About a year ago I left an interior light on overnight and the battery was flat the next morning. I jumped it without issue, took my 45 min trip and no issues after - started right up every time just as it did prior.

A few weeks ago I was hanging out in the back with a female companion with the radio on (engine not running) and after maybe 15-30min the battery was dead. Again, I jumped it, took my 45 min drive back home and have had no issues since.

Tonight I was washing my car, and if you’ve done it before with the key in your pocket you know it’s always unlocking when you touch the door handle and locking by itself a little after. Also the little courtesy lamps are turning on when you get close. I’ve washed it many times with the key in pocket. So when I finished I got in to pull it back into the garage and the battery was essentially dead. Struggled turning the lamps on and moving the steering wheel and then couldn’t start. Again, I’ve done this many times and never had an issue starting it up.

I’ll try jumping it in the morning tomorrow before I take off for my long drive into town.

My question is, what’s the normal amount of time you can run the radio/accessories without the battery dying? In my old BMW I was able to turn the radio on/off without having the ignition turned to any setting - really wish we had that option...

Im probably due for a new battery after all this nonsense and see Costco/Interstate offers an AGM battery for almost double the price of the standard battery. Debating whether it’s worth it...

 

Arizona heat destroys auto batteries in quick order. If you get 2 or even 2.5 years you're doing well. Now the temps there are hitting 100 it's prime time for battery failure. Don't spend money on an expensive battery rather find the best battery/warranty value you can find. I lived there for 19 years

 

My advice is to test the battery. 15-30 min indicates it's likely not in good shape.

It's funny too how BMW has gone mainstream (made the turn signal, wiper stalk, cruise control, all go mainstream, unlike the way they used to be)--you like the feature of not having needing actual accessory position to run the stereo. I do too. My wife's is a GM--it too does not need to have the key in acc to listen to the radio, although I am not sure what the timeout is. If a door is opened, it turns off. imho the LS430 is a 2000 car with a traditional key, and a "smart" key function was added later. So it would seem the door handles behave like a smart key system, but the ignition and acc/ON functions like a 1970 car. My story that I stick to, is hey Porsche made the owner turn a key too to start well into the 2010's, so my LS430 is like a Porsche, design wise. Great engineers think alike. yeah, right.

There's something called RC, in addition to CCA, when rating the batteries. My BMW is specifically designed to provide heat after the engine has been shut off, for maybe 60+ minutes (I'd have to read the manual and a) don't know where it is b) I'm a guy). I have only used that feature 2X since 2007, and once was to test how long it would continue to work and to provide heat to the cabin with the engine off. Well, it was 30 min before I got a battery warning. I do recall as well the temp was in the low 20F's. And, the battery at the time was 5 y.o. So maybe if the battery were new? It would do 90-140+ min. but I would think the heat would diminish as well, so not sure if there's an algorithm to say turn it off due to coolant temp being too low to provide heat. Again, if you look at modern cars (I'm talking 2008+), many cars that have a lot of demand, have two batteries.

The LS430 has a 24F battery. A 1998 Maxima with cold weather has a 24F battery (without cold weather package it got a 35). The Maxima has zero components other than a stereo, that can be used in the accessory position. So imho the engineers designed the LS430 as Nissan did the Maxima of 1998, not a lot of high demand, no need for a super sized battery. Which suits me fine because the flip side is it's $85 at Costco, not $140.

 

Batteries don't like to be drained down to a depleted state. The fact that you ran the battery down with the interior light, live in Arizona's heat, and have had some additional issues, leads me to believe it's time for replacement. As mentioned above, batteries within the southern states with extreme heat generally last up to 3 years max. No need for AGM for our cars. Walmart offers a very good warranty for their best battery with free replacement. I've dealt with their batteries in all my cars with no issues. For the cost to replace an item that could leave you stranded in the middle of nowhere....why hesitate? Good luck.

 

Living in Arizona for 52 years, I just replace my Costco battery ever other year, before they fail. Don't waste my time testing, just replace the battery for a few bucks and you're good to go without experiencing battery problems or failure.

 

Even with a garage it was always early summer, when the temps hit the 100 to 105 range, when they would die.

 

Get a new battery from either Walmart or Costco. Both come with at least 36 month full replacement warranty.

Be aware that paying extra for typical long multi year extended prorated battery warranty is pretty much worthless. Also be aware that for wet cell lead acid core battery, there are just 2-3 battery makers left in the US. There are dozens of brands being sold at many price points but all of them are essentially the same battery with a different colored case and label and of course different marketing and hype.

What actually matters is the full no cost replacement warranty. Get the least expensive battery that gives you a 36-42 month minimum no cost replacement.

 

Solid advice as always from Jabberwock.
btw Just replaced a failing one which was in the 2006 LS when I bought the car, with a Duracell Automotive Battery - Group Size 24F which came with a warranty of 36 months Free Replacement for $102.69 from Sam's Club (owned and operated by WalMart). At the same time, for my truck, I bought a Duracell Automotive Battery - Group Size 65 from Sam's to replace my failed Duracell Automotive Battery - Group Size 65 which had a 36 months Free Replacement warranty when I bought it. But, since I put in the truck 5 years ago in 2015, and the battery lasted 2 years past the 36 month free replacement, it cost $105.35. Battery installation is always FREE both at Sam's and at WalMart. But, since Sam's and WalMart automotive centers are closed due to the Wuhan China Covid-19 virus, it was cash and carry. The truck battery failed last month and the car battery was failing for the past couple of weeks. Was trying to hold out until either Sam's or WalMart automotive centers reopened. When found out WalMart corporate had not determined an reopening date, bought from Sam's as its store is closer, and besides previous Duracell battery from Sam's did last 5 years. However, WalMart's EverStart Maxx is a few bucks cheaper and has a better warranty of 5 years which is 3 years free replacement plus an additional 2 years pro rata. And, if you stop being a Sam's Club member, your battery warranty is voided. But, no membership required to keep you Walmart warranty for 5 years. Walmart also has quite cheaper batteries with 1 or 2 year warranties. And Walmart installation is always FREE. So, Walmart may be a quite a better deal than Sam's. And, if auto centers were open, would have gone to WalMart instead of Sam's.

East Penn is the manufacturer of Duracell automotive batteries. East Penn also manufactures Intimidator, Deka, and AUX batteries. East Penn makes all types of flooded, AGM (Absorbed Glass Mat), and Gel technologies lead-acid battery products.
Most EverStart batteries were made by Exide with a few made by Delphi which was sold to Johnson Controls. Read in one place that Exide also makes Marathon and NAPA. Then read NAPA is made by East Penn. Read Johnson Controls stopped making Interstate which is now made by Exide. Optima and Duralast were Johnson Controls battery brands and it also made Motorcraft. But, Johnson Controls Power Solutions sold off its automotive battery business to Brookfield Business Partners who rebranding it as Clarios. Now Clarios produces more than one third of the low voltage batteries in the entire automotive industry.
Over 40 different brands of batteries are made by East Penn, Exide, and Clarios.

 

2 years ago I sat waiting for a train (Eurotunnel Shuttle) for 4 hours with the radio on and I had to borrow a jump pack to get her started.
To be fair the battery was at least 4 years old at the time and had run flat twice during the Covid lockdowns before I hooked her up to a battery maintainer.
The battery is a 70Ah so in theory should last for ages when just using the radio, but you have to have the ignition in the ACC position which energises all kinds of stuff so I won't risk that again.
I also bought my own jump pack just in case. It lives in the spare wheel well and I take it out over Xmas to recharge it.
Mine must be due a new battery soon as it is at least 6 years old now.