Electrical mods

[TB]

Has anybody got insight into how to approach electrical system enhancements on a DS?

#1 for me is an Anderson plug or similar for my portable compressor, so I don't have to keep taking off the battery cover and using the alligator clips. I guess that the simplest thing would be to fit a plug directly off the battery in the engine compartment. It might be nicer to have one down in the boot instead though if that's possible.

I know nothing about the electrical system in this car so please point me to info if you know where I can get enlightened. I did poke around in the back and found this behind the panel on the passenger side:

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I tried checking for 12V on that chunky red wire but couldn't get my multimeter probe in the back of the plug to touch metal, and didn't want to pull the plug in case it messes something up. It would be convenient if that wire was a nice high current tap straight back to the battery – I could possibly tee off that for a socket. It wouldn't work if these wires went dead without the ignition on though. Unless...

Another possibility might be to have a luggable second battery pack which could charge while the car was on and power my pump or other things when I'm stopped.

Looking for advice and inspiration, folks. Any thoughts?

[Mamil]

If you just want to be able to run a compressor I wouldn't bother running directly from the battery, or messing with the junction box in the boot, just tap into the towing electrics circuit. This is already pre-wired into the DS (something the dealer doesn't want you to know so they can charge you a fortune to wire it for towing) and will either terminate at the tow socket if you have a tow bar fitted, or in a connector in the boot if you don't.

This provides both a 15A ignition switched feed and a 15A permanently live feed. Not as high current capacity as an Anderson plug which is usually 30A or 50A, but plenty for a 12v compressor if that's all you want to run off it.

The wiring diagram below will help you identify the right wires, but usual warning applies - don't mess with this stuff unless you know what you're doing, get an auto electrician to do it for you instead. The permanently live wire is just that - a permanently live connection direct to the battery!


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[TB]

Mamil, that's awesome! Where'd you get that diagram? The forum software has scaled it down so it's hard to read the detail.

I do have thoughts about fridges and second batteries rolling around but for the time being a 15A direct from battery sounds pretty handy for the compressor.

[Mamil]

Mamil, that's awesome! Where'd you get that diagram? The forum software has scaled it down so it's hard to read the detail.

If you register with the LR online service portal "Topix" Browser not supported (https://topix.landrover.jlrext.com/topix/vehicle/lookupForm) as an Independent Operator you can see the build spec of your car, access accessory fitting instructions and handbooks for free, and see what outstanding service items there are on your car. Then if you go one step further and pay for a subscription you can access the dealer service bulletins, workshop manual, and wiring diagrams, which is where I got that one from. I've attached it in PDF format so it's easier to read...

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Edit: Don't know why the forum is saying "Browser not supported" but that is actually a working link to Topix

[Mamil]

Correction!

I just checked my compressor and it draws 45 Amps, but it is a pretty big one at 160 L/min. So, check your compressor and if it's over 15A then I take it back - you would need to run a new feed from the battery to an Anderson plug in the rear, which incidentally would also come in handy for the fridge you are considering. I knew there must be a reason I attach my compressor direct to the battery rather than using the trailer socket [bigsad]

[TB]

Thanks again. I tried subscribing to topix for a day yesterday morning but the payment process was messed up.

Yeah I thought 15A might be a bit low for a compressor. I've got the Dr Air AC495 150lpm... and I just found out its normal working current is a bit shy of 45A with a peak close to 60 when there's no back-pressure!

So I would need a 60A connection to the back of my car, or a second battery back there with an isolator and such. Time to ask an actual sparky I think.

[drivesafe]

Hi TB, and while I have no intentions at this time to produce a dual battery kit for the Discovery Sport, if you didn’t mind a drive down to the Gold Coast at some time, I would be happy to take a look at what you already have in your DS and see if I could give you some assistance.


I would also be getting a look at a DS and could see if a simple setup was viable.

[TB]

Hi TB, and while I have no intentions at this time to produce a dual battery kit for the Discovery Sport, if you didn’t mind a drive down to the Gold Coast at some time, I would be happy to take a look at what you already have in your DS and see if I could give you some assistance.


I would also be getting a look at a DS and could see if a simple setup was viable.

