In Cabin Voltmeters

Submitted: Tuesday, Mar 01, 2005 at 18:31
ThreadID: 20882 Views:2329 Replies:7 FollowUps:9
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Hi All,

As some of you may have read I have recently fitted a fridge in my 4by and at the moment it's in there 24/7. What I would like is an in car voltmeter (probably digital) just so I can keep an eye on the second battery level to get an idea of how it is after a weekend of not much driving, how long it needs to run to recharge fully etc etc I assume it only needs to be connected to the second battery? as that is the only one with "hot" wires so to speak.

are there any voltmeters you guys recomend? or any you don't?

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Reply By: Member - Ivan (ACT) - Tuesday, Mar 01, 2005 at 19:29

Tuesday, Mar 01, 2005 at 19:29

Hit the archives mate - this has been done to death a couple of times recently - if you still need more, hit us with it ;-)
AnswerID: 100709

Follow Up By: Member - Browny (VIC) - Tuesday, Mar 01, 2005 at 20:33

Tuesday, Mar 01, 2005 at 20:33

Cheers Mate, I did have a go there first, I typed in Voltmeters and it came back zilch! I couldn't think of anything else to type, I'll try again with other options and see how I go.

FollowupID: 358857

Reply By: Member - Jimbo (VIC) - Tuesday, Mar 01, 2005 at 20:41

Tuesday, Mar 01, 2005 at 20:41

Get a cheap voltmeter, $10 at Supercheap or similar. Buy two 'banana" plugs from Smithies and attach two wires to the plugs that run to your batt. Put the banana plugs into the holes on the volt meter and switch it on from time to time to check the voltage.

Cheap, but effective.


AnswerID: 100715

Follow Up By: Member - Browny (VIC) - Wednesday, Mar 02, 2005 at 15:48

Wednesday, Mar 02, 2005 at 15:48
Cheers Jimbo
FollowupID: 358932

Reply By: AdrianLR - Tuesday, Mar 01, 2005 at 21:33

Tuesday, Mar 01, 2005 at 21:33
Have a look at this one at Jaycar - has voltage and temperature:

STOCK-CODE: XC0116 RRP: $39.95

Car Voltage Meter / In-Out Thermometer / Clock

A bit pricey but will also tell you what the fridge is doing.

AnswerID: 100719

Follow Up By: Member - Roachie (SA) - Tuesday, Mar 01, 2005 at 22:09

Tuesday, Mar 01, 2005 at 22:09
Yep, that's the one I've got. I think mine has some dud parts, cos it doesn't work as well as it should, but it sort of does the job. I remember posting a response about this a few weeks ago; so here goes again:

I've lengthened the remote temp sensor (cut it and spliced in some fine cable) so I can have it dash-mounted and the sensor is in the fridge.

I cut off the cigi plug and hard wired it to some other gear on the dash that gets power from 2nd battery. It's supposed to have a blue backlight on whenever it has power (full-time in my case, even when motor is off), but that feature works only when it feels like it.

It has a buzzer that goes off when power goes below a certain level (I think it was 10.5v). But on mine it beeped and farted so much that i pulled the back off it and snipped the wires to the speaker.

The clock didn't keep very good time. It runs off 2 button-type batteries, so I chucked them (don't need clock anyway).

There are 2 read-outs available and 3 things to monitor (inside temp, outside temp, voltage). There is a few buttons you can push to choose various read-outs. I prefer to see the fridge temp and volts, but sometimes it just changes itself to whatever it likes!

Yesterday, the temp in the truck was BLOODY hot when I knocked off work. The whole screen had gone black due to the heat, but it came back ok once it cooled down.

Hope this long-winded response helps a bit.
FollowupID: 358870

Follow Up By: Member - Browny (VIC) - Wednesday, Mar 02, 2005 at 15:54

Wednesday, Mar 02, 2005 at 15:54

Thanks mate sounds something like I'm after, the temp guage is a "bonus" to I guess.



Thanks mate, much appreciated info.

FollowupID: 358933

Follow Up By: Member - Jeff M (WA) - Wednesday, Mar 02, 2005 at 16:49

Wednesday, Mar 02, 2005 at 16:49
I've got the same, works fantastic! Goes a little funny when the interior temp get's over 60c but comes good again after the air con is on for a while.
FollowupID: 358937

Follow Up By: Member - Rick (S.A.) - Wednesday, Mar 02, 2005 at 22:24

Wednesday, Mar 02, 2005 at 22:24
Me 2, Roachie.

Sensor location seems to be important. Mine read 55 degrees ambient , when located under bull bar, in Robe 2 winters ago. I re-located the sensor to inside the doorwell on RHS A pillar, up about top hinge level. Soon after, it started going spazzo. Any numeral could pop up, inside/outside, but close enough to make me wonder what was wot!

