Discovery 2 Alternator and Battery Monitor Modification.

[Stainless]

Although our Discovery 2s have plenty of electronics, I miss not having a Voltmeter or Ammeter, as they can give advanced warning of developing electrical problems.

I added an LED 12 Volt Power Monitor to an existing blank lower dashboard switch plate (FBV000090PUY), using the Velleman 12 volt Car Battery Monitor Kit MK189.

Alternately a blank upper binnacle switch plate (FBV000080PUY) may be used, if no vacant / blank lower dashboard switch is available. Both blank switch bodies are the same, but with different clip-on front panels.

Drill a 3mm diameter hole in the centre of the blank switch plate and fitted the finished kit into the switch plate body, which is a perfect fit, make sure you cut the 3 LED legs to the correct length.

Take an Ignition Switched 12 volt power feed from the Passenger Compartment Fuse Box, connecting into the lowest relay socket using male spade connectors (R211 V8 Engine Ignition Coil Relay).

(This relay is missing on TD5 D2s and so makes connecting to the vehicle power rails easy, Earth to relay connection pin 86, and +12 volt to relay connection pin 85), protected by Fuse F24 10 Amps.

On V8 models, any other dashboard power connection points will do. The dashboard photographs also show the Land Rover additional switch housing AWR3330LNF, which replaces the Ash or Coin Trays.

The Kit Bi-Colour LED shows a Steady Green for Battery OK. Flashing Green for Battery charging. Steady Red for Battery low, and Flashing Red for Battery overcharging.

Although the 3mm diameter Bi-colour LED looks bright in the photograph, it is not too bright at night, matching the green background dashboard illumination.

It is accurate, as if I switch on both front and rear heated screens, together with headlights at engine tick-over, the LED changes from flashing Green to steady Red.

If I raise the revs very slightly above tick-over, the LED changes to steady Green, and then back to flashing Green. Luckily I have not seen a flashing Red display yet (battery over-charging).

[drivesafe]

Hi Stainless and that looks good but you are not actually reading either battery or alternator voltage.

You are reading fuse box voltage and while you would think it was the same as the voltage at the battery, it is commonplace to get a voltage reading 1 volt or more below the battery’s actual voltage.

This difference in voltages is caused by any load being powered through the fuse box and all those items you turned on to test the unit, are all sourced through your fuse box.

If you carry out the test again, first measure the voltage at your battery, turn all those items on again and then test the voltage at your battery while everything is turned on.

If there is actually any voltage drop, it will be marginal at best.

To get an accurate voltage reading you need to get it at the battery itself and you might be able to modify your kit to do that.

[Pedro_The_Swift]

Hey Tim,,
is there a safe way of reading amps these days?
ie; no cables in the cab?

[drivesafe]

Hi Pedro and yes there is.

There are a few devices that use a shunt, which is placed where ever you want to get your current reading from and then you just run some thin wire into the cab to the device and job done.

A lot safer and much easier to install instead of running huge cables into the cab, to an old style amp meter.

[gavinwibrow]

Hi Pedro and yes there is.

There are a few devices that use a shunt, which is placed where ever you want to get your current reading from and then you just run some thin wire into the cab to the device and job done.

A lot safer and much easier to install instead of running huge cables into the cab, to an old style amp meter.
Hi Drivesafe. Is there an Oz alarm and monitoring kit (maybe similar to or better than this one? http://www.lrautomotive.com.au/contents/en-us/d702.html (http://www.lrautomotive.com.au/contents/en-us/d702.html) ) that will do as you suggest?

[Stainless]

drivesafe The mod was not intended to display an accurate voltage reading, hence I was not concerned with the voltage drop from the battery. The idea was just to detect any charging problems as quickly as possible.

[Tombie]

Hey Tim,,
is there a safe way of reading amps these days?
ie; no cables in the cab?

Yeah... And mine goes to 11 :angel:

https://www.aulro.com/afvb/

[drivesafe]

drivesafe The mod was not intended to display an accurate voltage reading, hence I was not concerned with the voltage drop from the battery. The idea was just to detect any charging problems as quickly as possible.

Hi Stainless, I wasn’t having a go at you, just letting you know that the voltage differences can be so great, that the device would be next to useless.

There is a youtube clip of a guy showing the voltage readout on his BMW.

He brings the display before he puts the key in and it shows 11v.

Then he turns the key to the ON position and the display shows 10.5v.

He then starts the motor.

There is no way he could have started his motor if the battery voltage was 10.5v, that’s a dead flat battery. He couldn’t have ever got the starter motor to do more than click, if that.

All he was getting was dash voltage not battery voltage.

My point is, the device will not be of real benefit if it’s not getting actual battery voltage readings.

[drivesafe]

Hi Drivesafe. Is there an Oz alarm and monitoring kit (maybe similar to or better than this one? http://www.lrautomotive.com.au/contents/en-us/d702.html (http://www.lrautomotive.com.au/contents/en-us/d702.html) ) that will do as you suggest?

