Low Battery Warning

Tim, that's a pretty solid idea. I've been eyeing the CTEK options including the Smartpass unit which does a pulsed version of exactly what you're describing and also instant boost for cranking if needed. In both cases we'd need to bear in mind that the smart alternator leaves the starter partially empty even after the longest drives, so that capacity would be lost from the lithium sooner or later.

I need to run a test and see what kind of defensive options the vehicle takes if the starter battery gets meaningfully depleted. Maybe it stops powering up the infotainment system. Maybe that's fine for camping.

So far I haven't attempted any serious trips with the Defender, and using a Dometic PLB40 to power my fridge and lights has been fine along with a Noco jump starter to hopefully get me out of an actual flat battery scenario. I could hope for something far better though.

It's worth keeping track of the YouTube comments and PowerfulUK's responses.

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Originally Posted by drivesafe

Thanks One_Iota, that is a great video.


Hi Folks and this is just a suggestion for a theoretical fix for the high current draw occurring in these new Defenders.

I have already supplied a number of my isolators for use in some new Defenders but I have not created a kit, just yet.

Using my isolators and an AGM auxiliary battery dramatically reduces the problem BUT does not fix it.

I have also seen quite a lot about the problems being caused by the static discharge that occurs in the new Defenders and had feedback from a couple of customers who have had battery problems when the new Defender is not driven every day or so.

This shows that opening the doors is only part of the problem and just sitting unused for around a week can lead to a flat battery.

To be fair, how much the vehicle was used prior to the week of not being used is just as important.

After carrying out tests with a lithium auxiliary battery in my Tiguan, I am pretty confident I could near fix that battery draw and extend the cranking battery lifespan to near indefinite.

Again, this is a theoretical fix and would need testing, but.

You could fit say a 100Ah Lithium battery ( it will fit ) and because of the SMART alternator operation in the new Defender, you will need to have a DC/DC device charging the lithium battery while driving.


Nothing new so far.


The difference is once the motor is off, and the DC/DC device is off, connect the lithium battery back to the cranking battery.

You can not just use a switch or relay for this job as you will still need to protect the lithium battery against over discharging and causing the lithium battery’s BMS to shut down the battery as you would then need to manually energies the lithium battery’s BMS or the DC/DC device will not charge it once the motor is running again.

So you would need a Low Voltage Cut-Out device and this would also need to disconnect the two batteries the instant the ignition is turned on ( for a number of reasons ).

This setup would mean the lithium battery was carrying all the static discharge current when ever the motor was off, and could do so for many weeks, if not for a month or so.

It would also guaranty that the cranking battery would be maintained in a fully charged state at all times while the motor was off.

This would occur because the cranking battery has a rested voltage of 12.7 - 12.8v but a lithium battery has a rested voltage of 13.2v minimum, over 80% of its discharge cycle.

So the lithium battery would supply all the power for the static discharge currents while at the same time, continuously trickle charging the AGM cranking battery.

NOTE based on all the testing I have already carried out, this trickle charge current would only be 100 to 200 milliamps.


Anyway, this is just a suggested fix.

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Interesting idea. I already a 200Ah Lithium installed as my auxilliary battery with DC/DC charging and a heap of other stuff that I won't go into. I have recently set up a 200A relay and twin 25mm2 cables to parallel up the Aux to the Main battery. I set this up for 2 reasons: 1. To keep some load off the main battery when operatting the winch; 2. To operate as a boost for starting should the Main battery be drained down while camping. I'll give some thought to controlling to operate as you suggest. This may require a bit more electronics, or even a microcontroller to manage the various scenarios, e.g. when winching, I want the Main and Aux to stay connected with the engine running, whereas when not winching, as you say I want to disconnect the 'link' relay so that the Main Battery BMS doens't get it's knickers in a knot, reconnect the DC/DC for normal charging of the Aux, etc. Sounds like some more electronics design and code-cutting coming up :).