Battery volts never seemed to be dicky, even referenced against a hand held voltmeter

Hot days it crashed. Cool days, I was always thinking that it must be wrong. Eventually got sick of it & binned it. Blew $ 40 there- but who cares, it's only money.

Now I am happier.

I can tell if it's hot - I sweat.
I can tell if its fine - look out for rain or clouds
I can tell if the air temp is low - open the window

Moral of the story - like with most 'gadgets' - I have come to realise that less is more.

FollowupID: 358975

Follow Up By: Member - JohnR (Vic) - Wednesday, Mar 02, 2005 at 22:35

Wednesday, Mar 02, 2005 at 22:35
Me too Roachie, before the trip away though the clock carked it which was a pity as it was easy to be seen from the navigators seat. Hope that it can be replaced by Jaycar, but the hour plus that it could take to get the wiring done I don't know it's best to keep the nav informed anyway - it may be me. Heather warned me the clock is on the CDMA anyway.

I set the outside temp sensor in the snorkel to check the important inlet temps - it would warn me of ice the info tells me......
FollowupID: 358976

Follow Up By: Member - Jeff M (WA) - Thursday, Mar 03, 2005 at 11:31

Thursday, Mar 03, 2005 at 11:31
I've got my sensor siliconed on the bottom of the snorkel Air Ram. Give's me the same readins my Multimeter's temp sensor gives me. Inside temp is a little screwy as it's glued to the dash above the stereo so when the music is cranked it gets heat rising from the stereo.
Volt = perfect.
Clock has never faulted.

We don't have that much COLD weather in Perth so maybe that's why mine has not faulted like you guys did. The screen does go Black when it's REALLY hot inside (parked at the beach on a 40+c day) but my Multimeter does the same thing if I leave it out in the sun so I don't think it's actually a fault as such.

Oh well, mine works so Nah nah na nah naaa! ;-) LOL
FollowupID: 359007

Reply By: Andrew from TrekTable - Tuesday, Mar 01, 2005 at 22:51

Tuesday, Mar 01, 2005 at 22:51

Check out post # 20130 and #20336. In 20336 I posted a link to a simple Amp & Voltmeter which may interest you.

My text in that post said "Just recently I embarked on a project to build a combined volt and AMMETER. Basically I wanted to measure battery volts to determine battery state, plus also be able to measure current into & outof my 2nd battery. Problem is, most AMMETERs are symmetrical (ie -1000A to +100A) but I wanted to be able to measure input current (approx 80A) but also output current (approx 4A) and a symmetrical meter was too inaccurate at low ranges. So I built a cheap & cheerful Volt & Amp meter. I discussed this a few days ago on a different thread and had abit of interest so I drew it up & posted a link.

You can find my cheap & cheerful Volt & Amp meter herehere. If you want to learn abit about shunts & meters, it's not a bad project to begin with. "

If this info helps and you want more info, feel free to email me.

AnswerID: 100727

Reply By: The Rambler - Wednesday, Mar 02, 2005 at 00:13

Wednesday, Mar 02, 2005 at 00:13
Iwas glad you posted that honest response as I nearly bought that same thing at the Engel agent here in Perth--Ithink he wanted $50 bit I will give it a miss now.
AnswerID: 100749

Reply By: old-plodder - Wednesday, Mar 02, 2005 at 09:26

Wednesday, Mar 02, 2005 at 09:26
I must be crazy, or spent too much money, which would be unusual since my wife is always complaining how stingy I am, but I bought a standard VDO volt meter to mount on the dash, and hooked it up across the terminals of the battery. Is this too simple? Interesting to watch the voltmeter for the main battery and the 2nd battery, and how the rotronics switches current between the two.

If you want a cheap cover (pod) for the 2" gauge, use two caps off some black spary cans (or pick another colour). Cut the bottom off one so it will mount at the front of the guage, the other for the rear.

Only problem I have found is that there is some current draw and the battery drops from 12.8V to 12.5V over night. So I put a switch in the circuit, which hopefully doesn't have too much voltage drop.
AnswerID: 100767

Follow Up By: Member - Browny (VIC) - Wednesday, Mar 02, 2005 at 16:15

Wednesday, Mar 02, 2005 at 16:15

Thanks mate, more food for thought.

FollowupID: 358934

Reply By: B0XER - Wednesday, Mar 02, 2005 at 09:40

Wednesday, Mar 02, 2005 at 09:40

Must be a dud mate, as I run the same unit and have had nothing but success with it. I cut the cig plug off it and wired it in parallel inside the fridge cig plug and then velcro'd it to the fridge. Its great its backlit all the time so I can peer through the back window of my car at night and see fridge temp and batt volts

AnswerID: 100771

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