Some questions:
>
> Does your emeter have an isolated DC-DC power supply?
>
> Are you sure the current sense wires are still attached to the shunt  
> and
> the emeter?
>
> While working on your car could you have accidentally touched any
> voltage (referenced from battery pack negative) to the current sense  
> wires?
>
>
> Mine stopped working in a similar way when I messed up the grounds. I
> put the meter ground to 12V ground, and it basically connected the
> chassis ground to the pack ground through the emeter circuitry.  
> Whoops..
> ended up cooking several parts in my emeter. Its is repairable  
> however,
> and a few dollars worth of parts later I'm good again! This time I  
> have
> an isolated DC-DC supply too!
>
> -Jon
>
>
>
> Mark Dutko wrote:
>> I was doing some work on my car and I am now having problems with  
>> my e-
>> meter.    The meter reads full pack voltage but no amps, well it
>> reads .6 Amps with no load and when it's charging as well, it is sort
>> of stuck on .6 amps. If the shunt is measuring the correct voltage
>> then what would cause the amps to not read. Prescaler? e-meter?
>>
>>
>> Thanks,
>>
>> mark
>>
>>
>> _______________________________________________
>> 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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Re: Strange E-meter Issue

Lee Hart
In reply to this post by Bob Bath
Bob Bath wrote:
> My guess is a fried prescaler. I had a similar issue.  You should
> have like, 6 megs across the resistor, hot-to-hot on the prescaler.

Hot-to-hot should measure 1057K (1.057 megohms) +/-1% on the 500v
prescaler, or 118K +/-1% on the 100v prescaler.

--
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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Re: Strange E-meter Issue

Jon Glauser
In reply to this post by Mark Dutko
Somewhat related to your problem, I had blown up the current sensor
amplifier on my e-meter. I've got it figured out and fixed now (and
added the serial port option). I put some of the information I dug out here:
http://www.flickr.com/photos/imbob_yournot

If you're comfortable with electronics you could use some of this to try
to diagnose your problem.

-Jon

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Re: Strange E-meter Issue

Jon Glauser
In reply to this post by Mark Dutko
Well, easy is a relative word. It was easy for me. But I'm an electrical
engineering student, have been trained in soldering, and have a
microscope and equipment available to me. All the parts can be had
through Digikey for a few bucks. If you've never soldered before, I dont
recommend this be your learning project unless you're ambitious.
Although, what could it hurt? An emeter that doesnt read current is
pretty much useless!

-Jon

Mark Dutko wrote:
> I think this is my problem, is there an easy fix. I pulled the meter
> and it still has the problem when hooked to a 12v battery on the counter.
>

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Re: Strange E-meter Issue

Mark Dutko
In reply to this post by Mark Dutko
The soldering and repair is not an issue if there is a part that  
usually fails and it you can identify it I can fix it.


On Jan 3, 2008, at 3:39 PM, Jon Glauser wrote:

> Well, easy is a relative word. It was easy for me. But I'm an  
> electrical
> engineering student, have been trained in soldering, and have a
> microscope and equipment available to me. All the parts can be had
> through Digikey for a few bucks. If you've never soldered before, I  
> dont
> recommend this be your learning project unless you're ambitious.
> Although, what could it hurt? An emeter that doesnt read current is
> pretty much useless!
>
> -Jon
>
> Mark Dutko wrote:
>> I think this is my problem, is there an easy fix. I pulled the meter
>> and it still has the problem when hooked to a 12v battery on the  
>> counter.
>>
>
> _______________________________________________
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Re: Strange E-meter Issue

Jon Glauser
Its not so much that one part fails. It really takes some
troubleshooting to get it fixed. I have the schematic for the current
amplifier here: http://www.flickr.com/photos/imbob_yournot/2159371023/

most all of the parts involved with the current amplifier are located
here: http://www.flickr.com/photos/imbob_yournot/2104583014/
If you look closely at the photo, there are 2 resistors that are burnt
(they were green).


I say I got mine working again, but it is only partially working at this
point. It reads a value, but it is not correct (ie. pushing 8 amps
through the shunt, the emeter shows 1.7). I think I replaced a resistor
with the wrong value (hard to tell the correct value if it has been
burned off!). I need to find someone with a working emeter to help me
find component values, or even just working voltages.

-Jon



Mark Dutko wrote:
> The soldering and repair is not an issue if there is a part that  
> usually fails and it you can identify it I can fix it.
>
>  
>
>  

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