I've had the low battery warning come up a few times in the morning and most days the engine will kick over no problem, so I tended to ignore the warning. However...after winching a few times on the trails during the day and opening doors, charging various batteries overnight, and of course leaving the barn door open and car unlocked, I found myself in the predicament where neither my fully charged projecta 1200A jump starter, nor a donor battery in a patrol via jumper leads would turn over the Diesel engine. BE WARNED... these engines need 650 cranking amps in a dead flat situation. When the RACQ guy arrived (within the hour, mind you) he hooked up a lithium jump starter that brought the engine back to life immediately. It was a Projecta 1500A, 700amp clamping power. Don't believe the engine size ratings on jump starters, they won't work every time for newer diesel engines. Look for a unit that has minimum 650 amps at the clamps. They are pricey but definitely worth it.

Hi VillaDazzlar, and I’ll bet you did not carry out the correct method for just starting, when you could not start from the Patrol.

If the Projector 1500A could start your motor then there is no reason why the Patrol could not start your motor, unless you did not do the jump start properly.

Have a look at the link below, as this will explain the correct and SAFE way to carry out a just start on any vehicle, from any other vehicle, regardless of the two types of vehicles.

Incorrect jump starting is a very common practice.

https://www.aulro.com/afvb/the-verandah/246755-line-auto-electrical-info-4.html

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Originally Posted by drivesafe

Hi VillaDazzlar, and I’ll bet you did not carry out the correct method for just starting, when you could not start from the Patrol.

If the Projector 1500A could start your motor then there is no reason why the Patrol could not start your motor, unless you did not do the jump start properly.

Have a look at the link below, as this will explain the correct and SAFE way to carry out a just start on any vehicle, from any other vehicle, regardless of the two types of vehicles.

Incorrect jump starting is a very common practice.

https://www.aulro.com/afvb/the-verandah/246755-line-auto-electrical-info-4.html

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Hi, thanks for sending this link. This is what we did with the donor vehicle after exhausting the 1200A lithium jump starter:
1. Donor engine running
2. Red on dead, positive terminal in engine bay
3. Red on donor, positive battery terminal
4. Black on donor, negative battery terminal
5. Black on dead, clamped to engine, searched for a good spot
6. Revved Donor for 3 minutes
7. Switched on ignition in dead vehicle, ecu fires up.
8. Push start button on dead - click, click, nothing
9. Switch off ignition
10. Go back to step 6 and try again

After 3 attempts the owner of the donor vehicle no longer wanted to participate in the exercise.
Where did we go wrong? Should we have waited longer at step 6? I read on another post that there is almost 10 amps being drawn by the defender once the ignition is on.

When the RACQ guy connected his multimeter he reported 6.2V. After starting the vehicle from his 1500A unit he then measured 80+ amps flowing into the battery and concluded that my battery was in good condition.

Anyway, I have upgraded the dedicated lithium starter as an independent backup. I would prefer a smaller unit though - if I could rely on it working every time. Hopefully Land Rover push an update to the software with some type of low draw 'camping mode' which would also help.

Again, there should have been no reason for the Patrol to be unable to start Defender.

You either had a poor connection or the idle time needed to be longer.

Even if the Patrol was 20+ years old, with a small alternator, it still should have been able to jump start your vehicle.

AS stated, it does not matter how small the donor vehicle is or how large the disabled vehicle is, you can always use any vehicle to jump start any other vehicle.

My money is on the jump leads.

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Originally Posted by shack

My money is on the jump leads.

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Yes but not the size of the leads, just a poor connection.

I once had to jump start a tractor that had gotten bogged in a muddy field and they had flattened the battery because the tractor kept stalling.

It was at a relos place and I arrived the next day.

The field had dried out some what but the tractor was about 10 or 15 metres from a service road.

I had a S model Valiant at the time, with a 45 amp alternator.

I ran two 4m auto cables ( 2.5mm2 x 2 ) from the Valiant's cranking battery to the tractors battery and left the Valiant idling for about 30 minutes while we went off and had lunch.

They reckon it wouldn't work but the motor fired up at the first attempt.

Jump starting is not getting the donor vehicle to start the disabled motor.

The intention is to get enough of a float charge in the disabled vehicle's battery to allow it to start its own motor, with the assistance of the donor vehicle.

Even if the disabled vehicle's battery has dropped a cell, you can still put enough of a surface charge in a stuffed battery to jump start any motor.

I did a test last night, left the doors on the defender open, UHF on, and ran the stereo for a bout 3 hours in the shed. Left the doors open,UHF on all night and absolutely no issues starting this morning at zero degrees