Member Since: 02 Dec 2007
Location: nottingham
Posts: 35
2012 D4 Unexpected flat battery
D4 HSE parked happily on Thursday after use, not used Friday, wife went to car on Saturday and could not unlock it! Mechanical key seemed very stiff and did not want to break, so called LR Assist and they came a few hours later. Meantime a bit of WD40 got the passenger door open, and meter on battery showed barely 6V. A couple of hours or so on 4 amp charge (disconnected from car) and voltage crept up very very slowly until after a couple of hours with over 10 volts the battery could be connected and the other doors opened. When the LR Assist guy arrived still not enough volts to even try starting, but with his jump leads the car did spring into life with alternator then properly doing its stuff. Extensive tests with fancy toys convinced us there was nothing wrong with the battery but there was no explanation for the discharge - on shutdown the car was drawing a lot less than 100mA. Might have reset whatever problem by disconnecting battery and before he left the LR Assist guy updated some software modules which shouted about compatiility, but we were at a loss to understand why the battery had been flattened. Started OK this morning, any suggestions from the experience of others?
26th Oct 2014 11:16 pm
Pedros
Member Since: 25 Jun 2011
Location: Cumbria
Posts: 454
Not really. I suppose it's getting to that time of year when we're using more electrical gubbins to keep warm, keep the screens clear and so on. Perhaps if you do short journeys that could be an issue? Another point is that if you have your lights on automatic, when you're starting the car they come on, as do the brake lights as you of course have to have the brake pedal depressed. All that pull on the battery even before turning the starter motor!
They have a hard life do Disco batteries. Another thing of note these days is that you often get no warning of a battery failing. Time was, the starter would start to turn a bit slower and you'd be aware. But now, one minute it starts fine, you come out of the shop with your pancakes and the battery is in the same state as they are, perhaps without the maple syrup.
28th Oct 2014 9:33 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
That battery has had quite a hammering. It will need a long time on a conditioning charge, at least overnight but probably longer.
25mA or less would be an acceptable drain on a D4.Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 02 Dec 2007
Location: nottingham
Posts: 35
Thanks for the replies, clearly not a problem of usage, the car had done several hundred miles in daylight in preceding days. Car is only two years old so on past experience of discos (this is my third), I would not expect battery failure at this stage and indeed the car has started quite happily each day since the events of the weekend. The only reasonable explanation seems to be something not going to sleep properly as the car shut down resulting on a serious overnight drain taking the battery volts to a level I have never before seen. Let's hope we don't get a recurrence.
28th Oct 2014 10:25 pm
crews control
Member Since: 18 Mar 2007
Location: Dorset
Posts: 5011
My original battery started doing similar when it was just over 2 years old. If I left the car standing for more than 2 days, I wouldn't be able to start it. No current drain detected and passed all tests. We couldn't find out what it was and it took the dealer almost 6 months to give in and declare the battery knackered! No problems since.
These AGM batteries look like they can fail in weird ways. Either that, or my dodgy dealer was waiting until it was out of warranty! (he then wanted more than £300 to swap it - which he didn't get)
29th Oct 2014 6:41 am
cecilh
Member Since: 17 Jul 2012
Location: Johannesburg
Posts: 13
I don't suppose this has anything to do with the "intelligent" charging system? This does some funny things and allows the battery voltage to drop to 12.1 v on occasions, when the engine is running! Also for long periods of time when on thrips the voltage sits at around 12.2v and only gets above 13v when coasting in gear (re-generative charging). So when its on a long trip I sometimes wonder if its getting enough of a charge. Throw in a bit of a drain overnight and maybe next day problems start? Just think aloud.
29th Oct 2014 2:01 pm
petet
Member Since: 02 Dec 2007
Location: nottingham
Posts: 35
reassuring this doesn't seem to be a common problem, or we might have seen a few more replies. But got to be something more than a a poor state of charge for the battery to get dragged down to 6V in one day lack of use. Continuing OK so far this week!
29th Oct 2014 4:51 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Agree - that is a very poor voltage so either the battery has failed or something dragged it down. Given that the battery has apparently recovered the money is on the later.
Did you put the battery on a long conditioning charge?Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 02 Dec 2007
Location: nottingham
Posts: 35
Not yet! Been rather an eventful week with a lot going on, so the more surprising that the battery has stood up as well as it has - was planning to give it a nice steady charge to ensure happiness, but not yet had opportunity. Starting has been very brisk, with no time spent cranking, suggesting battery is still kicking out the amps as it was when the LR Assist guy checked it out. Suggests that the battery is also holding whatever charge it has gained, so as you say, money is on something having dragged it down - hopefully software upgrades will have alleviated the likelihood of recurrence. Definitely don't like the idea of the disco sitting there smiling without even a glimmer of life in its lights, and the only way in is mechanical lock on the passenger door - at least that works now.
29th Oct 2014 5:24 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Cranking is not a good indicator on the D3/D4 for battery state of charge.
As it happens mine is on its pre-winter conditioning charge right now.
Land Rover - Turning Drivers into Mechanics Since 1948
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