I just replaced the battery on my 05 RL last month (I bought the car 2 months ago) because after 1 day of not driving it, the battery would be so weak that the car wouldn't start. I know the previous owner already replaced the battery once a couple of years ago, so I figured it was just time to replace it again.

After the battery replacement I have driven the car every day for the last month, everything was fine.

However, I was out of town for 5 days, this morning I go to start the car and it is completely dead. The dome light doesn't even come on.

I know my alternator is good and I know the battery is good, what could the problem be?

I have heard of some power drain issues on 05 RL's, but what is the cause? What parts are the likely culprits?

Thanks in advance.

 

The XM Unit. on the drive side of the trunk behind the carpet. I believe it is the bottom connector on the unit back there. i do not use XM so disonnecting it does not bother me.

Also ive seen a few issues of amplifiers blowing a cap and keeps drawing power so remove the amplifier and test Pins to make sure that the amp is not drawing any power

 

You could simply have a bad battery. A way to determine if the car is the culprit is to use an Ammeter in series with the 12V terminal to see if there is a current draw. I have had a battery die within a month on Legend #1, and O'Reilly's replaced it for free determining the battery was defective.

 

agree w/ oo7spy. simply a bad battery.

 

I killed a new battery by leaving my cellphone "on" and in the car over the weekend. Since it was in the garage and unlocked, the bluetooth kept searching for a connection and drained the battery.

 

The Bluetooth shouldn't be active unless the car is "on" right?

I vote bad battery too, get it tested for free.

 

I know the BT will stay on for a while after the car is off, but I did not know it was indefinite. Still, a BT transponder should not have enough current draw to drain a 12V battery with the capability of pushing 700+ amps. I can leave my BT mouse linked for months before the 2-1.5V batteries will die. I think something else was left on and the BT was blamed.

 

Remember the issue with using the Trunk unlock button on the door. Lots of people complained about flying out on biz trip and coming back to dead battery.

 

Back when my old battery was about to go out, I had gotten home and was still talking on the phone. When I shut the car off, the car said "To conserve the vehicle battery, the call is being transferred to the bluetooth phone."

So the RL has some kind of electronics that prevent a BT phone from running down the car battery entirely.