Battery monitor

Submitted: Tuesday, May 30, 2006 at 22:53
ThreadID: 34440 Views:3278 Replies:7 FollowUps:8
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I am new to all this battery stuff.
My wife and I and 2 kids are planning a 12 month trip around Oz and I envisage the batteries getting a heavy workout.
I have a dual battery system under the bonnet as well as another deep cycle battery in my camper trailer which is hooked up to the car via an andersen plug. Just wondering if others out there install a battery monitor in the dash to see the battery levels ? If so are there products which would show battery levels for my seperate batteries or am I really just needing to know the battery levels of my 2 deep cycle batteries ?
What is a common setup when it comes to battery monitors ?
Can you recommend any products ?

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Reply By: Member - Phil G (SA) - Tuesday, May 30, 2006 at 23:07

Tuesday, May 30, 2006 at 23:07
Easiest way I've found is to have a simple digital voltmeter hooked up to the second battery. It tells you the voltage to one decimal point, so you get an idea of how full or empty your battery is, and it will tell you that your second battery is getting recharged too.

As a rough, rough guide, your battery will be fully charged at about 12.8 volts (at rest). Might be half gone at 12.3 volts; Almost fully empty at say 11.9 volts.

When you are driving along, you'll know its being recharged at about 14 volts.

I use a combined volt/ temp gauge available from Jaycar electronics for about $35. I put a switch in line, so I can turn the meter off.


AnswerID: 175767

Follow Up By: markeaust - Wednesday, May 31, 2006 at 10:29

Wednesday, May 31, 2006 at 10:29

I also had one of these or similar for a few years and found, after checking with a quality digital multimeter, that it was as least 0.5v out across the spectrum. Also would often go blank for apparently no reason. Maybe I just got the dud one??

Would be worth doing the same with yours...



Ps New car now and have just ordered one of these...

Dearer, I know, but hopefully better
FollowupID: 431899

Follow Up By: Member - Phil G (SA) - Wednesday, May 31, 2006 at 11:36

Wednesday, May 31, 2006 at 11:36
Hi Mark,

Yeah, I've found the inaccuracy to be temp related - They overread by up to one volt in a really hot car on a summers day. When they are cool, I've found their accuracy to be acceptable for the purpose - about +/- 0.1volt. I carry a DMM with an adapter to measure as well.

I haven't had a problem with a blank screen, but was it really hot when it happened?

The upside is the Jaycar voltmeter uses very little power, so can be left on overnight or for days without an issue.

Sorry I can't get that link to work, but anything VDO makes sounds good.
FollowupID: 431917

Follow Up By: Hairy - Wednesday, May 31, 2006 at 19:45

Wednesday, May 31, 2006 at 19:45
Put a three way switch in with your voltmeter and you can switch between your two batteries and turn them off.
FollowupID: 432034

Reply By: Sand Man (SA) - Tuesday, May 30, 2006 at 23:10

Tuesday, May 30, 2006 at 23:10

Will be a little difficult to monitor the battery in the Camper, unless you do some re-wiring.

As far as the dual batteries in the vehicle are concerned, I have a simple solution.
(This requires a socket, preferably in the front of the vehicle, that is connected to the auxiliary battery, plus the original ciggy socket, connected to the primary)

Purchase a volt meter from Jaycar which has a ciggy plug on it and a velco backing.

To measure the voltage from either battery, simply plug into the corresponding socket. This will tell you when/if the alternator is charging, (should show about 14.1 - 14.2 volts) and the residual voltage level of each battery. (but accurately, only after vehicle has been at rest for several hours)

There are of course other solutions, but not as simple, or cheap.

Perhaps a cheap multi meter (or the volt meter mentioned above, removed from the vehicle) is the easiest solution to measure the Camper battery from time to time.

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AnswerID: 175768

Reply By: ACDC - Tuesday, May 30, 2006 at 23:37

Tuesday, May 30, 2006 at 23:37
Hi maxmcclo,
Have a look here ,i have one of these battery monitors and it works great certainly tells you more than just battery voltage.
AnswerID: 175774

Follow Up By: Wok - Wednesday, May 31, 2006 at 15:05

Wednesday, May 31, 2006 at 15:05
Thats sold by Sidewinder as well!...looks allright

FollowupID: 431953

Reply By: geocacher (djcache) - Tuesday, May 30, 2006 at 23:38

Tuesday, May 30, 2006 at 23:38
I made my own from a Dick Smith kit. I did make some mods to reduce the scale and improve the resolution and added a switch so I can switch between aux and main - all up mine cost me an hour and about $20 worth of bits. I find it really usefull and would recommend you do install something.

Mine's basically the same in function and operation to the Pirhana or Engel ones. (They are unfortunately over priced for what's in them and the fact that the design is common but that's life.)

Some like the Engel have the added advantage (one of the Pirhana does too) of being able to drive a relay to switch off devices at a preset "flat" voltage which is a good idea, especially if you are using gel cells which are permanently damaged if taken too low.

AnswerID: 175775

Reply By: Member - Bruce and Anne - Wednesday, May 31, 2006 at 07:20

Wednesday, May 31, 2006 at 07:20
The one I use is a multi purpose unit "time, date, inside and ouside temperature and volt meter" about $40 from Leading Edge Electronics. Velcro it on to the dash and run the cig plug to what ever battery you are monitoring. Has low voltage alarm and ice alarm which has been going off a bit here in the mornings (Nanango) 2 hours north west of Brisbane -2 today.
Cheers Bruce.
AnswerID: 175802

Follow Up By: GGtriton - Wednesday, May 31, 2006 at 17:13

Wednesday, May 31, 2006 at 17:13
i was wondering if you have a pic or a brand so i can chase up one of these. I have found Leading edges web site but it is not on their. Thanks

FollowupID: 431988

Follow Up By: Gramps (NSW) - Wednesday, May 31, 2006 at 17:22

Wednesday, May 31, 2006 at 17:22

That's the same one Jaycar sell. As I understand it, Leading Edge distribute Jaycar products. I've got one but have'nt 'permanently' installed it yet :))))
FollowupID: 431991

Follow Up By: Gramps (NSW) - Wednesday, May 31, 2006 at 17:28

Wednesday, May 31, 2006 at 17:28
Sorry GGtriton, I meant to include the brand name in my reply above. It's a "Made in China" jobbie (what a surprise) by "THERMO-tech"
FollowupID: 431993

Follow Up By: Member - Bruce and Anne - Thursday, Jun 01, 2006 at 07:14

Thursday, Jun 01, 2006 at 07:14
That it Al, sorry I dont know how to put photos on here yet.
Cheers Bruce
FollowupID: 432106

Reply By: Member - Craig D (SA) - Wednesday, May 31, 2006 at 09:34

Wednesday, May 31, 2006 at 09:34
I use a dual battery twin LED bargraph monitor purchased from Opposite Lock. I have wired it to both sides of the isolator but you could just tap off any of your two runs. I like this unit a lot as it has some neat functions - ability to turn off the displays independently; both displays have independent low voltage warning beepers, etc. It is easy to mount anywhere, light, and "resonably" priced, too.

Works for me, perhaps not for you.

AnswerID: 175838

Reply By: Truckster (Vic) - Wednesday, May 31, 2006 at 20:25

Wednesday, May 31, 2006 at 20:25
I looked yesterday at a new one that TJM are developing for twin batteries.

Looks REALLY good, although this proto is a little big.

Give Alan at Outback Accessories in Seaford a call.
AnswerID: 175988

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