Thread: D3 Ammeter Options?

The link below is to the Traxide people, (drivesafe on the forum), who make a pretty good dual battery interface for the 3 and 4.

Drivesafe at least understands which direction power is moving from the main starting battery and where it is coming from or going to, and more importantly, why and how. That brings up another question - is that what you were thinking of monitoring?

I think perhaps you were wondering what current the alternator is putting out at any given time or were you wondering what current the vehicle systems were drawing or - well it keeps on going, particularly with multiple batteries.

As such, the solution to what you may be asking is not easy to answer any longer. When a vehicle electrical system consisted of a generator, a battery, and a load, (the vehicle), it was not too hard to insert something somewhere to at least tell you what the battery was doing, charging or discharging, and that would mean something. Now it is not so easy.

My own view is that if you want to monitor alternator output, taking a measure of field voltage used to give a pretty good indication of load, (higher field volts, the harder the alternator was working). With these new alternators, I do not even know it they have what used to be called field voltage. I have attached the battery / alternator wiring diagram for an LR3 and the only wire identifier word I understand is B+ and maybe Batt Sense coming off a 5 amp fuse that I presume provides 12VDC power to what I used to call the Field, but somehow I think it is called something else now.

I even see a couple of locations where I "suppose" one could insert an old fashioned shunt and monitor amps in or out of the battery or alternatively, amps out of the alternator, but somehow the term "old fashioned" bothers me. I figure some Can Bus monitoring system would probably pick up on the shunt and throw a fit - well drop the 3 to the stops as that seems to be the first reaction to any concern.

Anyway, it may be simple and I may be making a too big deal of it, but the word "obvious" and my word "suppose" does bother me. The question is an interesting one however.

D3

I don't believe Scangauge gives a reading of amps - does voltage though. Scan gauge is cheap at $160 especially as no modifications are required to connect and mount it.

Surely the voltage readout from a scangauge or even a basic voltmeter combined with the charge light on the dash is all you would need.

Garry

Originally Posted by garrycol

I don't believe ScanGauge gives a reading of amps - does voltage though. Scan gauge is cheap at $160 especially as no modifications are required to connect and mount it.

Surely the voltage readout from a ScanGauge or even a basic voltmeter combined with the charge light on the dash is all you would need. Garry

I have the ScanGauge II installed and yes, it does give voltage, (no amp readings), but from just where the voltage reading is taken, I am not certain. The ScanGauge is connected to the OBD port, but from where the OBD sources its voltage, I do not know.

My guess is that it gives alternator output voltage when the engine is running. The voltage numbers seem to suggest that. Readings vary from a high of 15.0 to about 12.4 volts, but mostly run about 13.9 volts.

These numbers seem to me like alternator output voltage rather than battery or buss voltage.

a simple dedicated clamp on amps meter can be obtained from Jaycar in kit form.

as it reads in both directions clamp it to the earth lead of the battery and it'll tell you how much is going out or in at any given time.

Originally Posted by bbyer

I have attached the battery / alternator wiring diagram for an LR3 and the only wire identifier word I understand is B+ and maybe Batt Sense coming off a 5 amp fuse that I presume provides 12VDC power to what I used to call the Field, but somehow I think it is called something else now.

D3

Thanks a bunch for the PDF... very helpful! I did look at Traxide site actually while on the prowl for options thinking their dual kit may provide a dual excuse for purchasing one.

I'll check out the Scangauge option as I didn't realize they were that price... interesting.

The Jaycar kits I'll have a look at too as we have trade accounts with them... you never know.

The voltage output is I think not a 'real' help as these type of alternators I believe have constant output at all revolutions so I'd expect it only fluctuate a little while actual current draw is the real number I'd like to see and which direction it's going in... be useful to see how quick the battery comes back up after a start etc for one thing.

I've had an alternator die now and the battery has been brought back to life a couple of times now (actually has an RAA 600CCA in it... huh?) and I can see a real need to be on top of the electrics of the D3 especially when off the black stuff.

Interesting comments... thanks.

Originally Posted by Blknight.aus

a simple dedicated clamp on amps meter can be obtained from Jaycar in kit form.

Hi Dave, do you have a link to the kit at Jaycar. I’ve had a look through their cattle-dog and not found it.

I’ve been looking for high current non intrusive current monitors for years and never found anything that didn’t need installing in-line to get a reading.

I use a clamp meter but have you ever tried taking a current measurement with the bonnet up, hanging over the grill doing a hundred kph down the freeway. Hell does it blow a breeze up the kilt, and the wife finds it very difficult holding on with only one hand.

Seriously, I have come across a few AC clamps that can be fixed over a cable and a normal multi meter can be used remotely to get measurements but I have not come across any decent DC remote clamps.

The D4’s 140 amp alt/gen is bad enough but the D4’s 180 alt/gen makes it next to impossible to get an idea of what is going on.

Try ABR Sidewinder. They have an aircraft setup available if your budget will stretch to it. ( $300.00 plus ) Looks the goods. I cannot comment as to how good, bad or otherwise.

If you are looking for a simple setup, Wurth, SnapOn and I believe several other tool suppliers, make a plug in ampmeter for a single fuse draw. ( remove the fuse, plug in the tool ) I have the Wurth tool. Not really suitable for remote mounting though.

Ammeter shunts available:

150 Amp 50mV Ammeter Shunt | eBay

Suggested to fit into the battery earth cable.