VDO Ammeter

[Raybo]

Hi,

 

I have been lurking on the forum for a while since we purchased our first boat last year. Its about time for my first proper post.

 

Amongst the equipment left by the previous owner is a "new" VDO Oceanline 80-0-80 ammeter, but no shunt. The meter seems like an expensive bit of equipment and it would be a shame not to use it. I'm no electrickery expert, but I've been reading previous threads and think I understand the principle of how a shunt works, and where it should be "plumbed" in, but am none the wiser about how to get hold of an appropriate shunt. I gather the spec of the shunt depends on the operating voltage of the ammeter (50mV / 75mV but I can't find this info anywhere on the VDO tech specs) and the amperage measured (but I'm not sure if this is to be matched to the meter - i.e. 80A or the current to be measured - probably the alternator output)

 

Original VDO items seem to be unavailable (except at ludicrous prices from the States - $90+ without P&P). Can anyone give me a steer on how to specify the shunt?

 

A related query - the back of the ammeter has 4 terminals (in addition to the backlight bulb): +, _, 1, 2. I guess I wire up + & -; does anyone know what 1 & 2 are for?

 

Cheers,

Ray.

[Nickhlx]

A related query - the back of the ammeter has 4 terminals (in addition to the backlight bulb): +, _, 1, 2. I guess I wire up + & -; does anyone know what 1 & 2 are for?<br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 252); ">

Possibly the backlight ?

Nick

[ditchcrawler]

Is this it http://www.egauges.com/pdf/vdo/0-515-012-154.pdf

[Arthur Brown]

How old is it? Several old cars with ammeters up to 60 - 0 - 60 amps were direct reading and passed the full current through the coil (probably three turns of fat wire) Can you see anything through the casing?

 

Can you pass a small current through it under control! Does the needle move or not?

[Raybo]

Is this it http://www.egauges.com/pdf/vdo/0-515-012-154.pdf

 

Thanks Ditchcrawler, but it doesn't look like it is the same as the one in that schema. It definitely works with a shunt, according to the limited specs here:

 

http://www.vdo.com/generator/www/com/en/vdo/main/hidden/_archive_old_data/ocean_line/ocean_line_engine_monitoring/ocean_line_engine_monitoring_instruments_en.html

 

and has a spin-on rear fitting rather than brackets.

 

Nickhix - those terminals 1 & 2 are additional to the ones coming out of the backlight.

 

Cheers,

Ray.

[Nickhlx]

Thanks Ditchcrawler, but it doesn't look like it is the same as the one in that schema. It definitely works with a shunt, according to the limited specs here:

 

http://www.vdo.com/g...ruments_en.html

 

and has a spin-on rear fitting rather than brackets.

 

Nickhix - those terminals 1 & 2 are additional to the ones coming out of the backlight.

 

Cheers,

Ray.

 

Sorry Ray - I missed that first time round..

 

Nick

[Raybo]

How old is it? Several old cars with ammeters up to 60 - 0 - 60 amps were direct reading and passed the full current through the coil (probably three turns of fat wire) Can you see anything through the casing?

 

Can you pass a small current through it under control! Does the needle move or not?

 

I think it was manufactured in 2003. The specs online certainly don't give any idea that it should be wired up inline. It'll be a few days before I can get back to pass any current though it, but would it break if its expecting only a few mA via a shunt?

 

Ray.

[Richard10002]

On the Chinese meters and shunts, two of the wires read the voltage across the shunt, and the other two wires provide the power to the meter.

[Nickhlx]

On the Chinese meters and shunts, two of the wires read the voltage across the shunt, and the other two wires provide the power to the meter.

 

....which is why we are all wondering why it seems to have six connections

 

Nick

[ditchcrawler]

Try this one for size http://www.vdo-instruments.com/media/instructions/0%20515%20012%20082%20--%20Shunted%20Ammeter.pdf

[nicknorman]

So 6 connections:

2 for the light

2 to power the gauge

2 for the shunt

 

Unfortunately the PDF from DC still sheds no light on the type (resistance or voltage drop) of the shunt. It might be easiest to work it out by experiment - ie work out what voltage is needed to give full scale ( probably 75mV or the like) from whichit can easily be calculated what resistance value is needed to drop this voltage at 80A.

 

One note of caution, if the shunt is installed in the +ve as shown in the PDF, both wires to the gauge should be fused near the shunt. If in the -ve perhaps not so necessary but a good idea (consider the case of a fault making the shunt open-circuit, then the 80A is trying to go through the thin wires to the meter).

[smileypete]

I think it was manufactured in 2003. The specs online certainly don't give any idea that it should be wired up inline. It'll be a few days before I can get back to pass any current though it, but would it break if its expecting only a few mA via a shunt?

Try emailing VDO technical support, if they're not forthcoming then 1 metre of wire carrying 1 amp will drop 17 millivolts, see what this reads on the meter.

 

Then get the nearest shunt that will read lower and hacksaw away (to increase the voltage drop at a given current), that's more or less how they're calibrated.

 

 

cheers, Pete.

~smpt~

Edited July 16, 2012 by smileypete

[Raybo]

Try this one for size http://www.vdo-instruments.com/media/instructions/0%20515%20012%20082%20--%20Shunted%20Ammeter.pdf

 

That's the fella! Many thanks Ditchcrawler. I've spent hours looking for that.

 

The wiring looks different to how I was expecting, so I will need to have a think.

 

Ta,

Ray.

[nicknorman]

1 metre of wire carrying 1 amp will drop 17 millivolts, see what this reads on the meter.

Is this any particular material/ x-section of wire, or just magic calibrating wire?

[smileypete]

Is this any particular material/ x-section of wire, or just magic calibrating wire?

Oops, sorry forgot to say 1mm². Just scale it inversely for other sizes, so 8.5 millivolts for 1 amp through 1 metre of 2mm²

 

Basically 1 metre of 1mm² wire has 17 milliohms resistance.

 

Still, if the OP contacts VDO, they might get lucky with finding the right shunt.

 

cheers, Pete.

~smpt~