Thread: Discovery 2 Alternator and Battery Monitor Modification.

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.

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

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.

Originally Posted by 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.

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 ) that will do as you suggest?

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.

Originally Posted by Pedro_The_Swift

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

Yeah... And mine goes to 11

Originally Posted by 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.

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.

Originally Posted by gavinwibrow

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 ) 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.