[EVDL List]

Hello

I have on of those emeter "voltage prescaler 0-500 vdc"

Is there a way to test to make sure it works ok?

I seems only knock off about 10% of the voltage ...


thanks
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[EVDL List]

What emeter is it designed for?

A prescaler is a resistor that is exactly 9x the resistance of the meter its
intended to be used with.

The volt meter you used to test it with is perhaps 1/9th the resistance of
the prescaler?

Matt

-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On Behalf
Of m gol
Sent: Sunday, 15 February 2009 2:56 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] emeter voltage prescaler 0-500 vdc

Hello

I have on of those emeter "voltage prescaler 0-500 vdc"

Is there a way to test to make sure it works ok?

I seems only knock off about 10% of the voltage ...


thanks
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http://evdl.org/help/index.html#conv
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6:29 PM


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[EVDL List]

link 10 emeter...

I would think it would take the voltage down more than 10%?

[quote] matt <mc.xxx@xxx.xxx.au> wrote:

> What emeter is it designed for?
>
> A prescaler is a resistor that is exactly 9x the resistance of the meter
> its
> intended to be used with.
>
> The volt meter you used to test it with is perhaps 1/9th the resistance of
> the prescaler?
>
> Matt
>
> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
> Behalf
> Of m gol
> Sent: Sunday, 15 February 2009 2:56 PM
> To: Electric Vehicle Discussion List
> Subject: [EVDL] emeter voltage prescaler 0-500 vdc
>
> Hello
>
> I have on of those emeter "voltage prescaler 0-500 vdc"
>
> Is there a way to test to make sure it works ok?
>
> I seems only knock off about 10% of the voltage ...
>
>
> thanks
> _______________________________________________
> General EVDL support: http://evdl.org/help/ Usage guidelines:
> http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>
> --
> No virus found in this incoming message.
> Checked by AVG.
> Version: 7.5.552 / Virus Database: 270.10.23/1952 - Release Date:
> 13/02/2009
> 6:29 PM
>
>
> _______________________________________________
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> Usage guidelines: http://evdl.org/help/index.html#conv
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[EVDL List]

How did you connect it and if you can,
please measure the resistance of the
pre-scaler (it is really only 1 resistor)

Regards,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: xxx@xxx.xxx
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of m gol
Sent: Sunday, February 15, 2009 2:50 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] emeter voltage prescaler 0-500 vdc

link 10 emeter...

I would think it would take the voltage down more than 10%?

[quote] matt <mc.xxx@xxx.xxx.au> wrote:

> What emeter is it designed for?
>
> A prescaler is a resistor that is exactly 9x the resistance of the
meter
> its
> intended to be used with.
>
> The volt meter you used to test it with is perhaps 1/9th the
resistance of
> the prescaler?
>
> Matt
>
> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
> Behalf
> Of m gol
> Sent: Sunday, 15 February 2009 2:56 PM
> To: Electric Vehicle Discussion List
> Subject: [EVDL] emeter voltage prescaler 0-500 vdc
>
> Hello
>
> I have on of those emeter "voltage prescaler 0-500 vdc"
>
> Is there a way to test to make sure it works ok?
>
> I seems only knock off about 10% of the voltage ...
>
>
> thanks
> _______________________________________________
> General EVDL support: http://evdl.org/help/ Usage guidelines:
> http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>
> --
> No virus found in this incoming message.
> Checked by AVG.
> Version: 7.5.552 / Virus Database: 270.10.23/1952 - Release Date:
> 13/02/2009
> 6:29 PM
>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
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[EVDL List]

Do you mean by this that it reads only 10% of the pack voltage? You will
need to ignore the decimal point, if it is a Link-10 (used to be E-meter);
that is, as I recall, the only downside to using it.

