Upgrading the stop start battery

[Bakes_RRSoffroad]

Has anyone had any luck with removing the small stop start battery and replacing it with a larger Deep cycle battery?
I am looking to do this upgrade to run a fridge and a caravan, I was wondering if this was possible with out any modification to the charging or battery isolation systems?
from what i have read this should just be an easy swap an the cars battery motioning system will allow the charge of both batteries ?

any help would be appreciated.

[Pedro_The_Swift]

Ok,, first off let me get my head around stop/start uses its own battery... after that the size of your replacement is dependent on LOTS of issues,,
My first thought would be to put a battery ( or two) in the Van,,
is the fridge in the car or van?
the car batt would run an "in car" fridge overnight,,

so many questions.... [smilebigeye]

[Bakes_RRSoffroad]

The end goal is to run a fridge and other small accessories off the second battery, the stop start system uses it own battery which is located in the rear RH panel in the boot.
From what i have read the vehicle already has a system in place that disconnects the (AUX) battery when it detects that the voltage drops below a certain point, this inhibits the stop start function From working and doesn't allow the AUX battery to drain the main battery, I want to know if i can just change the small AUX battery out to an optima deep cycle battery and keep the stop start system and also use it to run my accessories, I believe that RRS have a 70AH battery installed in the same spot on cold climate models ? if what i think is correct the car will already have a second battery charge system in place ?

cheers

[Gregz]

Ok,, first off let me get my head around stop/start uses its own battery...

The stop/start battery is not actually used for starting - it is used for maintaining power to sensitive systems while the main battery does the starting.

I think Bakes may be onto something... I will have to re-read the ws manual.
Others, without the stop/start battery, have put a separate battery on the other side of the luggage compartment.

Or, Bakes, how about you try it out for us and let us know how it goes [bigsmile1][bigwhistle]

[WizudOfOz]

Interestingly when I was researching putting my aux battery in my 2016 SDV6 HSE, I couldn't find the stop-start battery behind the RHS cargo panel.

The little tray which I've seen reported to hold that battery had some other kit there:
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So, if there is a stop-start battery I don't know where it is!

I did put a 120AH aux battery behind the LHS panel. There's a couple of posts detailing how I did it.

Craig

[Barryp]

Very interesting. Great photo .
Regards
Barry

[Gregz]

So, if there is a stop-start battery I don't know where it is!



I might actually lash out some $ on Topix and get some updated WSM information. The only WSM I have at the moment is from late 2013 early 2014, (which appears to be all you can get on ebay) and it looks like there were some significant electrical differences into 2015 and 2016.

[DiscoMick]

Does the vehicle's stop-start system actually do the same functions as a dual battery system? I had always assumed they would be quite different. Wouldn't running a fridge off the stop-start battery system still flatten the starting battery?

[Nessie]

I've just last week had a battery problem, and this may shed some light on the start/stop functionality.
I've had my 14 and a half Rangie for a few months now, and the Start/Stop has never been active. I just presumed the previous owner had the dealer disable it.
Well, last week we loaded the back seat up with a weeks worth of holiday crap, hitched up the trusty Jayco Swan Outback and loaded up the Border Collies in their harnesses in the back.
Hit the Start button, one crank, and then nothing. Nada. Zip. Zero.
Not happy Jan.
Anyway, NRMA got me started as they didn't have the appropriate battery in stock, and we got to Moruya without turning the engine off.
Another call to NRMA to get them to come out and fit a new battery, and they turn up with the wrong battery, and can't get the right one for a number of days. Even less happy...
Sourced a correct battery from the local Bursons outlet at an eye watering price, and the local NRMA guy fitted it for me for free.
So, back on the road and finally happy.
Two days later on the next decent run lo and behold the Start/Stop turns itself back on! Caught me out at a set of lights in the pouring rain!
So, the up-shoot is that the "system" monitoring the main battery (which is used for the starting circuit) disables the Start/Stop if the battery capacity falls below a certain level.
My old battery was down to a 300A capacity rather than the 800A needed.
There is no auxilliary battery that we could find, so that's a furphy.
Lesson here is not to rely on Road Service to save your butt if your battery fails, and if your Start/Stop ceases to function get your battery checked. It's a bitch to get to under all the guff in the boot.

[Gregz]

Hi Nessie,
what is your engine?
Mine has the stop/start battery as in this photo.
152247

[Nessie]

Hi Greg, mine is a 2014(1/2) HSE SDV6. The last model before the AdBlu came in.
It’s the same as the photo at the top of the thread.

[Fly501]

bringing back an old thread here, but curious if you (the OP) ever found your answer?

I have been searching to find info on the BMS system for the 2016 LR4/D4 which has lead me to searching forums over seas including this one. I'm in the central US and have the same questions/goals.

