Battery Monitors

Hi Toy,
If you run the auxilliary battery down to nothing often enough you'll bugger it quick smart.

Now to monitoring, One of the quickest and cheapest methods when you are stationary is a $5 Dick Smith, Jaycar or Bunnings multimeter. Just check the voltage and if it's down to say 11.5 volts give it a charge.

The meter has other uses around the vehicle too.

A word of safety, I'd be reluctant to wave a $5 meter anywhere near 240 volts.

Geoff

Hi Toytruck,
Have a look at the Opposite Lock website, they have a unit called Chargemaster, Battery isolator and monitor for both batteries that all just plugs together. The monitor is good in the way that it has LED monitor for both batteries and if you do have a failure on the start battery it has a button override to bring the secondary battery in to start the vehicle.
Cheers RosscoH

I used to have a monitor in the cab which showed me my charge voltage (off the alternator) - I now have one at the back of the car built into the drawers (frame) - best thing I've ever done - every time I get a beer I can see it's "OK" or "not OK" - I'm on top of issues much quicker than before when I had to "go to the cab to look"

In al fairness, to be able to get anywhere near an accurate reading of the state of your batteries, you need to spend at least $500 as a stating price to get a genuine effective battery monitor.

These will be able to give you a comparatively accurate indication of your batteries, even when the motor is running.

The cheaper ones are no more advantage to you than the multi meters suggested by Geoff ( Newcastle ) and as Geoff also suggested, a multi meter has many other useful uses around your vehicle.

But if you don’t mind spending a bit of money, for around the same price as many of these next to useless elcheapo monitors, you can buy a clamp meter ( also known as a Tong meter ).

These clamp meters not only measure voltage but also measure current but unlike normal multi meters that have to be physically wired in series in the cable that is going to be measured, Clamp meters simply wrap around the cable and give an immediate reading without even touching the the cable.

Furthermore unlike standard multi meters that have a maximum current handling capacity of 10 amp ( some can handle slightly higher ) clamp meters can measure hundreds of amps and some go to over a thousand amps.

This makes clamp meters ideal for automotive use. Nothing like being able to measure full alternator current output without having to cut cables.

Cheers

I put a VDO voltmeter wired up to the 2nd battery.
The pajero already has a a voltmeter for the 1st battery.
Also put a switch on the VDO as it does allow some voltage drop over a day or 2.

Just buy a cheap volt metre from jaycar or someone. You'd be suprised how differently your draw on the aux will be in different weather conditions. On a hot day at the beach you can easily wipe out a good 100amp hour battery with the fridg if it's set cold enough. In winter the battery will discharge because of the cold. Do you run your stereo? How do you know what the type of music your playing is doing? Basy type music will draw more than other types, mines only a stock stereo and it can draw 6 amps easily.

When you go for a run have you completley recharged your battery? My guess would be no unless you're going for a few hours at least.

Just go the guage and be done with it, it's better to know than not to IMHO.

I monitor second battery voltage which tells me
- that the isolator is working and when it kicks in,
- that the alternator and regulator are working
- and will give you a ball park idea of capacity (once you get a feel for it)

I don't go on holidays to spend my time playing with electronics. And my Jaycar $40 LCD voltage meter has been accurate to with 0.1 volt (except of you sit it in the sun), and only draws about 10 milliamps.

I've put dual batteries in my old Troopy & I recently did the same to my Prado. As a battery monitor, I've used a "Dick Smith 12V battery tester", which has 6 different coloured LEDs to show the state of charge. ( It cost les than $20), and IMHO it's great.
I opened up the tester and fitted a miniature slide switch inside it to which I wired to both batteries. I just slide the switch to select either battery.
The tester is affixed to the centre gear shift console, in the groove under the hand brake lever, with double sided adhesive tape. Sparky.

Hi Toytruck

You have many options.

Price is a factor but a 2 way switch is simple option to check voltage on both batteries. You would not be able to do a load test on the starting battery when using the LCD one unless you use a heavy duty relay.

We are designing a new range of monitors and hope to have them in by Easter, these will monitor both batteries at the same time and give live feedback to the user. We feel that with our new range of micro computer controlled isolators on the way we need a better monitor.

Our existing range is as follows and are available from other outlets not just sidewinder.com.au . TJM stock the LCD ones, the analogue ones are also stocked by Arrid and Alzone and the LED one is a Projecta product available at most Repco stores.

1) LCD digital volt meter $150.00

2) Analogue volt meter $29.95

3) Simple LED monitor $30.00







Regards

Derek

In answer to your original questions, you probably don't need to monitor both batts if you are only using the aux when stopped somewhere, but as already said a form of checking the aux batt is probably needed.

I don't like the analogue meters as they are not accurate enough ( is the batt 12.4 or really 12.7 ??? )

And $150 for a digital is a little steep when you can buy a $25 multimeter.

I tried a $30 job from jaycar ( digital meter, clock, timer thingy ) which is pretty much useless as it doesn't read the same as my multimeter 5 times out of ten !! And can be out as much as .5V

But even with a meter of some sort, the best approach is to charge the batts at every chance you get ( even daily if it's no trouble )

I've installed (with a switch to change between batteries) on of these from Jayco (Cat No XC0118). Unlike another poster here I've found that it is within + or - 0.1Volts of my multimeter and seems to work well.