Member Since: 04 Jan 2023
Location: Essex
Posts: 526
Operation of the Aux battery
Is there a wiring diagram for the later models, I am particularly looking for info on the Aux battery and the Stop/Start system.A visitor from the dark side, my other vehicle is an MG5 EV
6th Jan 2024 10:57 pm
Carl and Petra
Member Since: 13 Feb 2015
Location: Hautes Pyrenees
Posts: 195
Why is that? Just wondering.
6th Jan 2024 11:03 pm
HairyFool
Member Since: 04 Jan 2023
Location: Essex
Posts: 526
The battery is both small and expensive for what it is. I need to replace it but want to understand how the system works before investigating upgrading it.A visitor from the dark side, my other vehicle is an MG5 EV
7th Jan 2024 12:49 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13657
Hi
Managed to find a 2016 wiring diagram but alas is in Italian , can’t seem to find one in English
Hopefully u may be able to translate it but can’t on my iPad
Member Since: 04 Jan 2023
Location: Essex
Posts: 526
It does help to some degree, I'm not surprised about translating text within a PDF but I will look at it on my PC.
However there are only a few references to "batteria ausilleria" so reduces the translations needed a bit. A visitor from the dark side, my other vehicle is an MG5 EV
7th Jan 2024 2:16 pm
Gary_P
Member Since: 03 May 2016
Location: Kent
Posts: 1523
HairyFool wrote:
The battery is both small and expensive for what it is. I need to replace it but want to understand how the system works before investigating upgrading it.
I've not had any issues with mine (other than the first one lasted just over 3 years from buying the car new) but wanted to check what prices you have seen for it , as I paid just over £40 for my replacement. OEM but not LR branded. By the way, my replacement has lasted over 5 years (that's jinxed it !).
cheersGary
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Discovery 4 HSE 2016MY
7th Jan 2024 2:22 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13657
HairyFool wrote:
It does help to some degree, I'm not surprised about translating text within a PDF but I will look at it on my PC.
However there are only a few references to "batteria ausilleria" so reduces the translations needed a bit.
Hi
Glad it helped in a small way , have spent a good while to no avail trying to get a translation that will work on my iPad , fingers crossed u have better luck with ur PC
Apologies if you’ve already done it but would it be worth popping down to Halfords to get it tested , as a side note buy my batteries from them seeing it’s a lot easier to then swap the batteries if there’s an issue
Bought my first battery online and failed after 3 x years , was a nightmare as no courier would accept it so that’s why I went to Halfords
Also think the main battery has a BMS module whereas the aux battery doesn’t, hopefully that’s correct
Plse let us know how u get on
7th Jan 2024 3:03 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13657
Also looked on the RRS that had the 3.0 stop start system, enclosed it here just in case it’s of a similar design
Starts at page 513 , goes into more detail ref the stop start system from page 538
Hope this is more useful to u , indeed just need to download it and will then make it bigger , found it easier to read using Microsoft 365
DUAL BATTERY SYSTEM - AUXILIARY BATTERY TDV8 4.4L DIESEL ALL MARKETS AND TDV6
3.0L DIESEL COLD CLIMATE VEHICLES
The dual battery system on vehicles with an auxiliary battery, allows both batteries to be connected in parallel, to
provide increased amperage to the starter motor for efficient starting in cold climates. The auxiliary battery assists
the primary battery in operating the starter motor to crank the engine at a sufficient speed for efficient starting. The
auxiliary battery is switched in parallel with the primary battery once the ambient temperature falls below a certain
threshold, or the state of charge of the primary battery falls below a predetermined charge level.
In addition, in the cold climate vehicles with TDV6 3.0L diesel engine with stop/start system, the auxiliary battery
supplies the sensitive loads when the ECO start is active. This is similar to the all markets vehicles with stop/start
system, where a secondary battery is fitted.
The power supply distribution box contains two banks of MOSFETs, which operate to introduce the auxiliary battery in
parallel with the primary battery, or to switch the auxiliary battery to supply the sensitive loads when an ECO start is
required. The power supply distribution box connects or isolates the batteries on receipt of LIN bus information from
the GWM.
When the engine is running, all electrical systems are powered from the primary battery and the generator. The GWM
and the power supply distribution box communicate via the LIN bus, and the power supply distribution box isolates
the auxiliary battery from the system.
The GWM monitors the state of charge of both the primary and auxiliary batteries to ensure that sufficient voltage is
available for the next ECO engine start. The GWM can apply charging to the auxiliary battery via the power supply
distribution box, if it is required. If the charging of auxiliary battery is necessary, the power supply distribution box
connects the auxiliary battery, and the generator starts to charge it
When the ambient temperature is below a predetermined level and the GWM receives a start signal via the high
speed CAN Powertrain bus from the CJB, the GWM communicates with the power supply distribution box via the LIN
bus to keep the primary battery connected, and also connect the auxiliary battery. The power for the starter motor is
supplied from both batteries. When the ECM receives the start signal, it energizes the starter relay in the EJB which
operates the starter motor solenoid to operate the starter motor.
When the ECO start is required (cold climate vehicles with TDV6 3.0L diesel engines with stop/start system), the
GWM sends a signal to the power supply distribution box via the LIN bus. The power supply distribution box isolates
the primary battery from sensitive loads, and the primary battery supplies the starter motor and power loads only, to
ensure the quick engine start. In same time the power supply distribution box connects, the auxiliary battery to
supply the sensitive loads, while the ECO start in progress.
7th Jan 2024 3:22 pm
HairyFool
Member Since: 04 Jan 2023
Location: Essex
Posts: 526
Unfortunately the D4 is completely different.
The Aux battery is similar to a motorcycle battery mounted in the front of the secondary battery box on the drivers side.
The battery runs a number of systems independently of the main battery when ever stop/start kicks in to reduce the drain on the main battery (which ones?), it is not directly involved with restarting the engine.
The BMS does monitor the condition of the Aux battery as if below charge or failing stop/start is inhibited ( I have had one person insist that the Aux battery actually restarts the engine, it only has a 100A fuse).
I have built a couple of rally cars with dual batteries. One off loaded almost everything from the starter battery with the engine stopped to allow longer wait times at controls with reliable starting. The other much simpler one just stuffed 24v into a 12v truck starter motor, tended to make it spin a bit faster A visitor from the dark side, my other vehicle is an MG5 EV
7th Jan 2024 10:57 pm
HairyFool
Member Since: 04 Jan 2023
Location: Essex
Posts: 526
1st off, translating a PDF of the type like the wiring diagram is not possible it would appear. Adobe class the PDF as be ing closed so cannot edit individual parts. Even they suggest using a file import tool such as MS Word to load and translate a text document, this is not going to work with a wiring diagram where text and graphics are so intermixed.
Did a little bit more digging on the back of GStuarts post and found this:
Component location 3 of 3 item 5 appears to be the same module as is the secondary battery box with our tiddler of an auxilliary battery. If right the module itself will support a larger 2nd battery giving longer run time with the SS system in Stop mode.
The bottom of that section (above "POWER MODES") is interesting in that it explains some reasons for the Auxiliary battery being used but I suspect the option to parallel the batteries is not enabled. I do wonder if the need to do so in the RRS was in part due to the location of the main battery, I don't think the long starter cables did it any favours.
Also, not entirely obvious but the PDSB box does have fuses in it.A visitor from the dark side, my other vehicle is an MG5 EV
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