Dashboard voltmeter

[jazzdude]

My car was fitted with a dashboard voltmeter which is a good thing and also a bad thing in my opinion.

Good, in that it is another bit of useful information to have so you know what is happening with the car, and bad as in it is another thing to keep your eye on and worry about as you scan the other dials.

Recently the voltmeter has started to act irrationally giving me that feeling that my car is about to break down and leave me by the roadside. I usually drive around with it showing just under 14v, with it dropping a couple of volts if the fans come on, lights are on or you put the heater fan on. With all on it can move down to as low as 9v.

But lately, sometimes it shows me driving around with 12v with no other items on, even though yesterday I measured 13.8v at the battery and at the back of the alternator.

At the back of the voltmeter it also shows 13.8v even when the dial itself was showing 12.5v. Out on the road a few minutes later, it had crept back up to just under 14v.

Obviously there is a problem with the voltmeter so I am wondering if it can be repaired or is it a case of changing where the voltage is being read from. Looking at the mess of wires behind the dash it looks like he dial has been piggy backed off one of the the other dials somewhere.

If I need to replace it, who supplies these white faced, aluminum ringed tvr dials?

[ChimpOnGas]

Its clearly been badly installed, and a guage that gives inacurate readings is worse than no gauge at all, for a voltage gauge to give an accurate readings it needs to be connected directly to the car's battery.

I use a bluetooth device, that in the same way you should wire a voltage gauge, is connected directly to my battery.

Using an app I can get a 100% accurate live digital battery voltage readings whenever I need them.



The system is no bigger than a small box of matches and installs in under a minute, download the app to your Android phone or Iphone and your mobile device connects in seconds, I chose it because there's no wiring needed and no need to cut a hole in my dash to fit a gauge that likely wouldn't match my other TVR gauges, cheap too at just £18.00.

Here are some screen grabs from my phone after I fitted it.....



The system provides a convenient way to accurately monitor battery voltage with the engine off as above, and with the engine running as shown below.



Better still there are a couple of nice test modes too, firstly a charging test.



And secondly a cranking test.



The device has a very respectable range, I can now check my TVR battery voltage from my the kitchen so without even leaving the house or obviously as I drive. Best of all it only cost £18.00 so it's cheaper than many traditional voltage gauges and offers way more too, I've checked it's readings with a meter and its spot on so the accuracy is also excellent.

If your looking for a way to remotely monitor your battery/alternator output and run a few simple tests, I'd definitely recommended it

[Penelope Stopit]

This circuit may be of interest once the voltmeter has been repaired

[v12.24v]

Hello, do you have any starting issues or other issues which are showing low battery voltage during driving? If not, check the big main connector under the dash which connect your dials. In my Griffith (which has more or less the same wiring) I had the issue with bad connection from the power supply, the contacts in the connector getting hot and the voltage only from the dials drops down.

[Englishman]

jazzdude said:

At the back of the voltmeter it also shows 13.8v even when the dial itself was showing 12.5v. Out on the road a few minutes later, it had crept back up to just under 14v.

Obviously there is a problem with the voltmeter so I am wondering if it can be repaired or is it a case of changing where the voltage is being read from. Looking at the mess of wires behind the dash it looks like he dial has been piggy backed off one of the the other dials somewhere.

If I need to replace it, who supplies these white faced, aluminum ringed tvr dials?

Sounds like the meter mechanism itself is 'sticky'. Have you tried tapping it when under reading?

Most people use Speedy Cables, https://speedycables.com/, for repairs, but you will be without your voltmeter for a couple of months despite their name I'd suggest giving them a ring first as they are very helpful.

[ric355]

ChimpOnGas said:

I use a bluetooth device, that in the same way you should wire a voltage gauge, is connected directly to my battery.

I have one of these too. Only problem with it is that it really hammers your mobile phone battery. There are two versions of the phone app for android. Both use a lot of power but the newer version is worst, and as a result I'm on the older one (as pictured above).

It has temporarily died on me once; I had to disconnect and reconnect it to reboot it.

[ric355]

jazzdude said:

If I need to replace it, who supplies these white faced, aluminum ringed tvr dials?

Probably came from caerbont/smiths;

https://www.smiths-instruments.co.uk/tvr

They do custom stuff too, so they can probably build it if it doesn't already exist. There are some dual gauges too which can be good if you want to add a gauge and not cut another hole.

[jazzdude]

I am tempted to try and have the feed rewired to see how it works first, as I feel that the however it has been connected to the dashboard wiring, there is potentially something affecting the gauge and a clean reading there.

Which option would be more useful, wiring it to the battery or the alternator in terms of getting some notice that the 100 amp fuse is on its way out?

Or doesn't it matter?

[Englishman]

jazzdude said:

Which option would be more useful, wiring it to the battery or the alternator in terms of getting some notice that the 100 amp fuse is on its way out?

Or doesn't it matter?

The fuse is connected to the alternator and then on to the car circuitry, so connecting to the battery is the best option.

[pb450]

ChimpOnGas said:

Best of all it only cost £18.00....

Where did you find it for that price Dave? lookss like £28 on Amazon.

[ChimpOnGas]

pb450 said:

Where did you find it for that price Dave? lookss like £28 on Amazon.

EBay, I think it was a special one off deal, I've been using it for almost a year and its worked flawlessly in that time.

Its much more accurate than a traditional anologue guage, its easy to fit, requires no hole cutting in the dash and even at £28 its way cheaper than sourcing a matching guage fro Caerbont.

When I want to check my battery voltage it can be done from outside the car without even unlocking and from upto 20 ft away, or leave the app open to keep an eye on charging voltage as I drive, I can also run charging and a cranking voltage tests.

Cheaper, easier to fit, and more accurate... clearly this little Bluetooth device offers lots of benefits over an analogue guage which for me makes it a no brainer.



Here's my reading this morning, the car was driven yesterday but has been sat out on the drive all night and not on charge.... not bad for a 7.5 year old battery

Edited by ChimpOnGas on Tuesday 26th November 07:01

[ric355]

pb450 said:

Where did you find it for that price Dave? lookss like £28 on Amazon.

When I bought mine I bought through eBay but prices had already risen a bit then (in the summer of this year). I think I paid about £23. Prices on Amazon were more expensive than eBay at that time too.

[pb450]

Thanks guys. Appreciated.
I wonder if multiple units (in two cars garaged close to each other) will work independently.

[BIG DUNC]

You can have up to five paired to one phone according to the sales blurb.

[BIG DUNC]

You can have up to five paired to one phone according to the sales blurb.

[pb450]

Excellent news. I feel a couple of purchases coming on!

[ric355]

pb450 said:

Excellent news. I feel a couple of purchases coming on!

On Android, the version of software that works better with multiple devices is the newer one that I was referring to earlier when I said the battery usage is really really awful. I have not tried it recently, but last time I tried it I had to go back to the older release (there are two separate apps in the Android app store). I've no idea what it is like on iOS.