Voltmeter Gauge

[centro]

Im looking for a 4 Digit LED Voltmeter Gauge (52mm) so I can get an accurate reading of my Leisure batty. — Does a 4 digit version exist?

[ghost123uk]

I can tell you that I have had 3 different ones off ebay. 2 of them were miles out of calibration (>0.5V). They varied with temperature too, a common fault in poorly designed measuring circuits. So take care as a .5 volt discrepancy is quite a big deal when it comes to measuring the 11.5 to 14.5 volts that is relevant to leisure battery state. This one (despite the price) LINK is accurate (checked against my calibrated Fluke meter). Note also that they do draw a current that is not insignificant in use (cannot remember the actual figure, but over 100mA), so you really need to arrange an on / off switch for it.

[ghost123uk]

p.s. = imho you don't need a 4 digit one an accurate 3 digit one will be fine. The last digit on a 4 digit one will be flicking about all over the place under normal operating conditions anyway.

[Woodyyellow]

If I can jump into this thread;
I would like to wire in a volt meter to show readings from both the main battery and leisure battery with a switch. If the one you recommend is suitable, can you provide a simple wiring diagram please?
Thanks.

[CJH]

I did exactly that, using the gauge that Ghost linked to above.

The gauge needs a positive feed (from which it measures the voltage) and an earth. The earth is self-explanatory. I took the positive feed from the centre terminal of this switch


The good thing about this switch is it has a centre-off position, so if you're leaving the van you can turn the gauge off so it doesn't drain either of the batteries.

Then I connected a feed from the leisure battery to one of the outer terminals and a feed from the starter battery to the other outer terminal. If you're running dedicated feeds, make sure they're fused near the battery, make sure the connections are good, and make sure you use a decent gauge wire so as not to create a voltage drop.

You can actually get to the backlight wires in that gauge separately, so it's possible to feed the backlight circuit from the dashboard lighting circuit - someone on here did that I believe. Without that mod the backlight is on all the time.

[centro]

I can tell you that I have had 3 different ones off ebay. 2 of them were miles out of calibration (>0.5V). They varied with temperature too, a common fault in poorly designed measuring circuits. So take care as a .5 volt discrepancy is quite a big deal when it comes to measuring the 11.5 to 14.5 volts that is relevant to leisure battery state. This one (despite the price) LINK is accurate (checked against my calibrated Fluke meter). Note also that they do draw a current that is not insignificant in use (cannot remember the actual figure, but over 100mA), so you really need to arrange an on / off switch for it.

I currently have a Tim Voltmeter Like this: http://www.ebay.co.uk/itm/Tim-Voltmeter ... 1045136481" onclick="window.open(this.href);return false;
So Ideally want a 52mm Digital one to replace it as I find the Tim a bit vague.

[ghost123uk]

Don't think I have seen a round digital meter - stick an oil pressure gauge in that hole and use a rectangular gauge

[itchyfeet]

I can tell you that I have had 3 different ones off ebay. 2 of them were miles out of calibration (>0.5V). They varied with temperature too, a common fault in poorly designed measuring circuits. So take care as a .5 volt discrepancy is quite a big deal when it comes to measuring the 11.5 to 14.5 volts that is relevant to leisure battery state. This one (despite the price) LINK is accurate (checked against my calibrated Fluke meter). Note also that they do draw a current that is not insignificant in use (cannot remember the actual figure, but over 100mA), so you really need to arrange an on / off switch for it.

Thanks for the tip off, my 99p voltmeter turned up today with a kowloon post office stamp, even with the £2.40 postage its a bargain

Checked it against my works calibrated agligent meter and it was 0.02v out
measured current draw and it was tiny, 0.00somethingA

[ghost123uk]

Yes, I was wrong when I said that one draws ~100mA (that was another one I have). In another post (somewhere) I posted that it actually draws just 7mA, which is of no bother at all of course

[Dazco]

Got mine to fit this weekend

[CovKid]

I agree. Since I first posted this mod in WIKI and the youtube vid, mine has been connected permanetly (with LED on) for weeks on end (and it been in there 2-3 years at least) and uses nowt. The normal drop you'd get in a battery from sitting there would be faster than what the meter consumes.

Yes, I was wrong when I said that one draws ~100mA (that was another one I have). In another post (somewhere) I posted that it actually draws just 7mA, which is of no bother at all of course

[Negativegravity]

I used that one ghost posted. Seemed accurate when tested but once fitted, was out by nearly a half volt! Messaged the guy on ebay and he sent me a new one. Ill try this one this weekend. Hopefully more luck!

[CJH]

I used that one ghost posted. Seemed accurate when tested but once fitted, was out by nearly a half volt! Messaged the guy on ebay and he sent me a new one. Ill try this one this weekend. Hopefully more luck!

It's possible that the wiring to your gauge is dropping some voltage. Did you put your multimeter across the feed to the gauge at the point where that feed attaches to the meter?

[ghost123uk]

I used that one ghost posted. Seemed accurate when tested but once fitted, was out by nearly a half volt! Messaged the guy on ebay and he sent me a new one. Ill try this one this weekend. Hopefully more luck!

It's possible that the wiring to your gauge is dropping some voltage. Did you put your multimeter across the feed to the gauge at the point where that feed attaches to the meter?

Not wishing to disagree with you Chris, but I disagree Normally voltage drop down wiring is entirely dependant on the current flowing in the wire (Ohms law) and as these meters use so little current any voltage drop down even the very thinnest wire would be unmeasurable with ordinary test meters.

I think it likely that, as so often with cheap mass produced goods, poor quality control is the likely cause of Negativegravity's one being out of calibration.

[itchyfeet]

^^^^^^ I nearly wrote that then i realised that if you measure in two different places and something else is drawing current down tge wire you will see a voltdrop, i think thats what cjh meant