Battery Problem

[J H N]

I have a 2001 LS430 with 81,000 miles. When I don't drive it for 5-6 days, the battery will be discharged. The battery is 3 years old and was checked out today. The load test was good and I was told it must be an electrical drainage problem. I tested the charging and it was good. What is the most common cause of an electrical drainage problem?

JN

[VBdenny]

John, I would still suspect the battery. Usually when they test, the test is for voltage. What you need is a LOAD test on the battery to determine the juice it has with a load. Here is an easy way to check. Charge the battery and disconnect. Reconnect in a few days and see how it cranks, My guess is that it will not turn the engine. If it cranks like 900 and starts, then you have a current draw. From my experiences.

Denny

[pj8708]

Hi John and welcome.

Denny am I correct in saying that if the battery is ok, sometimes people find a loose negative strap where it bolts to the body?

Paul

[landar]

Welcome, John.

Your battery could be 'good' and still not meet your cars needs. All batteries are rated in Ampere-Hours, that is, the number of amps it can supply for a certain number of hours. So, for instance, if you had a 100 amp-hr battery, it could supply 100 amp for one hour or one amp for 100 hours before it was considered 'drained'(about 10.5v).

Your battery may be within the manufactures acceptable limits, as it was designed, for supplying a load, yet be degraded from when new and now falling short of the needs of your car. I would probably be looking for a new, high quality battery with as large a capacity as possible for your needs.

Now, you did ask what was the most common cause of drainage and that would be a light being left on. Usually interior.

[VBdenny]

Can't speak for the LS430 cars but I remember how much juice my LS400 needed to start. For whatever reason, these V-8 engines need a lot of power. Disconnect, let it sit for several days, reconnect and see if it starts.

I have hardly ever seen a loose ground on a car, not very common I think. Usually a corroded terminal connection.

[J H N]

The man at Sears Auto told me to disconnect the battery (after it had been recharged) for 5 days and then reconnect . If it starts, the battery is not the problem. I have 4 more days to go. I will let you know my results. Thanks for the help.

JN

[J H N]

Sears told me to disconnect the battery for 5 days and connect it and try to crank the car. The car started with out problems. I did an amp test on the battery. I used an amp meter to connect one probe to the disconnected neg. cable and the other probe to the neg. terminal on the battery. After about one min., the amp meter read 450ma -500ma. Does any one know what the current drain should be on a 2001 LS430 ? Is this too much?

[landar]

A continual 450-500 ma is way too much. However, you need to wait much longer than one minute. Leave it setup that way for 1 hour, and take a reading, then overnight and check in the morning. I do not know exact values but would guess the current should be less than 30 ma when all of the electronics is asleep.

Of course, make sure all the doors are closed and lights are off.

I could make a check on my 02' if you would like a comparison.

[J H N]

You were right. I left my Amp meter connected to the neg. pole of the battery and the neg. cable for 30 min. The reading decreased from 450-500mA to 30mA. Thank you for your expert advice.

J Nolen

[landar]

You are welcome, John. It sure seems like your car is behaving well and that your battery is pretty good as well. However, I would say that your battery, while still decent, is beginning to go downhill and can no longer hold up to the 30ma draw for 5-6 days. And it may be aggravated by the cold of winter. Not at all unheard of at 3 yrs old.

Probably time to look for a new, high capacity battery.

[J H N]

What kind and brand of battery do you recommend?

JN

[landar]

When it comes to batteries, I always try to get the best value for the buck so I stay away from parts stores like AZ, Advanced, etc. They have some good batteries, just overpriced, IMO. I also steer clear of Sears for the same reasons, unless there is a good sale going on.

I do not have a specific brand to recommend because there are many good brands. I try to find the biggest battery(size and CCA) that will fit my battery compartment with the proper post polarity position. I have had the best value experience at Sams Club.

[landar]

John, been thinking...before you go and buy a new battery, run another test. Simply leave your car sitting for 5 days with the battery connected. Maybe it will start ok? Maybe the first time was because a light was left on?

If you know for sure that the battery will be dead after 5 days, go ahead and find a new battery but if there is any doubt, just try the 5 day test again.

[VBdenny]

I will suggest a battery but only if you plan to keep the car for awhile. Optima Redtop. My 9 year old Redtop just started my Nissan truck after it sat for almost 3 months. Pricey but they last a long time and have a lot of juice.

[J H N]

I charged my battery on Thrusday and will not try to start it until Tuesday . That will be 5 days. I will let you know.

