Where is the ammeter shunt located?

J

Jostein Soppeland

New Member
Having taken over a P6 3500 LHD from 1970, I find that the loom is badly altered. Among other things the ammeter shunt is just removed and the cables supposed to connect to it are connected elsewhere. The ammeter is not connected.
Now, I am unable to find precisely where shunt should be located.
Are ammeter shunts available?
Information is greatly appreciated.
 
Hi.
Here's a picture of the shunt , the 2 wires shown connect to the amp meter.
Here's the one fitted to my LHD NADA with round dial dash.
Clive.20171008_124729.jpg 20171008_124300.jpg 20171008_124351.jpg
 
must be less than that, check the scale. If a modest 10 amps were going through it, you'd have 5 volts across the shunt and it would be dissipating 50watts!
 
I agree with Peter, the shunt resistance should be much ess than that. On the order of .001 ohms. You'd need a four wire setup to measure it (test method that eliminates the resistance of the test leads & probes).

If you could determine the mA needed to drive the ammeter full scale, I think you could work backwards and calculate the shunt resistance.

Yours
Vern
 
Just refreshed my memory, I'm wrong. It's the voltage to drive the ammeter full scale you need to know, and then you can calculate the resistance needed for that voltage drop at the full scale amps from Ohms law.

Yours
Vern
 
Vern Klukas said:
I agree with Peter, the shunt resistance should be much ess than that. On the order of .001 ohms. You'd need a four wire setup to measure it (test method that eliminates the resistance of the test leads & probes).

If you could determine the mA needed to drive the ammeter full scale, I think you could work backwards and calculate the shunt resistance.

Yours
Vern
Click to expand...
I think 0.001 ohms sounds about right. If you search for ammeter shunt on ebay, you find them with resistances in that region.

ammeter shunt in eBay Motors | eBay
 
Good evening all.
Is it possible to bypass the Ammeter Shunt on a 1972 2000TC? I have a major problem with mine. All the wires from it are totally burnt out. I don't know if the Shunt itself has been damaged by the burn out. Although I am pretty certain I burnt out the wiring last year by accidentally connecting the battery the wrong way round. I also believe the shunt was partially burnt out prior to my mishap as there were burnt out wires in various areas of the car. I am wondering if this can be bypassed or even tested. Can someone shed some light for me please? Many thanks in advance.
 
Yes, you can connect all the wires either side of the shunt together. It's basically a point at which the battery and alternator connect and the power distributed. The shunt places the alternator one side and the battery the other hence it can see whether charge is flowing one way or the other. For all intents and purposes the drop across the shunt is next to nothing.
 
PeterZRH said:
Yes, you can connect all the wires either side of the shunt together. It's basically a point at which the battery and alternator connect and the power distributed. The shunt places the alternator one side and the battery the other hence it can see whether charge is flowing one way or the other. For all intents and purposes the drop across the shunt is next to nothing.
Click to expand...

Good evening, Peter.

Many thanks for that. Hopefully after a rewire I should still be able to use the shunt I have removed? I will clean the shunt up before I refit it. I really hope this works. If it doesn't then could I use a bus bar or high amp distribution block?

Thanks again, Peter. I shall update you after I have done the work.

Best regards
Steve
 
If it works it works if it's burned you'll likely get no charge to the battery. The car will start as the motor is routed via a separate relay.
 
PeterZRH said:
If it works it works if it's burned you'll likely get no charge to the battery. The car will start as the motor is routed via a separate relay.
Click to expand...
Morning, Peter
I have cleaned up and rewired the Ammeter Shunt. However, the car still tries to start with no as soon as the battery is connected. I have checked all the wiring for any burnt out or shorting wiring but have found none. I replaced all the burnt wiring before repairing the Ammeter Shunt. I am now at a loss as to where I go from here. I am hoping I do not have to buy a new Shunt as they are £145.00. The only other thing I can think of doing is directly connecting the wires without using the shunt. Would that idea work? Have you or anyone else on this Forum have any ideas, please?
 
Yes! Connect everything together at that was connected to either side of the shunt. All that will happen is the ammeter won't read (in fact also remove the two wires with the braided covering which connect the meter). The shunt serves no purpose whatsoever except to provide a small voltage to drive the meter.

That way you'll know whether that was the problem or you have issues elsewhere.
 
PeterZRH said:
Yes! Connect everything together at that was connected to either side of the shunt. All that will happen is the ammeter won't read (in fact also remove the two wires with the braided covering which connect the meter). The shunt serves no purpose whatsoever except to provide a small voltage to drive the meter.

That way you'll know whether that was the problem or you have issues elsewhere.
Click to expand...
Thanks, Peter. I'll do that. I will let you know the results later. Thanks again. :) :)
 
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