Hi Gavin, and there use to be kits something like that a good few years back but to be honest, I have never bothered pursuing them because of the high costs.

[Fluids]

Hey Tim,,
is there a safe way of reading amps these days?
ie; no cables in the cab?


Yeah... And mine goes to 11 :angel:

http://www.metalinsider.net/site/wp-content/uploads/2011/11/SpinalTap-11.jpg


I'll see your 11 and raise you ...

.... 'cause my little tweed baby goes to .... 12 ! :twisted:

https://www.aulro.com/afvb/images/imported/2011/11/298.jpg

... sorry for the hijack :)

[Stainless]

Here are the voltage drop readings between the vehicle battery terminals and the connector in the dashboard monitor modification. The measurements were taken using two calibrated 4 1/2 digit digital voltmeters, which showed identical voltages as each other, but were still changed over for a second test procedure to eliminate any inaccuracies.

Voltage measurement points-------------Battery-----Monitor----Voltage drop
Ignition on, engine off:----------------------11.87v------11.82v-------0.05v
Ignition on, engine running:---------------14.52v------14.48v-------0.04v
Engine running, heated screens:-------14.22v------14.17v-------0.05v
Engine running, heated screens +
headlights + heated seats:---------------12.97v-------12.92v------0.05v
Various vehicle electrical devices:----14.18v-------14.12v------0.06v
-----------------------------------------------------14.2v---------14.14v------0.06v
-----------------------------------------------------13.62v-------13.58v------0.04v

The maximum measured voltage drop was 0.06v. I think a paltry 60mv voltage drop is perfectly acceptable. A direct connection from the dashboard monitor modification connector to the vehicle battery terminals using 20-amp, 75/0.19mm, 2.12-sq/mm-CSA cable gave exactly the same voltage drop.

[drivesafe]

Sorry stainless, but you must be doing something wrong because you should not have had ANY VOLTAGE DROP if you wired direct to the battery.

This is because a volt meter does not draw current, so there is no way you should have registered any difference in the voltage reading at the battery and at the meter in the dash if you had run a dedicated set of wires from the dash mounted meter to the battery.

The use of thick 20 amp wire achieves absolutely nothing, you can use the thinnest figure 8 speaker wire and still get the exact same voltage reading at the battery and at the end of the speaker wire.

Again, you must be doing something wrong.

[Stainless]

Returning to your original point, ( your 1 volt or more, against my 0.06 volt, voltage drop) comparing your own tests with my voltage drop table, what voltage drop did you actually measure between the vehicle battery terminals and the photographed relay terminals in the internal cabin fuse panel ?

[drivesafe]

Hi stainless, and I’ve been working on vehicle electrics for over thirty years and I have never seen a vehicle that did not get at least a 0.5v voltage drop at the dash wiring and 1 volt is common place.

Won’t comment further on your voltage readings, but when I had my D2, it had around a 1 volt drop at the dash wiring once you turn a few things on.

I’ll leave it at that.

[Stainless]

Likewise, I have spent over 40 of my 60 years in electro-mechanical engineering, and try to never criticize other people, unless I have had personal experience of the actual subject being discussed.

If you repeat my test of actually measuring the voltage drop between the TD5 Discovery 2 battery terminals and the internal cabin fuse panel (not the dash wiring - wherever that might be), you will get a voltage drop reading of around 0.06 volts.

Make sure there are no bad battery feed to fuse panel connections on your test D2 TD5 vehicle, actually do the exact voltage drop test in question, take the measurements, and I will then accept your apology.

Talking of apologies, I am very surprised that thread hijacking ( as on page 1 of this thread ) is allowed on this otherwise popular and excellent Land Rover Forum.

[clubagreenie]

As a comparison just (well earlier) went and checked the figures against mine and as follows.

Voltage measurement points-------------Voltage drop---Battery vs fuse box
Ignition on, engine off:--------------------------0.92v
Ignition on, engine running:---------------------0.78v
Engine running, heated screen (rear only):-----0.96v
Engine running, heated screens + headlights:-- 0.98v

[Stainless]

Photograph 1. (On previous comment) both DVMs connected across Vehicle Battery Terminals.
Photograph 2. Drivers side DVM connected to Vehicle Battery Terminals.
Photograph 3. Passenger side DVM connected to Dashboard Monitor Mod Connector.
Photograph 4. Ignition turned on without engine.
Photograph 5. Engine running.
Photograph 6. Engine running with Headlights Main Beam.

[drivesafe]

Stainless, you may have found a wire that has nothing connected to it, but as pointed out, repeatedly now, you should never use dash ( fuse box ) wiring to try to get accurate battery/alternator voltage.

It is NOT good practice to source your voltage readings anywhere but at the battery itself.

If anyone has a D2, try your luck, but anybody interested in getting accurate battery voltage readings, no matter what type of vehicle it is, go to the battery terminals to get your voltage source from.