DC-DC charger- which one?

**LandyAndy** · 20th May 2015, 09:10 PM

Originally Posted by RoverLander

I have been observing the voltage for the past several months.

It only drops down to 12.2v after the battery has been well charged and then if goes down to 12.2v when cruising or going up a hill. If you cruise constantly (without taking your foot of the accelerator) it can stay at 12.2v for quite a while. I have seen it last for at least 10 minutes while cruising on the M7. It will then jump up to 12.5v even though you are sill cruising.

As soon as you coast or go down a hill the voltage will jump up to anywhere between 13.1 and 14.9.

It is not completely consistent. I do the same trip everyday and I see 12.2v several times a day but not always under exactly the same circumstances. It never happens when coasting.

I wish I could taking a video so I can show you

Can anyone publish the content of the TSB. I don't know how to get TSB data.

From monitoring mine I can say what you have is a normally functioning charge system.
I have a ciggy lighter monitor.The smart charging system in these D4s only charges when it needs to and when economical to do so.So when you are off throttle yes the volts go way up,put your foot on the loud pedal and then they drop to the 12.6 or so.
Now,run a 80lt Engel on freeze,plus the headlights on,AC etc,etc,mine sits at 14.8V all the time.When its full it reverts to only charging at full voltage on the over-run.There may be a slight difference in monitoring at the ciggy lighter,but over several months of the same its close enough.
Mine falls within the vin numbers listed,and I do get that low battery warning when parked up in the shed for some time.
Service coming up,will see if there is any change with low battery warnings after the upgrade.
I have a one of Tims dual battery systems installed.Sofar has performed really well running the engel on 3 holiday trips.With the D2 I had to resort to plugging a Ctek in overnite.Havent had to with the D4.YET
Andrew

**SilvaD4** · 20th May 2015, 10:32 PM

Originally Posted by drivesafe

NOTE, one of the ways to deactivate the ECO STOP/START function, is to disconnect the negative lead on the STOP/START battery.

From what I have read about the eco stop starts systems (like that used on the Freelander II - Land Rover Launches Start-Stop Equipped Freelander 2 TD4_e In Australian Market | The Motor Report) is that they use the main cranking battery (i.e. there is no separate STOP/START battery)

**shanegtr** · 21st May 2015, 10:29 AM

There can't be that much of a fuel economy gain by doing these weird charging methods can there?

Tombie · 21st May 2015, 12:49 PM

Originally Posted by shanegtr

There can't be that much of a fuel economy gain by doing these weird charging methods can there?

Predominantly European Emissions... Where the difference of 0.005% can mean a significant cost saving to the owner...

**drivesafe** · 21st May 2015, 06:11 PM

Originally Posted by SilvaD4

From what I have read about the eco stop starts systems (like that used on the Freelander II - Land Rover Launches Start-Stop Equipped Freelander 2 TD4_e In Australian Market | The Motor Report) is that they use the main cranking battery (i.e. there is no separate STOP/START battery)

Hi Silva, I know nothing of the setup in a Freelander, but the Eco STOP/START system in the D4 is located in the auxiliary battery box on the driver's side of the engine bay.

In with the electronics is a small battery. The setup is very similar ( if not the same ) as in the new RRS.

**Mungus** · 21st May 2015, 07:08 PM

In an D4 Stop/Start vehicle, the Dual Battery system isolates all power supply to sensitive electrical components/systems which may be affected by low voltage from the primary battery due to the Tandem Solenoid Starter motor operation and supplies them with power from the secondary battery when an engine start is in progress. The Primary battery is used exclusively to supply the TSS motor and essential power required for engine starting. The Power Supply Distribution Box uses two banks of MOSFET's to change the supply into two separate circuits when an Eco Start is required.

**drivesafe** · 24th May 2015, 09:18 AM

Originally Posted by Mungus

In an D4 Stop/Start vehicle, the Dual Battery system isolates all power supply to sensitive electrical components/systems which may be affected by low voltage from the primary battery due to the Tandem Solenoid Starter motor operation and supplies them with power from the secondary battery when an engine start is in progress.

This would probably explain why the STOP/START function is deactivated when the negative lead is removed from the STOP/START battery.

The system can,t find the second battery so rather than risk sensitive system being interrupted, the STOP/START function is deactivated.

**Fluids** · 24th May 2015, 09:50 AM

Our Impreza has the STOP/START feature (feature!!??) ... also has a "disable" button on the dash. Why not do the same for the D4 ? No traffic lights were we live so the S/S feature can get a bit annoying ... that said, before you can get the clutch pedal to the floor the engine has restarted ... it's very quick.

The Impreza trip computer has a start/stop time activated display ... 2.5Hrs each way trip to Sydney saves us approx' 20-25min each way ... that's almost 1Hr saved on a 5Hr trip ... 20% ... not to be sneezed at ...

... however, me thinks there's a corresponding reduced life of the starting battery and starter motor ... time will tell.

Car only uses one battery (cranking).

**Mungus** · 24th May 2015, 10:52 AM

Originally Posted by Fluids

The Impreza trip computer has a start/stop time activated display ... 2.5Hrs each way trip to Sydney saves us approx' 20-25min each way ... that's almost 1Hr saved on a 5Hr trip ... 20% ... not to be sneezed at ...

Car only uses one battery (cranking).

That's a cool function. Whilst it's not actually 20% saving of fuel usage, it is still 40-50minutes less idle.

**drivesafe** · 24th May 2015, 12:11 PM

I'm a bit sus about some of the claims about how much fuel is saved with the STOP/START function.

To have the motor stopped for up to 20% of a trip ( Subaru add ), you would be sitting at traffic lights or in traffic jams for a hell of a long time.

Then once out on the open road, there would be no advantage.

One thing I do like about the Subaru version of the STOP/START operation is that you can turn it off at any time.

A few makes now have STOP/START operation, but they are either permanent or can only be deactivated when you first start your trip.

I noticed that some of the VWs have two switches, one to deactivate the STOP/START for that trip and one to deactivate the function permenately.

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