On the LR4 the factory aux battery is located under the hood (i wish it was in the boot) and unfortunately the size of the space only allows for a minor size upgrade, but none the less would allow for more capacity. Assuming one goes lifepo4 there may be even more there to work with. Lifepo4's don't like heat but with a proper BMS on the battery you can limit the extremes and whats is a 25-50% reduction in the life of a $400-500 battery that has a 2,000 - 2,500 cycle life. Rarely does one get cycled all the way down anyways.

I have several thoughts on how to approach the power needs I have but finding out how the factory dual battery BMS works has been nearly impossible. Found some info on a german forum about how the BMS works for non start stop equipped units from the 2012-2015 era, but nothing on the late 2015-2016 models (pre capacitor VQMS approach). But my thinking is the same as yours. There is already a DC-DC built in, as well as a battery isolator. The alternator on the LR4/D4 is either 150a or 180a and variable voltage. (thats my logic for thinking there is already a DC-DC) and that the isolator protects the main (start) battery giving you a factory dual battery set up.

[Barryp]

L494's from 2016 on have a capacitor instead of the stop start battery.
My understanding is the stop start battery or the capacitor version is only there to stop a voltage drop to the cars computer system during stop start operation.
Its only a tiny battery in the battery version, its nothing like a starter battery.
Regards
Barry

[drivesafe]

Hi Fly501 and welcome to the forum.

:welcome:


The STOP/START battery is there to do nothing more than maintain the vehicles electronics and has nothing to do with actually starting the vehicle.


This is purely guesswork, but I would be surprised if there is anything more than a relay separating the cranking battery from the STOP/START battery.


As to the DC/DC device, well I suppose you could call the alternator the ultimate DC/DC device but I again would be surprised to find an actual DC/DC device, because the vehicle’s own BMS could easily monitor both batteries and if either, or both needed charging, the BMS would simply ramp up the output voltage of the alternator to meet the needs of either battery.


This is virtually the same thing a DC/DC device does.


If you find there is a diode, or more likely, fets used to separate the batteries, you may be able to use a lithium battery as a replacement for the STOP/START battery.


BUT, if the batteries are separated by nothing more than a relay, you may create some problems for the vehicle’s BMS.

[Fly501]

L494's from 2016 on have a capacitor instead of the stop start battery.
My understanding is the stop start battery or the capacitor version is only there to stop a voltage drop to the cars computer system during stop start operation.
Its only a tiny battery in the battery version, its nothing like a starter battery.
Regards
Barry


After reviewing your comment and the thread I think there is a disconnect between what the OP asked, his make/model, and what I saw in Gregz's posts with his factory aux battery. Your understanding of the capacitor/VQMS is also what i understand to be the new method of addressing the vehicles power needs between start/stop process cycles. Thanks for the reply however.

[Fly501]

Thanks for the welcome.

Yes the factory aux battery is there to only run systems while the engine is off and doesn't provide power to the starter motor, agreed.

But the comments and thought process you are considering as to how the system works is what I cannot find any info on. Probably because they appear to have maybe only used this system on 2-3 models for 1-2 years before going the other route? (not sure how to verify what models/years this was on but might be nice to know for a later summary post)

I just got done reading another thread that has several of your posts and comments and based on the above you surely seem to know, or understand the approach to managing the electrical systems a bit better than I do and I appreciate your time and consideration.

I'll be more than glad to take photos of things, but part of my struggle is in knowing what to look for and where. I know enough to be dangerous, not enough to be smart, and I am rarely lucky!!

Between the cranking battery and the Aux battery (from what I can see) are the factory power wires bring the power over the other side of the engine bay and terminating into the "Dynamic Start Stop Module"part number ej3214f70-ab https://www.ebay.com/p/8026257802?iid=352560467133. To which I can find zero info on in terms of what it does, other than the description via the part name itself. So maybe it can simply be removed and the car move on its merry way? I just discovered this MAY also called the "Gateway Module", however I seem to get conflicting info on that assessment. In the GAP tool, the Gateway module does include info on the dual battery voltages, and a host of other electrical references to which live values can be read/logged. Everything from quiescent factors to SOC, to battery 1/2 voltage, etc. But i cannot find a "Dynamic Start Stop Module" in the tool. NTSB shows a bulletin for a known issue with some of them staying on and draining batteries, to which the service bulletin shows a test function on the JLR software but not sure if that parrallels GAP tool or not. https://static.nhtsa.gov/odi/tsbs/2015/SB-10057688-4680.pdf

In terms of the DC-DC comment I am not sure I understand how the system would ramp up and apply voltage to each battery individually? Yes the alternator would generate more current to handle the charge, but how would it manage that independently? I guess its possible the part referenced above is just one fancy relay/isolator and not a DC-DC? But I they are just wired in parallel at least we know that. I got part of my thinking as to the DC-DC from this article Battery, BMS & charging – Discovery 3 / 4 – DiscoveryParts (https://www.discovery-parts.de/en/batterieprobleme-beim-discovery/) but its possible they are just referring to the alternator as a fancy DC-DC?

