Thread: Discovery 4 "smart" charging system.

The voltages you are getting over the time period seem normal and what i would expect from D4. I suggest either drive the vehicle more or add a solar panel to keep the battry charged.
I am looking for a flexible stick on solar panel for my D3 to keep its battery fully charged. i have heard that a solar panel can be put inside a window and still produce useful current but i have not tried this yet.

Ian
Bittern

Hi Ian,
Thanks for the response.
I agree the symptoms are normal.
I'm wondering if we can change the behaviour of the Battery Monitoring Sensor so that it does not discharge a fully charged battery to 80% SOC.
I have a hookup from the van to use its solar to maintain the start battery, and via the AUX battery management system the Aux battery.
This was suggested by Tim from Traxide in 2018 in a post.
When I disconnect the van the Battery Monitoring Sensor does its thing and drops the start battery to 80%SOC over 1-2 days. This is what I find irritating.
If I leave the van connected the car tries to discharge its batteries as well.
Charging at home is fine but when I am away it irritates me I have to take these charging precautions. Hence my posted questions.
I have seen in a VW that its start/stop can be disabled (and its smart charge) by simply disconnecting the sensor connector. This results in a Battery Monitoring Sensor failure error and dash battery light in the D4. Even disconnecting the 12v sense wire from it, leaving the LIN bus wire gives the same result.
So, what other options are available?
Thanks all.

GIL

I also have a fridge in the D4 which runs off a Traxide SC80 system with two 55aH batteries.
In the past, I have noticed that the D4 was not charging sometimes after being stationary for a couple of days with the fridge running. A couple of stop/starts later all returned to normal.
To get around the battery management system I leave the D4 connected to the van or I connect to a 200W solar panel which lives on the roof bars.
I keep an eye on the Generator/alternator set point value in my GAP tool to see what the system is requiring of the alternator.

As a side note, Running a DC2DC to charge LifePO4 batteries in my van can create some interestingly high numbers around the alternator current & set point if the D4's dual battery system is low on charge. I have resorted to disconnecting the DC2DC until the D4 batteries are reasonably charged & the alternator current drops to 70 amps.

Hi Milton477,

Thanks for your input.
I also run a fridge in the back of the D4 and I have a little cigarette lighter socket voltage display unit connected as well. Also a 2nd one on the car accessories circuit so I can monitor both start and aux batteries.
I have not noticed a delay in charging other than the 2-4 seconds after a engine start before the voltage starts climbing to 14.7v.
With the van connected to the start battery both batteries stay charged but the "smart" system in the D4 can try to discharge ALL batteries in an attempt to ascertain battery SOC and this aspect is what I am curious to investigate.
If it is possible to disable the Battery Monitoring Sensor in the D4 MAYBE it will not discharge my fully charged batteries so quickly.
I am also not really surprised by the large current you are seeing as the alternator is , I think, 180A.

GIL

Originally Posted by Milton477

Running a DC2DC to charge LifePO4 batteries in my van can create some interestingly high numbers around the alternator current & set point if the D4's dual battery system is low on charge. I have resorted to disconnecting the DC2DC until the D4 batteries are reasonably charged & the alternator current drops to 70 amps.

Hi Milton, what size DC/DC unit do you have?

Originally Posted by GIL

Hi Folks,
A long post. My apologies first up.

A questioning of the "smart" charging of the Disco 4.

I have been concerned with the charging/battery monitoring regime of my D4 (2013 TDV6 8-spd).
I seem to have no trouble with the "smart" charging aspect as I tow a caravan and run with headlights ON which seems to give me fully charged batteries. I have a Piranha dual battery management system fitted which separates the two batteries at 12.8v.

The issue I see is that when stopped and parked, the battery monitoring system flattens the start battery to around 12.4v in 1-2 days, where it then stays for another 2-4 days before slowly discharging to 12.0v or slightly below after typically 2 to 2 1/2 weeks.
At this point a 'Low battery. Start the car.' message could be displayed.

I have seen a Jaguar writeup indicating the battery monitoring system flattens the start battery to around 80% state of charge (12.4v) to get an understanding of the condition of the battery, so it can then tailor the "smart" charging of the battery and provide headroom for the charge resulting from regenerative braking, when the system ramps up the alternator output on vehicle deceleration.

Nanocoms Genesis indicates there is a CCF setting where the Battery Monitoring Sensor can be set to 'without Battery Monitoring Sensor'.
Has anyone tried this?
Does this setting then command the ECU to default to standard charging profile at (I presume) around 13.8v?

Hi Gil, while I have no idea how the Jag system works, with the disco4s, the BMS periodically discharges the battery down to 12.2v ( theoretical 70% SoC governed by the load being applied ) and once the battery discharges down to 12.2v while under load, the alternator reverts to 14.7v and the BMS then monitors how much charge the cranking battery takes and how long it takes to get back to a fully charged state.

NOTE, this can take either one long drive or a number of short drives to achieve the necessary data required.

But there have been quite a few problems with this system, like where voltage have remained at 12.2v and other issues, that there is a software patch for the corrections.

Next time you are at a dealers for servicing, ask them to check that the upgrade has been carried out.

Hi Drivesafe,

Thank you for the response.
How long would you expect for the battery to take to get down to the 12.2v level under the Battery Management System control?
I presume around 2 weeks as this seems where mine sits. There are quite a few posts over the years which say to just charge the start battery every 2-4 weeks to keep it healthy.
My irritation is that a modern vehicle requires this closer attention. I had a D2 prior to the D4 and I suppose I am comparing the difference in behaviour. The D2 stayed charged for a lot longer.

Thank you for the tip about the software update. I will enquire.

Do you have any knowledge of the CCF setting for the Battery Management Sensor?
If it does revert to a standard charge profile like 13.7v and the battery is NOT discharged I will tolerate the resultant extra fuel used, negligible though I suspect it will be.

At the moment I connect the start battery to my van and let its solar keep everything charged, as you suggested in a post in 2018. This is working, but I have noticed that the Battery Management System will try to discharge the van batteries on occasion.

GIL

Originally Posted by drivesafe

Hi Milton, what size DC/DC unit do you have?

50A (Well that is what it is set to)