Smiths battery gauge

[Mr Spigot]

I fitted a Smiths battery gauge a few months ago which worked fine showing the level of charge in the battery. A few weeks ago it stopped working, with the needle staying on the extreme left 'off charge' position.

Smiths battery gauge.jpg (28.4 KiB) Viewed 1871 times

I checked with a circuit tester and there is a current going through as the bulb lights up so the connections look to be good. Any ideas what has gone wrong and is it something that might be repairable or should I seek a replacement? Electrics are not my strong point!

[oliver90owner]

Have you considered that perhaps the gauge is working properly? Easy to check.

[Grumpy21]

Not familiar with the specific gauge but generally the bulb is fed from a different supply to the actual gauge. Ie there’s usually 3 connections, +ve to the bulb, +ve to the gauge and common earth (-ve on battery)

[Mr Spigot]

I would be very surprised if the gauge is working as it does not move at all, the battery is new and the car starts and runs fine and all the electrics work as they should. I could put a voltmeter across it to check I suppose?
I have not got a bulb fitted yet as the car is going to be re wired and the gauges repositioned. There is a live feed to one terminal and the other goes to earth.

[Grumpy21]

Now I’m confused. In your first post you said ‘the bulb lights up’ but in the last you say there’s no bulb fitted. ???

If it’s out of the car simply connecting the + and - to a battery should make the needle swing into the green

[Mr Spigot]

Sorry for the confusion! The bulb on the circuit tester lights up confirming a current is going through it. However there is no movement on the needle.

[geoberni]

Sorry for the confusion! The bulb on the circuit tester lights up confirming a current is going through it. However there is no movement on the needle.

That depends where you placed the Circuit tester. In fact, I can't think of a way a Circuit tester will tell you that is OK, and be lit up (if it's all connected).
The Gauge is just a Volt Meter, hence, here's the back of a Voltmeter....
So if you get one of these Test Lamp tools and connect it between Earth and Point A, it will light up irrespective of whether the gauge is working or not.
If you connect it to Point B and it lights up, then the Earth connection is open circuit because Point B should be at Earth potential.
If you connect it to Pint B and it doesn't light up, it doesn't tell you if there a supply coming through the gauge or not.
Only if you disconnect the earth cable from Point B and then try the test lamp does it tell you if the gauge has continuity through it.

Volt tester.JPG (44.92 KiB) Viewed 1741 times

[Mr Spigot]

Thanks for the helpful instructions. I dug up my Gunsons Sparktune voltmeter and when applied to the live feed 'A' with the ignition on and the engine running, it showed a healthy 14 volts. However, when I disconnected the earth lead and applied the test to 'B', there was nothing, suggesting that my first assumption was right and that the gauge has failed as no current is passing through it.
Unless there is a simple way to fix this I suppose I will need to get a new gauge.

[daveejhitchins]

Thanks for the helpful instructions. I dug up my Gunsons Sparktune voltmeter and when applied to the live feed 'A' with the ignition on and the engine running, it showed a healthy 14 volts. However, when I disconnected the earth lead and applied the test to 'B', there was nothing, suggesting that my first assumption was right and that the gauge has failed as no current is passing through it.
Unless there is a simple way to fix this I suppose I will need to get a new gauge.

Next step is to open-up the gauge and check for broken or badly soldered joints - some photos would help once opened.

Dave H.

[geoberni]

Thanks for the helpful instructions. I dug up my Gunsons Sparktune voltmeter and when applied to the live feed 'A' with the ignition on and the engine running, it showed a healthy 14 volts. However, when I disconnected the earth lead and applied the test to 'B', there was nothing, suggesting that my first assumption was right and that the gauge has failed as no current is passing through it.
Unless there is a simple way to fix this I suppose I will need to get a new gauge.

You might find this helpful...
The guy has been quite detailed.
http://www.jensenhealey.com/forums/view ... forum_id=7

[Mr Spigot]

Well I finally got round to taking this off and, sure enough, one end of the wire had become disconnected, breaking the circuit. I looked at the link http://www.jensenhealey.com/forums/view ... forum_id=7 which shows a similar problem. As he found out, the wire is very fine and while I could try soldering it, he had to use a heat shrunk sleeve to hold the wire against the post. I could try this but does anyone have any other suggestions?

[svenedin]

I’m not sure how the wire was originally secured or where it was attached. Maybe you could crimp on an uninsulated connector and solder that on to wherever it attaches?

[geoberni]

As he found out, the wire was attached using as he put it 'a green enamel' and the terminal post is a huge heatsink.

Search for 'Conductive Wire Glue'. It might cost you £5 or more but really useful stuff for such problems.

[svenedin]

Never heard of conductive wire glue. Looked it up. Clever idea! Must remember that.

[Mr Spigot]

Many thanks! I have just ordered a small pot (9ml) for £7. That will save a lot of fuss and swearing with a soldering iron!

[Mr Spigot]

Well, I finally got round to attending to this and cleaned up the end of the wire and scraped the old enamel off the post and used the wire glue to stick the wire back on the post and applied a small drop of Superglue afterwards to make sure. The trickiest part was getting it all back together in the right order, but having replaced the glass seal with a new one and replaced the bezel, I connected it up to a battery and the needle moved up to the 12v point. I shall now have to connect it up in the car and try it with the engine running but so far so good.

[oliver90owner]

Well done for both persevering, and for reporting back after making the fix. Many don’t bother and when the same symptoms arise for another owner, they have to start the process from scratch.