That's a date – thanks! :thumbsup:

Will reach out via pm in the next couple of weeks.

[DiscoMick]

If all you want is a compressor Anderson plug connection couldn't you just connect it to your battery and tie it to the battery clamp so it can't move?

[TB]

If all you want is a compressor Anderson plug connection couldn't you just connect it to your battery and tie it to the battery clamp so it can't move?

Yep. That's plan A.

[SohansWorld]

Hi (may be a dumb question) but I have a compressor that has a Cig Lighter socket at the end ... and I use it all the time to fill up my tires ... is this bad?

[drivesafe]

Hi SW do you know the current draw of your compressor?

[trout1105]

Hi (may be a dumb question) but I have a compressor that has a Cig Lighter socket at the end ... and I use it all the time to fill up my tires ... is this bad?

The majority of compressors that have the cigarette lighter plugs on them are fused inside the plug and don't draw that much ampage anyway which is a good thing, Unfortunately they take forever to reinflate a set of tyres and most of them die an early death.

[SohansWorld]

Thanks ... good to know ... I have so far used it to check and top up my car tires so I didn't know any different ... I might invest in a better one before going out to the beach ...

[drivesafe]

Hi folks and anyone considering wiring a high current drawing compressor in any new Land Rover, not just in a DS or D5, and this info relates to any high current requirements, connect the positive lead of the device or DBS to the craning battery’s positive ( + ) terminal.

DO NOT connect anything to the NEGATIVE ( - ) terminal of the cranking battery.

On most new vehicles, not just Land Rovers, connecting any medium to high current loads to the negative ( - ) terminal of the cranking battery can cause problems seemingly unrelated to the battery or charging system.

So connect your device’s negative returns to a good earth point, such as the same point where the cranking battery’s negative cable is bolted to the vehicle’s body/chassis.

[trout1105]

Hi folks and anyone considering wiring a high current drawing compressor in any new Land Rover, not just in a DS or D5, and this info relates to any high current requirements, connect the positive lead of the device or DBS to the craning battery’s positive ( + ) terminal.

DO NOT connect anything to the NEGATIVE ( - ) terminal of the cranking battery.

On most new vehicles, not just Land Rovers, connecting any medium to high current loads to the negative ( - ) terminal of the cranking battery can cause problems seemingly unrelated to the battery or charging system.

So connect your device’s negative returns to a good earth point, such as the same point where the cranking battery’s negative cable is bolted to the vehicle’s body/chassis.

Agreed.
Doing it this way also has the added bonus of only having to run a single (+) wire to wherever you want to mount the Anderson plug [thumbsupbig]

[Mamil]

Hi folks and anyone considering wiring a high current drawing compressor in any new Land Rover, not just in a DS or D5, and this info relates to any high current requirements, connect the positive lead of the device or DBS to the craning battery’s positive ( + ) terminal.

DO NOT connect anything to the NEGATIVE ( - ) terminal of the cranking battery.

On most new vehicles, not just Land Rovers, connecting any medium to high current loads to the negative ( - ) terminal of the cranking battery can cause problems seemingly unrelated to the battery or charging system.

So connect your device’s negative returns to a good earth point, such as the same point where the cranking battery’s negative cable is bolted to the vehicle’s body/chassis.

Hi Drivesafe, I'm about to tackle this job over the Easter weekend, so am glad I found your post. I will be running a 16mm2 feed with a 40A fuse from the car battery through an Anderson plug at the rear of the car, to a 30A DC-DC charger in my caravan supplying a fridge and charging the house battery while driving. So, could I ask you to expand on why it's not good to connect the negative direct to the battery negative terminal? As the negative chassis point is itself directly connected to the negative battery post by a short (about 10cm) cable, I'm wondering what the difference is? Appreciate any advice you can give for my intended setup. Thanks.

[BobD]

Hi Drivesafe, I'm about to tackle this job over the Easter weekend, so am glad I found your post. I will be running a 16mm2 feed with a 40A fuse from the car battery through an Anderson plug at the rear of the car, to a 30A DC-DC charger in my caravan supplying a fridge and charging the house battery while driving. So, could I ask you to expand on why it's not good to connect the negative direct to the battery negative terminal? As the negative chassis point is itself directly connected to the negative battery post by a short (about 10cm) cable, I'm wondering what the difference is? Appreciate any advice you can give for my intended setup. Thanks.