[J H N]

I left the battery in the car for 5 days and did not use it. After 5 days, The car started with out any trouble. The battery is good. I guess that a light was left on and that drained the battery. Thanks for all of the expert advice. As Paul Harvey used to say "Now you know the rest of the story" about batteries.

JN

[landar]

Yeah, something must have been left on and you may never know. It has happened to me too. I just make sure the battery is fully recharged and keep an eye on it. Believe it or not, there could still be a problem with the battery being intermittent internally and shorting out but chances are slim on that. I rarely leave my car sit for more than a week but when I do, I can tell the battery is somewhat struggling.

Keep in mind that these batteries do not like to be fully drained. They need constant recharging, else they can "sulfate" and then they are done for. Repeated draining will significantly reduce their useful life.

[Macknife]

Hi,  I have a 2003 LS430 with the same problem.  If I drive it every day or so it's fine, but If I leave it sitting for five days the battery is dead.  I replaced the battery and the problem persisted.  It's not the battery.  I never did discover what the slow drain is, but I figured out a solution.  I found a knife blade switch to put on a car battery.  It looks like the power switch for machinery.  I placed this in between the battery and the grounding cable.  It's built to install on vehicles.  When I know the car will be sitting for a week or so, I open the hood and disconnect the battery with the flip of this knife blade switch.  There is no battery problem now.  It's a slow drain, it has nothing to do with the battery.  What should really be done is the electrical drain should be located and fixed, however, I've never found any information on what is causing the slow drain.  I know this solution has kind of a baling wire/duct tape feel to it, but it's far easier than trying to find a really slow drain on the battery.

[John ADAM]

January 24, 2022

I have the same problem. 

The battery dies just after 3-4 days of inactivity. 
Battery, terminals, and alternator (both only 9 month old) checked out good by EXPERT mechanic. 
He thinks there is an electrical short somewhere and advised me to go to dealer which I am reluctant to do at $175/hour to diagnose and with no estimate on how long it will take (usual dealer trap) them to diagnose and fix.

I want to know some reasons for parasitic drain on 2005 Lexus LS 430 or in general.

Thanks.
John.

[madiro]

Hey John & Guys,

My 2005 LS 430 is having similar battery charge drainage problem. The AFS light is flashing so the thought is that perhaps this malfunction is shorting the electrical system . The dealer says drainage & AFS probably not related. Dealer also said that AFS no longer available in their inventory, car too old.
In Covid situation, I’m not driving as often . Dealer says that’s probably problem.  I’ve pulled the AFS fuse, light still flashing.

 I haven’t noticed any interior lights as cause. Stumped as to next step to solving battery problem. Any ideas ?

Thanks,

Paul

[Bykfixer]

My cd player, seat memory switch and dome light were the cause of my drain. The dome light comes from a door ajar module on the rear passenger side thinking my door is ajar. 

So bottom line is it could be a number of things but door ajar sensors would be a good place to start looking. 

[Igpoe]

For $13-$18 on Ebay you can get a solar trickle charger that will work with any source of 12 volts

Edited May 18, 2023 by Igpoe

[Steve Martin]

I have a 2004 LS 430.   I have had it since new. 125,000 miles.    I no longer drive it every day.   Sometimes, for no reason, the battery will die completely.  Other times it remains fine for months.   Here is what I just found out after all these years.  In the manual, it says if you lock the car, and do not use it for 5 or 6 days, the battery may be sluggish.  The smart key system uses power if the car is locked.   So does the key use power if it is close to the car.  My key was 30 feet away.  It went dead. 

They recommend turning the smart key system off which can be done using the button under the dash, above the gas pedal.

It appears the solution to the dead battery problem has been in the manual all along.   

[Igpoe]

At least you found the remedy. Thanks for posting this. No telling how many batteries this knowledge might save!

[MynehasWings]

I just encountered a similar problem. I have a 2017 LS460, bought in 2021. Only 42K miles. Because of recent medical problems, I had to leave the car parked for like a week. When I tried to start it up…nothing! This happened twice over a period of 3 months. I’m not sure if this is the original battery, and when I asked the dealership service tech, he says they couldn’t find any record of it having been replaced. So, it came down to me just pressuring them to test the battery, and they found one cell in it failed. I know very little about cars, but I do know when I have to be somewhere, I expect my car to help make that happen!  I’m due for more downtime. Should I locate that switch?