Joseph H. Strubhar

Web: www.gremcoinc.com

E-mail: xxx@xxx.xxx


----- Original Message -----
From: "m gol" <gol.xxx@xxx.xxx>
To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
Sent: Saturday, February 14, 2009 9:56 PM
Subject: [EVDL] emeter voltage prescaler 0-500 vdc


> Hello
>
> I have on of those emeter "voltage prescaler 0-500 vdc"
>
> Is there a way to test to make sure it works ok?
>
> I seems only knock off about 10% of the voltage ...
>
>
> thanks
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>


--------------------------------------------------------------------------------



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18:01:00

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[EVDL List]

[quote]m gol wrote:

> I would think it would take the voltage down more than 10%?

Nope, not necessarily. The prescaler is just a suitably-sized resistor that goes in series with the pack positive connection. Measure the resistance of between the positive input and positive output leads, and tell us what you see.

The prescaler also includes a zener diode between the positive and negative output leads that is supposed to limit the peak voltage at the meter to <50V in the event that you happen to apply more than 500V to the input of the prescaler.

If, for instance, someone happened to connect the prescaler backwards, and apply >50V across its output leads, then the protection zener would get fried. The prescaler would likely still work, but you would not have any protection for your meter in the event of an over-voltage event.

The surest way to test the prescaler is to connect it to the meter and power the meter from a single 12V battery. Leave the positive input lead disconnected initially and verify that the meter shows 0V. Then connect the positive input of the prescaler to the same 12V battery and verify that the meter reads 1.2V (it will not read 12V until you program the meter so it knows you are using a 500V prescaler).

Cheers,

Roger.

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[EVDL List]

[quote]Joe wrote:

> Do you mean by this that it reads only 10% of the pack
> voltage? You will need to ignore the decimal point, if it is
> a Link-10 (used to be E-meter); that is, as I recall, the
> only downside to using it.

If you use either a 100V or 500V prescaler with your E-meter, you need to program the meter to know that the prescaler is present (and which one it is). After this, the display will read with the voltage properly scaled. I'd tell you how to do it if I could recall, but it's there in the manual if you have a look for it.

Cheers,

Roger.

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[EVDL List]

I meant DMM.

Is there a way to test the voltage drop on the prescaler before hooking it
up with the emeter.

[quote] Jeff Shanab <xxx@xxx.xxx> wrote:

> > Hello
> >
> > I have on of those emeter "voltage prescaler 0-500 vdc"
> >
> > Is there a way to test to make sure it works ok?
> >
> > I seems only knock off about 10% of the voltage ...
> >
> >
> > thanks
>
> How are you measuring this voltage drop? If it is open circuit without the
> meter connected, the meter itself is the rest of the circuit and it is very
> high impedeance. This is one reason why they have a specific order
> connecting things to the emeter.
>
>
> _______________________________________________
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> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
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[EVDL List]

With a multimeter you can measure the resistance
of the Emeter's voltage sense input (pack voltage)
and the resistance of the prescaler resistor.

For example, if the Emeter has 100 kOhm resistance
then the prescaler must be exactly 9 times higher or
900 kOhm so that the total resistance of Emeter +
prescaler equals 1 MOhm (1 million Ohms) and the
current through the Emeter at 10x the input voltage
is equal to the current without prescaler at 1/10
of the voltage now.
In other words: the decimal point has shifted a position.
For example with a 288V pack, the Emeter sees 28.8 Volts.
The software has been adapted to multiply the input by 10.

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: xxx@xxx.xxx
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of m gol
Sent: Monday, February 16, 2009 10:36 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] emeter voltage prescaler 0-500 vdc

I meant DMM.

Is there a way to test the voltage drop on the prescaler before hooking
it
up with the emeter.

On Mon, Feb 16, 2009 at 7:16 AM, Jeff Shanab <xxx@xxx.xxx>
[quote]wrote:

> > Hello
> >
> > I have on of those emeter "voltage prescaler 0-500 vdc"
> >
> > Is there a way to test to make sure it works ok?
> >
> > I seems only knock off about 10% of the voltage ...
> >
> >
> > thanks
>
> How are you measuring this voltage drop? If it is open circuit without
the
> meter connected, the meter itself is the rest of the circuit and it is
very
> high impedeance. This is one reason why they have a specific order
> connecting things to the emeter.
>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
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