(forgive me if links aren't posting correctly, hopefully copy and paste works)

I wouldn't know where to begin to look for a diode vs a fets? Could you elaborate on where or what I am looking for?

Until I can figure out how to determine that, for the sake of discussion, let's assume for a moment there isn't one. I assume a seperate dc-dc would fix the issue of the differing batteries, and since the battery is so small a 10a could work, or a 25a, but either way I would be running two if I am attempting to put more power in the rear and not sure it that would be an issue either.

In looking into this, I constantly feel I have more questions than answers. It's 2am here so I am going to bed, but will be sure to follow up as I am able and truly appreciate you time and consideration. (even if you don't have the answers)

Cheers

[drivesafe]

Hi Fly501 and as I posted, my comments were purely guesswork.

While I have worked on quite a few different makes and models of vehicle with the STOP/START function, all of them are the single battery type.

I have seen a couple of the Land Rover two battery types but have never had the opportunity worked on one.

This is just a suggestion. There is a device called a BM2 Bluetooth Battery Monitor.

See the link below for more info.

If you get two of these devices, and they will continue be handy once you set up what ever dual battery system you end up with.

You can fit one to each battery and they should give you all the info you need to determine how your two battery system works, including see if there is a DC/DC setup in your vehicle.


https://www.aulro.com/afvb/the-verandah/261576-bm2-bluetooth-battery-voltage-monitors.html

[Fly501]

Drivesafe, purely guess work or not, good logic none the less.

Can you clarify what you mean by "You can fit one to each battery and they should give you all the info you need to determine how your two battery system works, including see if there is a DC/DC setup in your vehicle"
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Or how one would determine the DC/DC exists? The LR's gateway module provides for live value monitoring of the batteries, alternator, I believe even current flow. Possible I have the ability to already see this same info (however I do like these and like the wire free use, alarms, etc so will still look into adding them)

Here is a log file from a driveway load test I did just to see how and what info was available. A basic sequence was Start truck let idle for around 30 seconds, start adding load (via seat heaters, defrost systems, radio,) for around 30 seconds, bring RPM's up and hold for around 30 seconds, let off accelerator around 10 seconds, and at 100 seconds I start shutting things off, stop log 10 seconds later.

If there is another measure I am looking for or manual test that could be done will be glad to try.

Here is a log file from a driveway load test I did just to see how and what info was available. A basic sequence was Start truck let idle for around 30 seconds, start adding load (via seat heaters, defrost systems, radio,) for around 30 seconds, bring RPM's up and hold for around 30 seconds, let off accelerator around 10 seconds, and at 100 seconds I start shutting things off, stop log 10 seconds later.

[Fly501]

Found this in the service manual. It provides quite a bit of info and perspective on how the system works.

Looks like there are mosfets used.

https://lookaside.fbsbx.com/file/D4%20Battery%20Management%20and%20charging%20syste m.pdf'token=AWxGSg6WOxZyiQ23gF1zC4rRumLdHI0mD-uAQ-Qlfvx4XYGYf6vHrQ2_yTvd1vFyIR8XAVDJsK_KS6EJxNoScUQC JK-GSvuWqplHXAbNaPaN3xN1TOaG3sULJMnuBXdYPBxCGXusnd7XE qL7ZJoe1SL74pKIQHEXsoFQUEMG06SEwzpEYdw2EF-0XpXdGy8LNYPnVInpAkCZsA_zmq_41YMj8Tju0g0UEF8tZLOSh ZTrWA

[drivesafe]

Found this in the service manual. It provides quite a bit of info and perspective on how the system works.

Looks like there are mosfets used.

https://lookaside.fbsbx.com/file/D4%20Battery%20Management%20and%20charging%20syste m.pdf'token=AWxGSg6WOxZyiQ23gF1zC4rRumLdHI0mD-uAQ-Qlfvx4XYGYf6vHrQ2_yTvd1vFyIR8XAVDJsK_KS6EJxNoScUQC JK-GSvuWqplHXAbNaPaN3xN1TOaG3sULJMnuBXdYPBxCGXusnd7XE qL7ZJoe1SL74pKIQHEXsoFQUEMG06SEwzpEYdw2EF-0XpXdGy8LNYPnVInpAkCZsA_zmq_41YMj8Tju0g0UEF8tZLOSh ZTrWA
Thanks Fly501, that is a great bit of info.

I have not read it all yet, but while fets ( mosfets ) are used, it does not make it clear as to the whether they are used in a Buck ( DC/DC ) type application.

[Bails]

Interesting thread, I have the SDV8 2016 and have been thinking a Lithium battery to replace the stop start would be good. My rationale would be to have a live 12 v outlet in the rear to run a fridge. From reading it seems that a fridge can run for 3 to 4 days on a 48 Amp Hour Lithium. Seems there are some thin lithium's around for $500 that may fit the space , and since cranking amps are not required this would serve me well.