Good question. I was wondering the same thing. After careful inspection of the DS battery I decided that there was only one thing connected to the negative terminal and that is the short length of thick cable connected to the body earth. I therefor connected the clamps on my portable ARB dual compressor straight to the battery terminal as it was easier to get to than the body earth point. No problems so far, touch wood.

[DiscoMick]

I'm probably wrong, but can it cause a gassing problem?

[drivesafe]

OK folks, I think there needs to be some research done on just what sort of alternator charging goes on in the DS.

I have not had the time to even look at a DS, let alone test their voltage operation, and it sounds like they may not have a “smart” alternator operation, because there does not seem to be any monitoring of the cranking battery.

So if someone has the means, can you monitor the voltage of your DS while it is in use.

[Mamil]

OK folks, I think there needs to be some research done on just what sort of alternator charging goes on in the DS.

I have not had the time to even look at a DS, let alone test their voltage operation, and it sounds like they may not have a “smart” alternator operation, because there does not seem to be any monitoring of the cranking battery.

So if someone has the means, can you monitor the voltage of your DS while it is in use.

Oh there's definitely battery monitoring going on, and from the excerpt from the DS service manual below, I'd say it's a "smart" alternator with variable voltage charging and regenerative braking.



BATTERY MONITORING SYSTEM (BMS)
The BMS (Battery Monitoring System) control module is located on the battery negative terminal, and connected to the
BCM/GWM assembly via a LIN bus connection. The BMS module contains software maps that provide a mathematical model of
battery conditions, and constantly receives information from the BCM/GWM assembly regarding the vehicle state and electrical
loading.
The BMS control module monitors various battery parameters, which are directly measured and predictive values:
Battery current and voltage are the result of direct measurement;
while State of Charge (SoC), State of Function (SoF) and electrolyte temperature are predicted values.
These signals are used by both the charging system and the stop/start system to ensure the vehicle functions are optimized.
The measurement is autonomous and happens in all states to enable an accurate condition of the battery to be assessed at all
times. Software based values are calculated and used as a backup in the event of a system fault condition.
The BMS control module also has a hardwired connection to the battery positive terminal. This connection is used to avoid any
potential voltage drop in the circuit which results incorrect information received by the BMS control module. If this connection
becomes open, the BCM/GWM assembly detects a communication loss with the BMS control module. Then the BCM/GWM
assembly default to a fail-safe fixed charging voltage of 14 Volts, stores a related DTC, and sends a message to the
Instrument Cluster (IC) via the MS Medium Speed (MS) Controller Area Network (CAN) comfort systems bus to illuminate the
charge warning indicator.

OPERATION
The charging system consists of a generator and regulator assembly and the BCM/GWM assembly. The generator and
regulator assembly generates electrical power for the vehicle electrical system and maintains the battery in a charged state.
The rate of charge for the battery is controlled by the BCM/GWM assembly.
The charging voltage range is 12.3V to 14.8V (at the battery).
A smart regenerative charging system increases the alternator output when the vehicle brakes or decelerates. This converts
the kinetic energy of the vehicle into electric energy without having to use additional fuel.
The smart regenerative feature is allowed to operate within certain environmental constraints to ensure the feature delivers
the greatest benefit possible whilst maintaining system integrity.
The ‘free’ electric energy is captured by charging the battery above the target level. This energy can be used by the electrical
systems at a later stage. This could be when the engine is switched off during a stop-phase, but can also be when the
generator is operating in a less efficient mode.


In fact the Service manual also contains the following warning:-

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Is this the reason you suggest not connecting auxiliary power take-off directly to the negative terminal of the battery, because it could damage the sensitive BMS unit? Though I would have thought there would be a difference between a "slave" power supply which is putting electrical power into the battery, and an auxiliary take-off which is taking it out, but happy to be corrected by those with more experience than me...

[Burndtjamb]

OK folks, I think there needs to be some research done on just what sort of alternator charging goes on in the DS.

I have not had the time to even look at a DS, let alone test their voltage operation, and it sounds like they may not have a “smart” alternator operation, because there does not seem to be any monitoring of the cranking battery.

