I6turbo

iTrader: (1)

It's apparently a fairly common thing. My '03's battery wouldn't start the car after about 14-18 days of sitting in the garage with nothing "on." It happened once on the original battery and once within about a year of buying a high-CCA, high-rated aftermarket battery (DieHard, IIRC).

tromly

This is interesting, I'll have to ask the dealership's service manager if he's ever heard of the locks draining the battery.

Lexie's LS

The Lexus dealer exchanged the battery at no cost, said the alternator was fine. A vendor who sells both trickle chargers and charge protectors (that cut off the battery before allowing it to fall below crank range) opines that a trickle charger would be the better way to go for these newer vehicles loaded with electronics. If the charge protector keeps shutting down your battery, clocks, etc., would have to be reset each time.

There is a solar trickle charger that includes a desulphater. It is purported that this device feeds a small amount of amperage to the battery (in sunlight) while desulphating the battery plates for longer life. But the simplest models--just trickle chargers--rest on the dash and plug into the lighter...very non-technical for people like me.

rcpeters

I have had those dead battery problems on both cars, so I bought one of those $60. jump start batteries and keep it in my garage. Using the cars at least once a week, and making sure the lights are set on auto, no problems.

Lexie's LS

Update: dealer's exchange of battery under warranty appears to have worked so far. No issues, strong cranking power. Still keep jumpers in the trunk. Will forego any modification to cigarette lighters (need constant power for trickle chargers) for now. Car works like a charm. Had a brief issue with smart key, but I think the steering wheel was incorrectly set when parked.

FisforFast

Women are common perpetrators when it comes to dead batteries, I believe this is a well known fact.

AlexusAnja

ha ha... "a well known fact"... I'm taking a wild guess that you're not a woman

It is interesting to know that the lights DO NOT go off when in "ON" position with car turned off. Can others confirm this? I have mine on auto all the time and have gotten into habit of hitting the lock button twice to lock and turn light off immediate.

framer1

Have same problem with my 02 ls.Two batteries probably not needed. Two trips
to dealer no help there told to have it hauled in when dead again.Think i
might have figured out the cause.Went to school play one hour long came
back dead battery.Discovered i might have hit trunk unlock when we left.
Haven'T had that checked yet.Must have something broken in there.Any thoughts on that.

V8_Fan

You can have the dealer change the personal settings so the lights turn off immediately when locking the door.

brandyd

I've had the dead battery issue with our '94 LS 400 and again with the '01 LS 430.

Here's how to diagnose it.

1. measure the "at rest" battery drain. ( a previous poster mentioned this as well).. remove the negative battery terminal.. connect a meter in series between the battery negative and the (removed) negative cable.. set the meter to read miliamps. At rest battery drain should be less than .060 amps.
2. if you measure more than .060 amps then first make sure everything is off... i.e. ignition (well duh!), interior lights (close the doors) , mirror lights, trunk light.. hood light etc.
3. once you're sure you've eliminated any additional drain battery then grab your owners manual... flip to the back section under fuses. For example, the '01 LS 430 has a mere 85 fuse/breakers... located in 6 seperate locations (no, I'm not making this up).
4. while following the manual start removing fuses one at a time and monitoring your meter... once you've located the offending circuit then you'll have to decide replacement/repair etc.
5. additional tips:
- do one fuse at a time.. replace it before you move on to the next. (greatly reduces anxiety inducing "now it doesn't work" syndrome.
- follow the fuse diagram.. .verify the correct fuse rating for each slot. The previous owner/mechanic etc may have swapped "whatever was available"... this is just a good common sense check & peace of mind. Sometimes a mechanic (bad/dumb one) will swap a higher rated fuse to try to mask a problem i.e; replacing a 10A with a 15A. This is not only a bad idea but dangerous (can cause circuits & componentry to fry).
- spare fuses & fuse puller are (usually) located in one of the engine bay fuse panels.
- the automatic seat belt tensioners are typically the cause of excessive battery drain in Mercedes... not sure if this is common to Lexus as well.
Good luck!

V8_Fan

LS draws quite a bit of power when you are not using it. It's best to get a deep cycle starter battery like the Odyssey. Standard starter batteries aren't designed to be continually drained and recharged. If you leave your lights once a couple of times or don't drive few a couple of weeks, your starter battery will not be able to fully recharge while a deep cycle can. Anyways, when I leave town, I disable the smart key and connect the battery to a trickle charger. Another thing: if you lock the door, the car will be constantly searching for the smart key, which uses more power.

caddyowner

Doesn't it always look for the smart key anyway? If I'm loading my wife's wheelchair in the trunk, I have to remember to grab the smart key off the key rack so I can use the button on the trunk lid. Without the smart key, the trunk lid button doesn't work, even if the doors are unlocked.

LS430inDE.

Excellent observation.

For troubleshooting using the pulling fuses method, I would also remove whatever fuse(s) protects the SmartAccess and/or security system before measuring for the baseline reading.

Obviously those systems will always be using power, so disconnect them to observe if there's parasitic drain coming from another system.

framer1

Still plagued with battery going dead. Lexus dealer no help.Carrying around
battery pack and jumpers seem ridiculous for $50,000.00 car.If it wasn't
such a good drivin car i would go back to GM products at least i could
count it to turn over.I also blamed my wife for the dead battery. I was wrong.
Sounds like nobody here has a solution to the problem.2 trips to dealer,
2-batters later.Same

I6turbo

iTrader: (1)

What did you find when you ran brandyd's test above?