Hey all, my 05 430 car battery will go dead after about a week of not driving the car. Is this a normal thing that some of you experience?

Because I only cruise the car on the weekends, so
the car sits the entire week without starting, but I mean, the battery shouldn’t rapidly drain in only 5 or 6 days that seems a bit extreme.

I’m not sure what’s going on, I thought maybe I had left the dome light on, but no, everything is turned off. Does anyone recommend where to look or another possible drain could be coming from?

BTW I have new battery that’s only 8 months old and it’s a AGM battery so it’s pretty beefy with lots of reserve power.

Thanks in advance guys.

 

Is it getting fully charged? It takes a long while to actually fully charge a car battery - many people underestimate that.

Next, put a meter on the battery w/the car idling and see the voltage. Make sure the alternator is working. Rev it a little (2000rpm is fine - does not need to be that high) and check that value, too.

Before suspecting a parasitic drain, also consider it could be a bad battery. A lot of people are experiencing premature battery failures the last few years - and especially w/AGM batteries. They are not at all what they used to be.

 

How old is your battery?

You can check for parasitic draw. Three methods of determining parasitic draw and which method is the best. Long video but worth the time.


I use a BateryMINDer maintainer on any battery that is going to sit for 14 days, per the maintainer recommendation. My experience is a battery can still start the engine even after 4 weeks, but I don't make a practice of leaving it off the maintainer for this length of time.

It's not good for a lead/acid battery to be deep discharged over and over.

 

No she should not be going flat after a few days if fully charged.
Mine currently only gets driven 1 or 2 days per week, but at least one of those is at least 30 miles so she gets charged fully.
If she sits for longer than a week without being used I plug in a battery maintainer.

Check the trunk light is going out when closed.
You can put your phone on video record in the trunk and close it to check.
Otherwise you will need to hook up an ammeter in series with the battery to see how much current she is drawing and start pulling fuses to see what stops the drain.
Don't forget that after hooking up the ammeter you need to wait at least 15 mins for the car to "settle down" into standby mode.

 

Search function will answer a lot of questions.
https://www.clublexus.com/forums/ls-...tery-life.html

 

And make sure all the doors are completely closed. If one is not closed completely the interior lights will drain the battery quickly - I know this from experience.

 

One other point. Your LS430 was not designed for AGM batteries. Therefore the battery charging profile is not right for the AGM and the system does not charge at a high enough amperage and in the proper rotation to properly recharge the battery. Putting AGM batteries in cars not designed for them is one of the leading causes of flat batteries, because they never get properly charged up.

https://www.interstatebatteries.com/...n-agm-battery#

 

I had the exact same issue. So this is what I came up with. 1. I think my smart key was too close to the car. 2. I just locked my car with the door controls and not the key fob because I think the alarm is what drains the battery. Ever since I did that, my problem went away.

 

These cars are not designed to fully charge an AGM battery. The AGM battery requires more current than the alternator provides to charge properly. My amateur guess is that you do not have a parasitic draw.

Since you have a relatively new AGM battery you probably don't want to change to a new traditional lead acid battery.The appropriate solution is to use a battery "tender" when the car sits for more than a few days at a time. If you get a quick disconnect with extension to match the battery tender, you can run the connector through the front grille. Then, you can connect/disconnect without opening the hood. Alternatively, the quick disconnect can be routed out the engine compartment towards the windshield and sit next to the passenger wiper.

Also, a charged jump box in the trunk is helpful.

 

Thank you all for your great advice.

It’s very odd because I had this same exact issue when I first bought the car late last year. The owner installed a brand new lead acid battery that was only 2 months old and I was having the same exact problems now as before. A slow battery drain that eventually completely killed that new battery which was also due to a bad alternator which I replaced, and I’m still having the same issues.

I was also thinking that the alarm could be causing a rapid drain, so I’ll try to disable the function for a few days to see if any improvements are made.


I’ll also head over to Autozone tomorrow sometime and have them check to see if my new alternator is going bad. The voltage on my volt reader is steady at 13.6-13.9 volts while the car is at idle. It was around 14-14.2 volts when I first started up the car then the voltage slowly dropped an after running for a few minutes.

I didn’t know about AGM batteries not being compatible with our cars. BTW the battery installed is only like 8 months old. I never had issues with it until recently. The car just sits a lot and is only driven on the weekends, sometimes I do forget to drive it, so it might sit another couple of extra days or so.

One thing I noticed right away with the new AGM battery is how it woke up the sound system and how much brighter the lights looked. It could be my imagination playing tricks on me, but I did notice this change instantly when I replaced it from the new lead acid battery that died so quickly and wouldn’t take a recharge anymore.

A battery maintainer is definitely something I will look into as I also believe this car just like my 460 don’t like to sit too long as the computer systems in them are constantly sucking power from the battery, especially the 460’s.

I’ll also have to try the phone in the trunk trick to see if the trunk light might be stuck on, didn’t think of that one lol.

 

Well I think I might have found my problem .

I noticed just now at night time that rear map lights are constantly on, but they are very very dim. Even when I locked the car the lights wouldn’t turn off. All the doors were completely shut as well.

The previous owner must have installed LED bulbs that are dual purpose where it was constantly drawing low power although the switch isn’t on. It always had this low glow which I realized is not normal.

So I removed them and we'll see if that was the cause of the drain, which I honestly think it is. It makes sense since it was a very slow drain.

 

I find this car to be tough on batteries.

The first two I had were Sears DieHard and they lasted 6 years almost to the week. Third through Seventh were the Costco Interstate batteries which barely lasted 6 months each THEY WERE CRAP. Faced with the end of the warranty I returned the last dead battery and bought the Sure Start battery from O'Reilly which has done well in my SC. Admittedly these cars don't see much weekly action but the Sure Start lasted 4+ years in my SC before it was replaced this year.

If the battery is fairly new I can leave the car for 3-4 weeks and it will start, but it's good to drive it for 30 min or so to completely recharge it after that.

So it could just be crap batteries. I find the cheaper ones these days honestly not worth the money.