I bought my 2004 RR in Dec last year, had a few mornings where the car wouldn't start without jumping during the cold period. It has been parked since Monday, just went to move it and the battery is dead, not quite enough juice to turn over.
Not sure how old the current battery is, is it just a case of replacing it and any recommendations for replacements?

Hey Tom,
I had a similar situation with a 5 yr old battery. I flattened it twice with no idea how. So once I got it jump started from the RAC man, I then went for a 30 mile drive and later charged mine overnight with a ctek conditioner/trickle charger.

Rather than spending on a new battery straight away, I decided I would look for an electrical drain on the battery, and found a 3amp drain which is only present if I close the diagnostic port cover. If i open it, the drain goes down to 0.9amp. This is still higher than it should be, but at least my battery seems to be lasting a few days without use now. Had i spent the money on a new battery it would have just drained down again in a couple of days with the 3amp drain and I would have been in the same situation. Once a battery drains a couple of times to completely flat it is often the end of the battery.

ECP is a good place to get a new battery from if you use their discount code of sales75 or sale75 something like that. It brings the price right down.

Mark

Wow 3 amp is a serious drain. Even 900mA is a lot. I had problems when I had a 250mA drain and only by getting it below 100mA has the situation improved. RR History
1988 2.4td Classic 1999 to 2020
1992 3.9efi Westminster Classic 2004-2005
2005MY L322 3.0TD6 Vogue 2016 to current

I agree, although many people say that less than 1amp is acceptable, but they say this with a slight hesitation. When I say people I mean the 2 RAC guys, Land Rover main dealer (although body shop) and also a friend who has run his own motor engineers for 60 years. I agree ideally it should be down to 0.1ma-0.4ma but it doesn't seem possible with all the tech on the car. Land Rover themselves told me that the L322 is renowned for this, and even many owners of 405s are complaining of flat batteries after a few days.

Before finding the cover for the diagnostic port was causing a 2 amp drain, one thing I did when testing, was leave the car for an hour and check - the drain remained at 3amps regardless.

When I found the issue with the diagnostic port, I didn't bother waiting to see how much the drain reduced from 0.9a after an hour or so as I had many other things i needed to get on with. But your reply is a timely reminder that I need to do more and see what the drain is after an hour, and see if I can find the root cause of the 2amp drain from the diagnostic port. I was hoping my post which is asking "if anyone else had seen the drain from the diagnostic port, or had any ideas why it might be the case" would provide a hint or two for me to chase down, but alas no responses yet.

Mark