Range Rover Sport Parastic draw... or is it?

Hi all,

I'm currently wrestling with what appears to be a parasitic drain on my 2005 Range Rover Sport (L320), but I'm hitting a dead end with it and was hoping someone could help.

Symptoms:

• Battery almost fully discharges after ~48 hours

Steps taken so far:

1. Recorded & Measured DC amp drain over ~24 hours. Amps rest at about 0.012 amps i.e. 12 milliamps... battery was still discharging.
2. Unbolted alternator.... battery stopped discharging! Must be the alternator right? (Or a diode in the alternator?)
3. Got alternator tested at a local electrician and they said it was good.
4. Bought a new alternator anyway! Bolted it in... battery still discharged.

Could someone give me a new way to approach this? Is there anything I'm missing or overlooking?

Any help would be appreciated,

Zeki

If a car battery is discharging in 48 hours with only 12mA been drawn, then the battery is seriously knackered!.

Have you tried replacing the battery?, it possibly could have an internal current leak? (a LOT more than 12mA) that's discharging the battery.

Hi Nigel,

Sorry I forgot to mention that I have indeed replaced the battery. Although I feared that the battery being discharged to such a low voltage repeatedly may have compromised it, I had it load tested today and I was told it was good.

Any other ideas?

Thanks for all of your help. I really appreciate it.

Zeki

zekik64 said:

Hi Nigel,

Sorry I forgot to mention that I have indeed replaced the battery. Although I feared that the battery being discharged to such a low voltage repeatedly may have compromised it, I had it load tested today and I was told it was good.

Any other ideas?

Thanks for all of your help. I really appreciate it.

Zeki

Click to expand...

Find where it's all going - 12mA is NOTHING for a car battery - if it's going flat there's got to a LOT more current going somewhere, and perhaps only intermittently?.

12mA from a (good condition) 60AH battery would take 5,000 hours to completely drain it.
Even 500 hours should only be 10% down, which should not compromise the capacity at all.

Flattening a vehicle starter type battery does cause serious degradation & typically they can only stand it around half a dozen times before being wrecked. The capacity drops to near zero, which could explain the battery

Other possible causes of battery failure / finding it flat are:
Old age - they do degrade, typically anything from three to five years regular use before the capacity is too low for them to function normally.

Higher starting current than the battery is rated for, or much longer starting times, due to a failing starter motor or engine problems.

A faulty alternator - insufficient output to fully recharge the battery after each start, or over-voltage causing overcharging.

As others have said, 12 mA isn't bad at all, and won't flatten a good battery in 48 hours. It will barely make a dent. The headlights will take around 1000 times as much current, so if the car will start after leaving the headlights on for 5 minutes with the engine stopped, then 12 mA won't kill it in 48 hours. It could be the alternator is taking 12 mA, but it doesn't matter where the current is going if it's that little.

Have you measure the drain without disconnecting the battery? I suggest that you run the engine for a bit, and then stop it, and then measure the current. Obviously meters that can accurately measure 12 mA can't usually be left in series with a car battery when the alternator or starter are running. One way to get over that is to connect an isolator in series with the battery, and turn the isolator on, run the engine for a couple or minutes and then stop it. When the engine is stopped, and everything has shut down, connect the ammeter across the isolator and open the isolator.

The reason for this is that one of the faults that can cause a car to flatten its battery is if the systems fail to shut down. I don't know about the L320 specifically, but many cars have modules that are only connected to the rest of the car via power and CANbus. There are signals on the CANbus that are there to let modules agree when it is time to shut down. If the the modules don't shut down, then several module would be taking 0.1 - 1 A each, and then 48 hours is around the time that you will get.

If there is a problem that stops the car from shutting down, resetting all the modules by disconnecting the battery might make the fault go away, but it could come back when the engine is run.

Getting modules to sleep and wake is quite an involved subject, called "Network Management". One type of Network Management is Autosar, and that is described here:- https://www.autosar.org/fileadmin/u...ssic/4-2/AUTOSAR_SWS_CANNetworkManagement.pdf in 98 pages of unreadability. There are other methods used as well to decide when modules should stay awake or shut down, and there can be more than one system running on a single CANbus.

Another thing is that if you have any sort of battery management sensor, often connected to the negative of the battery, sometimes as the ground lead, you should not connect anything else to the negative of the battery. Any accessory should be connected to a supply and to the body. If current flows to the battery negative that doesn't flow through the battery management sensor, it will confuse the system and it might not charge the battery correctly.

I had a 2007 Hyundai Veracruz with exactly the same issues.
Just like yourself, I replaced the battery and alternator, without positive results.

Then I went into a very time consuming method of removing one by one the fuses, to determine exactly which circuit was drawing the parasitic current.
It turns out that it was something in the “infotainment area”. Unfortunately for me, the infotainment circuitry consists of several submodules and it wasn’t feasible to determine the actual culprit. Additionally these modules are a pain to reach and replace, requiring significant disassembly.

I sold the vehicle.

Zeki,
Not sure if you fixed the draw but I had a similar parasitic drain. Drove me round the twist trying to find it too, turned out to be the upper boot lid release switch (above numberplate). They get corrosion in them, easy to strip down and clean or replace. Took 2 days to flatten full battery.