Voltmeter Not Moving And Stuck On 11Volts

[Guest Martin.stgeorge]

I have just made a new dash which ment I had to move the dials but when putting all the wires back in, the voltmeter has stopped at 11volts and will not move.

 

Have I fried it? Or is there something I can do to revive it?

[IanS]

Need a bit more info.

Do you mean that on switch on the needle moved to 11V and stayed there when switched off? If so the meter has been damaged.

If on switch on it moves to 11V and drops back to 0 when switched off then you have a bad connection or a slightly flat battery.

To check that you realy have switched off disconnect the battery and if the reading is still 11V then the meter is probably damaged.

[Guest Martin.stgeorge]

Many thanks for the reply. Even with no power it is stuck at 11v. On-off, disconnected. So have killed it?

 

:-(

 

 

[sj-bradley]

Yes, it looks that way I'm afraid.

 

Simon.

[Guest Martin.stgeorge]

Oh no. I think there is a lesson learnt. Thanks for your replays.

 

Now just have to find a replacement.

 

I will post a picture of the dash is anyone is interested tomorrow.

[IanS]

I am always interested in what people modify thier cars too

[Guest Martin.stgeorge]

Here is a picture of the voltmeter and the bash.

 

 

[Grim]

Did it sit at 11 when the ignition was off before? if so it might just need reconnecting? have you changed the wiring?

could you have connected it to a permanant live via a voltage regulator (common to have a regulator with smiths type gauges, just not for the voltmeter). Disconnect the positive feed to it and put a wire directly from the battery to the gauge, and see what it reads.

 

On the up side, 2nd hand smiths gauges of this type are cheap!

Edited June 10, 2014 by Grim

[PaulF2B]

If you disconnect all the wiring from the meter, then connect a 12V battery charger across the 2 terminals (+ and -), see if it reads above the 11V it was fixed at.

 

If it does, your meter is still alive and you can start troubleshooting the dash wiring.

 

If it never reads anything other than 11V in all situations, then you could try to dismantle / repair it, otherwise afraid it's time to get the wallet out!

[sj-bradley]

Be careful about doing that as some battery chargers need the battery load to bring their output voltage down to charging levels.

 

If you have a multimeter, check the charger voltage before connecting to the meter.

 

You can also use a 9 volt battery and some 2 or 3 1.5 AA type to give you between 12 and 13.5 (ish) volts depending on the charge in the little batteries. They are safer as they cannot supply a high current and so will protect the meter. A charger can supply several amps and could be a problem.

 

Simon.

[fry61]

 

 

 

 

. They are safer as they cannot supply a high current and so will protect the meter. A charger can supply several amps and could be a problem.

 

Simon.

 

The internal resistance of the meter is so high it will not allow a high current flow unless the meter windings are faulty, but your other point on the charger is correct , Simon -- IMO

[sj-bradley]

I was assuming the meter might be faulty so I wanted some way to limit the current through the meter.

 

You are correct, the resistance of the meter SHOULD be high and that could be tested to find the resistance before attaching any volts to it.

 

Just putting a charger across the meter with an unknown output voltage and current COULD be dangerous. Although a decent charger should be short circuit protected.

 

But which is best to use, an expensive charger, or some disposable batteries ?

 

Simon.

[PaulF2B]

Simon's suggestion of using dry cells is a good idea.

 

Also it is always best to test your instruments with a with a multimeter measuring impedance (Ohms) before doing any other tests or even before installing them.

 

Volt meters should be very high impedance "many K Ohms" as they are connected across the supply (in parallel) and you don't want them to drain a battery / waste energy. If one were to fail and go low impedance it would likely blow the fuse.

 

Ammeters however are wired in series and will be very low impedance typically under 1 ohm so they do not limit the current in the circuit it is feeding.

 

HTH

[Longboarder]

Am I missing something or would it not be simplest to just connect it across a car battery. We all have one of those, if not in the kit then in the nearest tin top and giving 12.5+.

 

Nigel

[sj-bradley]

You could do that, but if the voltmeter has failed short circuit, then it would be like dropping a spanner across a battery.

 

Check resistance of meter BEFORE doing that.

 

Simon.