On the C5 X7, and on many other PSA vehicles a 'Battery Charge Status Unit' (BCSU) is fitted to the negative battery lead.
For those that want to know what it does: -simplified
The role and function of the BCSU is to calculate the battery charge status and transmit this information to the BSI (Built-in Systems Interface) to fine-tune the activation of the energy economy mode. The battery charge status is calculated from measured physical parameters (voltage, current) and calculated parameters (battery internal temperature).
The battery charge status unit has a role permitting optimisation of the management of the electrical energy.
The battery state of charge unit contains the following functions:
- Autodiagnostics reporting any faults detected on the sensors and/or internal electronics of the battery charge status unit
- Storing of the minimum current consumed on the 12V network when the vehicle is on standby
- Detection of crossing of an ancillaries battery charge threshold every 10 % with triggering of the built-in systems interface BSI
- Making the measured physical quantities available (Voltage, current and temperature of the ancillaries battery)
- Detection of disconnection of the ancillaries battery
You would then get double the time you next drive the car up to 30 minutes max. before economy mode engaged again next time - in theory.
However, with the advent of the dedicated BCSU, this unit undertakes the calculations and management of the battery and tells the BSI directly when to cut off the consumable device power. Unfortunately it is far too sensitive, as aptly noted by many who have new batteries (myself included) who cannot get more than a couple of minutes out of the radio.
I have also become aware of the specific issues affecting C5 X7 Tourer owners, which have the electronically opening and closing tailgate. Many find they can't get more than a single opening before it dies a death - which kind of defeats the purpose really.
So to try and provide a solution to the problem there is a parameter within the BSI (dependent on BSI software version) that can transfer control back to the BSI.
I make no assurances and no guarantees - so please don't come running back if your battery goes flat But if you know your battery is good and want some extra time this should work. The BSI should continue to shut down power to devices when the battery is weakened - but I guess feedback from members who decide to try this will confirm. I have the saloon, so no tailgate to worry about - but already my power hungry NG4 head unit is happily playing a DVD with no shut down after the configuration change
The change will require a VCI with Diagbox to telecode the new parameter. Please follow the common sense approach when changing any parameters to your cars BSI, like making sure you have a fully charged laptop and that it is connected to the mains wherever possible (to prevent the laptop going into power saving mode during a configuration change of the ECU, that could brick it).
Important!: Please do not apply this fix to cars with the Stop & Start system fitted. This is because the Battery Charge Status Unit plays an integral role in determining the battery charge state and is utilised in determining the various operational stopping and starting strategies employed with this system!
- Hook up Diagbox, switch on ignition and allow it to identify the vehicle.
- Select Fault Finding and complete the Global Test.
- Allow the test to complete fully, then scroll right to the top and select BSI.
- Press the green tick bottom right of screen to confirm selection.
- Follow any instructions to switch the ignition off / on as required.
- From the next menu, slect Repair.
- Next select Configuration.
- Then choose Manual Configuration.
- Next, select Vehicle Configuration.
- Now choose Driver Information.
- Scroll down the list / next page until you see the option for 'Battery Charge Estimate Function'.
- Highlight this selection with the mouse, then press the green tick, bottom right of screen.
- Now press the green tick again and you will see 3 options.
- Select the 'Present, Done by the Built in Systems Interface option. It should be the last option.
- You will be returned to the previous screen, where at the bottom right, is a Cog Wheel, next to the green tick button.
- Press the Cog Wheel button only - do not press the green tick button!
- This will apply the configurations and the entry should now have changed.
- If you have the 'Present, Done by the Built in Systems Interface' option showing you have done it correctly.
- Now press the arrow at the bottom left of the screen, to keep backing out of the menus, all the way to the front screen, then close Diagbox and unplug the VCI.
So please let us know if this helps with your electronic tailgate issues - but be mindful to check your battery condition regularly.
|Driver Information Screen||Highlighted Option Shows BCSU by Default|
|Select Last Option on list||Cog Wheel to Apply Configuration|
|Press Cog Wheel to Apply Change||Configuration Confirmed|
To revert to the default parameter, follow the same steps and re-select the 'Present, Done by the Battery Charge Status Unit' option.