This topic is probably getting old . I've read through many threads about the dead/draining battery problems and watched a bunch of YouTube videos, but I feel like I'm stuck. To summarize, about a month ago, my battery was dead enough there wasn't enough power for the interior lights. O'Reilly's said the battery was bad so I got a replacement. A month later, my battery dead again. I jumped it and drove it and my battery tester says it's healthy. If I leave it overnight, it's holding a charge reasonably well. For example, it might drop from 2.8v to 2.6v. My guess is that the trouble comes when I don't drive for a number of days.

Here's what I've tried:

1. Disconnected the negative battery cable and connected my multimeter tool to the negative terminal and the detached cable.
2. The multimeter showed between 70 and 150 milliamps.
3. Tried unplugging a bunch of fuses under the hood and traced it to the famous Back Up ACC fuse. Pulling that dropped to basically 0 milliamps. Then the fun began...
4. I removed every fuse on the driver's and passenger's side, but nothing made a difference.
5. I unplugged the harness from what I believe is the bluetooth module (black box on the passenger's side with a blue or green connector). Still nothing...
6. Tried unplugging all of the harnesses near the BT module. no change.

At this point, I'm out of ideas.

 

Interesting. I'm in my first year of ownership with a 2006 RL, with 180k miles.

Recently, I needed major work in the timing area as the tensioner broke. So, all the timing belt/water pump area items were replaced. (Super frustrating, as the prior owner had done the work 20k miles prior -- but with shoddy parts).

Anyway, the shop surprised me by saying that they couldn't keep the battery charged. Every time they tried to test drive it they needed to jump it. This was super surprising to me, as I'd not had a single battery issue! Seemed to come completely out of the blue.

The shop replaced it with a new battery (only charged me $140, which made me wonder why it was so inexpensive, if factory-spec'd).

Anyway, fast forward 1 month:
2 days ago, the car was driving fine... After a brief stop and a restart, the SEL came on, there was a message about Emissions, the SH-AWD light and message came on, and my code-reader gave me 4 codes (P0172 was the first -- fuel running rich).
This seemed super weird to me. I'd been driving very casually and sensed no change at all in the car. A bit later I stopped, cleared the codes, restarted. Nothing. And then a few minutes later it all happened again, identically: SEL, EMISSIONS - SH-AWD - 4 codes (I kept my OBS scanner connected).

Crazy... What would the All-Wheel Drive system have to do with Emissions and Fuel/Air ratios?

The next day (yesterday), my wife was out driving my car and ended up stranded. She completely lost acceleration ability. The car would start, and rev up, and then stall out. Fortunately, she got to safety. We had the car towed home (Sat. afternoon -- no shops open).

So, today I went out to the car. I wanted to confirm the other 3 codes (I think they were successive P0170, 71, 72, 73 or similar).
And the car battery was completely dead! No lights, no door locks. I wondered why the AAA tow truck guy would have disconnected my battery.
Checked the battery connections: fully tight.
1 month new battery, and it's completely dead!

So, maybe the battery problem is at the root of the stalling, the emissions and SH-AWD codes.
We'll see...

 

So, yea... the codes are because of the battery and stop letting your wife drive a car with problems...

The question is, is the alternator working?
Even if the battery was being drained the alt should run the car after start.

Solving this would be:
1. fully charge the battery
2. have the alternator tested
3. have the battery tested
3a. just because its "factory spec" doesnt mean its a good battery.
4. IF you find the battery and the alternator is good proceed to 5
5. Use a meter to watch the amp draw in the car and pull fuses/relays until the draw stops.

Lastly its pretty well know that the bluetooh module can kill the battery.

https://www.google.com/search?q=acur...&bih=722&dpr=2

 

So, my shop confirmed: it was a charging problem. They replaced the old battery connects and also replaced the (dead) battery with a 2nd new one in a month. All codes and warnings went away.

So far so good for almost 48 hours. The car drove smoother and quieter than it ever has in my owning. Last week I was hearing some engine/exhaust growl, some kind of rattle, and the A/C fan was sounding super loud and high pitched. All odd. Anyway, ALL of these sounds were gone! It caused me to wonder how many various components are affected by a low power draw or charging system issues.

But today!
After a 20 mile round trip (including 2 freeway stints), I experienced what my wife experienced last weekend: all of a sudden, there was a loss of power, the RPMs jumped and fell, and the car started stalling (1/2 mile from my house). I restarted and was able to get to our home complex, while the stalling resumed. I pulled up on the larger driveway -- where a tow truck can access the car -- just in time. I heard a deep growling sound coming out of the exhaust. I got out and recorded 10 seconds of the sound. I checked under the hood. I tugged momentarily at the negative battery cable (which was snug) -- and the car immediately stopped.

So, the battery is out again.
The shop DID test the Alternator and said it tested good.
I see on my records that the Alternator was replaced by the prior owner in 2014 and 2018 -- 4 years and 54k miles. This has now been 5 years and 47k miles. So, maybe it's going out.
If the car loses power WHILE DRIVING -- that's the Alternator, right?

I WAS using Bluetooth at the time. But, I haven't had faulty bluetooth or problematic messages to indicate that the module is failing.
I HAVE had an obnoxiously loud "Connected" announced each time. If volume is above 10 it can tear my head off. That "started" a few months back; so something seems up with that. I'll check some more of those threads.

So, if the battery is dead, I can jump it and drive 4 miles to the shop. BUT, if the alternator is bad, I'll stall out on a major street. Looks like another AAA tow coming up.

 

So weird...
- The car retains power. Door locks, all dash lights, radio, A/C.
- The car starts up...
- Then within 2-10 seconds it dies.

On a phone call, my tech is saying that doesn't fit symptoms for a bad alternator.

Calling the Tow truck...

 

Is the battery flat at this point in time ? If yes (the battery that started the car just fine, has become flat by the end of a 20 mile drive), then yes the battery is not charging. It's been flattened by powering the electronics as you drove along.

This is weird - you would generally expect an alternator to last a very long time. Way way more than 4 years / 54K.

Yes, or at least the battery is not charging for some other reason (bad connection, bad earth etc.).

As per first question, did you confirm the battery really is flat at the end of the 20 mile drive when you made it to the driveway ?

Here's how I like to think about it.
If the alternator is working, then the car electrics run entirely from alternator power. The battery does nothing but start the engine.

If the alternator is not working, then the car electrics run entirely from the battery. After a while, the battery becomes flat, especially if you use high-drain circuits like the wipers and the high-beam headlights.

 

I agree.
If the battery is running flat, then it won't be able to start the car. The fact you started the car OK means the battery at least has some level of charge - I suppose it's possible it was right on the edge, and so it just barely started the car but didn't have enough left to do anything else - but I think this is pretty unlikely.

A battery capable of starting a car should be able to power everything else for way way longer than 2-10 seconds.