12 Volt guages

Submitted: Monday, Feb 07, 2005 at 19:17
ThreadID: 20221 Views:2217 Replies:3 FollowUps:9
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Looking in the auto shop today for a volt meter and asked if they could get a digital one to keep an eye on the second battery, seemed a bit of a problem, has anyone any idea where to pick them up. Thanks in advance
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Reply By: Member - Jeff M (WA) - Monday, Feb 07, 2005 at 20:12

Monday, Feb 07, 2005 at 20:12
I had the same thing, some D.H. at an auto sparkie place tried to tell me it would cost $1000. I loved out loud and walked out.

I bought mine from autospeed.com.au but Jaycar also do them. They have a clock, inside and outside tempas well as a volt metre with an 11.5v low voltage alarm. All for about $39inc GST.

Part Number: XC0116
AnswerID: 97142

Follow Up By: Member - Roachie (SA) - Monday, Feb 07, 2005 at 21:38

Monday, Feb 07, 2005 at 21:38
Jeff's quite right.
I've got one of the Jaycar units and it's not too bad.....

I got sick of it beeping at me for no apparent reason, so pulled it apart and cut the wires to the speaker. I also found the clock was a bit like Janette Howard in bed at night (ie: next to useless...). It runs off a couple of button batteries, so I pulled them out and don't worry about that feature. I cut the 12v cigi plug off and hard wired it to my 2nd battery. It is supposed to have a blue back light on, whenever power is present, but mine has a mind of it's own and isn't usually on even though it has full time power.
Sometimes the screen goes berserk for a while (could be seconds, minutes, hours or days) whereby the it will show all 8888888's etc.
I may have just got a dud, but I leave it there cos it does work okay MOST of the time and the voltmeter seems to be okay too.....measures to 1 tenth of a volt.
FollowupID: 355773

Follow Up By: Member - Sand Man (SA) - Tuesday, Feb 08, 2005 at 09:02

Tuesday, Feb 08, 2005 at 09:02
Geez Bill,

I'd take it back for a replacement, (even though you have modified it:-)

Mine is stock standard and works well.

I left the plug on so that I can swap between Primary and Secondary batteries, mearly by plugging it in to the appropriate socket.

The outside temperature sensor is also handy to shove in the fridge to monitor its temperature.

I'm diagonally parked in a parallel Universe!

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FollowupID: 355802

Follow Up By: Member - Crazie (VIC) - Tuesday, Feb 08, 2005 at 10:25

Tuesday, Feb 08, 2005 at 10:25
Hi Jeff

they look like a good unit, best i get myself one.


FollowupID: 355814

Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 08, 2005 at 12:12

Tuesday, Feb 08, 2005 at 12:12
Yeah Rochaie, yours sounds munted! :-) Get another, they are really good.

The clock works fine on mine, never changed the batteries on it and it keep in sycn with the GPS.

I cut the end off mine and wired it through a switch to the batteries. I can flick the switch and it switches between bat A. and bat B. Normally I leaveit on Bat B. though as the volt meter on the dash of the surf shows a rough idea of bat A.

Mine only beeps when under 11.5V but if you don't have it connected directly to the battery, ie you have other things running of the same cable you'll find that voltage drop will trigger the alarm prematually. ie if you transmit on your HF it may drop the voltage and trigger the alarm, or if you fridge cuts in etc etc etc.

The 8888888 on the display happens on mine also, but only when it's a 35c plus day and the cars been sitting in the sun, seems to be when the ambiant temp get's over 60c or so. Once the air con's been running for 10 minutes or so it comes back good. I have the outside temp sensor siliconed to the underneath of the air ram on the snorkel. Nice and shaded from the sun, plenty of fresh air and away from the engine heat for an accurate temp. I find the inside temp is pretty inaccurate though because its mounted just above my stereo and the stereo get's hot while playing MP3s and seems to through it out a bit.

My backlight is always on when the unit is on.ie If I'm monitoring aux bat it's on, if I'm monitoring Bat A it's on when the keys are in.
FollowupID: 355831

Reply By: Andrew from TrekTable - Monday, Feb 07, 2005 at 22:30

Monday, Feb 07, 2005 at 22:30

I had a similar project recently which I will share with you. I wanted to know Volts plus Amps in or out. Problem was, most ammeters are symmetrical (ie -20 to +20) which was no good because I wanted to know how much current was going in (approx 30 - 100 Amps) and then also be able to tell accurately how much was coming out (-0.5 to -12 Amps) when camping etc. So if I used a symmetrical ammeter with high enough scale to read max current in, I wouldn't get a very accurate current out figure because the scale would be too large.

So I built a digital meter that allows me to measure volts and Amps via a 2 way switch. Because it is digital, I get accurate high and low current Amp readings and with the flick of the switch, I can see battery volts.

Very simple design using:
3.5 digit LCD meter from DickSmith ($10 I think)
Double Pole, Dual Throw switch $5
3 resistors (one pot) $2 (simple voltage divider for Voltmeter)
100A Shunt $30
Case & wires, etc $10

The standard 3.5 digit LCD meter will read Amps direct from the Shunt & a simple voltage divider will give you the scale you need for the voltmeter. Only limitation is that you are restricted to one decimal place (eg 11.5V) because I wanted 100A max scale but it works fine for me.

I find this works very well for me & I can provide the design if required.

AnswerID: 97174

Follow Up By: anoldbuddy - Monday, Feb 07, 2005 at 23:20

Monday, Feb 07, 2005 at 23:20

I had a very similar project in mind. LCD 200mV meter from Oatley for $9 reading directly from a shunt from one of the solar shops. I would like to see how you put it together - any chance of passing on your design?

FollowupID: 355785

Follow Up By: Shaker - Tuesday, Feb 08, 2005 at 09:28

Tuesday, Feb 08, 2005 at 09:28
Wish I was that clever with electronics!
I would also be very keen to see your design.
FollowupID: 355804

Follow Up By: Andrew from TrekTable - Tuesday, Feb 08, 2005 at 10:12

Tuesday, Feb 08, 2005 at 10:12
Hi Guys,

I've had a few enquiries about my cheap and cheerful volt & ammeter design so I'll draw it out tonite & post a link for it. Standby.

FollowupID: 355811

Follow Up By: Savvas - Tuesday, Feb 08, 2005 at 11:49

Tuesday, Feb 08, 2005 at 11:49
Hi Andrew,

Sounds good ... standing by
FollowupID: 355829

Follow Up By: Andrew from TrekTable - Tuesday, Feb 08, 2005 at 23:03

Tuesday, Feb 08, 2005 at 23:03
Ok everyone,

I've drawn up the design for my cheap & cheerful Volt & Ammeter and put a link to it on my website. You can find the link here under Andrew's Volt & Ammeter.

If you need any more info, feel free to email me direct at info@trektable.com.au.

Happy tinkering!

FollowupID: 355953

Reply By: JohnN - Tuesday, Feb 08, 2005 at 09:57

Tuesday, Feb 08, 2005 at 09:57
Hi Mark

I just put one of these on my aux battery. Works well so far. Got it from Jaycar.


AnswerID: 97204

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