So if someone has the means, can you monitor the voltage of your DS while it is in use.

Hi all, I'm new around here, although been driving a disco sport for almost 2yrs. I'm looking at doing some electrical mods in the near future so this thread grabbed my attention.

While doing some short drives around town today I managed to track the battery voltage a bit:



12.7V battery only
Dropped to low 11's during cranking
The alternator seemed to initially put through 14.5V, dropping to 14.1V over about a minute
After a few minutes, it was fairly stable at 13.8V with the A/C on and 14.0V with A/C off.


I'm fairly new to vehicle electrics, but that looks like the behaviour of a smart charger to me. Hope that's the sort of info that's useful, drive safe.

MY16 2.2L diesel btw.

[drivesafe]

Hi Malim, and where on earth did you get that from.

Calling the alternator a generator sounds like the backward mouthings of Land Rover.

Next, the use of the expression Regenerative Braking is a misnomer, because there is no such thing as Regenerative Braking in a conventional vehicle.

Regenerative Braking is only found in electric hybrids or all electric vehicles, where they have electric motors directly driving the wheels.

The only part of that “info” they got right was that it is the vehicle’s kinetic energy that is used to power the alternator.

And note, the alternator voltage level has absolutely nothing to do with the use of the Brake Peddle.

The alternator’s Voltage raises every time you lift your foot of the ACCELERATOR Peddle.

Any one can test for this by driving their vehicle up a hill and the coast down the other side.

While going up the hill ( provided the cranking battery is near fully charge ) the voltage will be low, and then when you lift your foot off the accelerator peddle, the voltage rises, and it remains high while you coast down the other side of the hill.

[drivesafe]

Hi all, I'm new around here, although been driving a disco sport for almost 2yrs. I'm looking at doing some electrical mods in the near future so this thread grabbed my attention.

While doing some short drives around town today I managed to track the battery voltage a bit:



12.7V battery only
Dropped to low 11's during cranking
The alternator seemed to initially put through 14.5V, dropping to 14.1V over about a minute
After a few minutes, it was fairly stable at 13.8V with the A/C on and 14.0V with A/C off.


I'm fairly new to vehicle electrics, but that looks like the behaviour of a smart charger to me. Hope that's the sort of info that's useful, drive safe.

MY16 2.2L diesel btw.

Hi and thanks Burndtjamp, that is exactly what is needed.

The info Malim posted about not touching the negative terminal is correct and commonplace on most new vehicles, not just Land Rovers.

The voltage levels are determined by the SoC of the cranking battery.

Lower the voltage of the cranking battery, which is exactly how my isolators work, when using the auxiliary battery while the motor is off, and once the motor is running again, because the SoC of the cranking battery has been lowered, the alternator voltage will run higher for longer, to recharge the cranking battery in the shortest drive time.

This also means the auxiliary battery is teated to a high charge cycle as well.

There is more to is but thats the basics.

[Mamil]

Hi Malim, and where on earth did you get that from.



As I said in the original post, it's straight from the Discovery Sport workshop manual, I'm just relaying what LandRover say about their system.
However, you still haven't answered my question, ie: why do you say not to attach the negative of an auxiliary feed to the battery negative post, and attach it to the chassis earth connection instead? Thanks.

[drivesafe]

As I said in the original post, it's straight from the Discovery Sport workshop manual...Thanks Mamil
For the life of me, I have no idea who they get to write these documents.

Using the brake, and decelerating, has nothing to do with the voltage levels.

As I posted, and anyone from Land Rover should be aware that the voltage is controlled by the accelerator peddle.

Simple measure the battery voltage as you roll down a hill, which by the way, is where you will get the longest charge periods.

While coasting down a hill, just touch the accelerator peddle and the voltage drops.

The only time using the accelerator peddle does not effect the voltage is when the cranking battery is low and the BMS overrides the info from the accelerator peddle position.

[bezzita]

sorry off topic: I can't create a post for some reason.

how do I get this electrical diagrams and part numbers? I tried register in TopiX but can't get these diagram unless you paid subscription.

Thinking to do retrofit memory seat for my Discovery Sport, anybody have a clue how to do this?

TIA