dead batteries

My 2003 SC430 has the same problem. It is really bad in the winter, if I do not drive it everyday. I heard somewhere it has to have Lexus battery, does anyone know if this is true? Or any ideas, suggestions, would be much appreciated. Thanks! Coralville, Iowa

I have a 2002 Lexus sc430 that I purchased in 2004. I have gone through, what will be, my 3rd battery. Lexus dealer says because I don't drive enough and since the car runs on a computer-based system it constantly drains battery regardless if I drive or not. I put it to the test and started driving car at least once a week and didn't have an issue then when I stopped driving and had let it sit longer I had to jumpstart every time then eventually it goes completely dead. Seems like everyone with this car doesn't drive it constantly and so everyone has the same problem. The dealer did suggest for me to unplug the red cable from battery if I don't drive but I get too lazy to do it. However, on my this next battery I will do that since each battery is about $150!

It's easier to install a battery tender which will trickle charge the battery when you arent driving the car and all you simply have to do it hook it up to the battery, and when you are done driving the car and its going to sit for a while, plug in the connecter to the tender. tender stays with the car.

Not sure if anyone is still following this thread but I have a couple solutions. 1. Turn off the automatic light switch. The one that controls the headlights. Our dealership told us that that has a constant draw on the battery. Since we turned it off, no issues. 2. As kyle stated above a battery tender, but you can set one up that uses solar power and is always in the car. It doesn't take much to trickle charge the car and you can actually make one yourself for quite cheap. This way, you're not plugging it in and unplugging it when you want to drive; it's "behind" the scenes. Just so everyone knows, there isn't a "Lexus" battery. A battery puts out volts and amps, the car does not know the difference between two batteries that put out the same power. I hope this can help someone. My issues are with the alignment. 5000 miles ago my wife had a blowout (we knew it was coming) so I replaced all tires and upgraded rims. 5000 miles later, front tires replaced again!!!! @ $240 per tire, this is rediculous!!! Anyone else have alignment issues? my email is LCLEVERSLEY@hotmail.com

Alignment issues are common because lexus has to put so much camber into the car to make it stable at higher speeds it just eats tires. the 2010 and older IS and GS have the same problem. Really no way around it since i believe camber is nonadjustable on the SC

thanks for the response. wasn't the answer I was hoping for.. LOL.. but it is what it is. It just doesn't make sense because when we bought it, the tires that were on it lasted a long time but 5000 miles!!?? ugh.. irritating.

Best answer is to avoid directional tires, and avoid run flat tires. Run flats are extremely hard and tend to wear funny and without directional tires, you can rotate them properly and remove the cupping that wears into the tire and remove the edges and road noise..

yeah, the run flats I won't buy, but I didn't even think of the obvious with the directionals.. thanks man. I'll have to keep that in mind for the next set of tires.

I have had this problem...it was a boomerang anti theft device. Once it was removed by the dealer...no problems again...

Also when storing our 2006 sc 430 for the winter I put a trickle charger on the car at 2amps....does the trick just fine. ..

We have tried both a trickle charger (didn't work) and disconnecting the battery (didn't work this time--Summer 2017). My car was last driven 2 months ago and then the battery disconnected. I have had to replace the battey several times on my 2006 Lexus SC430. I do engage the "automatic light switch" all the time so maybe I will also disengage that when I leave. I never have had problems when driving the car in the winter down here in Florida because I drive it almost every day (even if only short distances). The Triple A guy said yesterday that disconnecting the battery isn't the answer either as the battery begins to deteriorate somehow anyway. I guess either I will have to buy a different (and I hate to do this as I LOVE this car), or resign myself to getting a new battery more often then would seem necessary.

I have a 2002 sc430 which has gone through many batteries. A tender solves the problem. SLH

We also have a 2002 SC430, same battery problem. Evidently the latest battery was the wrong one, installed by a battery shop. So, my cousin installed a switch in the wiper well that completely shut down the car. Flip on when starting, flip off when leaving. worked for a couple of years, then I assume the battery just went. Took the car to an electric place. Everything checked out, they said that that switch should not be used and took it out. So sorry I let them do that as it was the only thing that worked. Called AAA and bought a new battery(correct one) when they came to jump the car. That battery worked for a year or so and now it doesn't. Took it to Lexus, they charged the battery and checked it out, said no need for a new battery. Two days after a full charge, dead again. I put it on a trickle charger as we always do if not using the car for a while. Just waiting to see what happens.

I also have a 2002 SC430. I can not leave it sit for a week and the battery goes dead. I have went through several over the years! I do not have the auto light system on, either. The Lexus dealer says, "put a trickle charger on it." Really. ..A friend has a Mercedes hardtop convertible similar and Mercedes has a battery in the truck separate from cranking battery. They have a drain problem, also. What else is causing this? If it is the security system, I will disconnect it. OzziesSC430

Sell the car and buy American...much cheaper, not finicky and realiable

Having the same battery problems on my 06 430sc. Was told didn't drive it enough. Battery was replaced due to accident involving door close mechanism. New battery fixed it for a while.. about a yr later same old problem. This time did a drop voltage test was done(because it came in from the bodyshop not a direct customer complaint) and was told that wire on the radio system was causing the problem. Supposedly fixed New battery...same thing 3 months later. Frustrating...even my Harley is more reliable after sitting than this thing!

Ugh - thanks for all your responses. Just bought a used Lexus SC 430. Drove it 550 miles home and parked it for a week and now it won’t start. Car was to be a gift for my mother’s 70th and it is sitting in my garage like a paper weight. I’ll turn the auto- lights off and look at a trickle charger after I change this battery. Glad I found your posts prior to giving. Her the keys to a dead car.

2002 Lexus SC 430. Love the car but have the same electrical problem as all of the above. Burned out the battery from sitting. Would charge to 13 volts, but lost voltage as soon as under load. Replaced the alternator. just replaced the battery and keep the car on a tender all the time. Great car other than this electrical drain. Did notice that when I connect the battery cable, there is a bigger spark than any other vehicles. Will try not using the auto headlights and will disconnect the auto theft.

Ensure the battery terminal wires aren’t loose. Had that issue with 03 sc430 from the get go but once I installed terminal spacer have not had any issues. They usually give you a 550CCA battery. That is too weak to handle all the electronics in vehicle so once I switched to 725CCA or anything over 625CCA you shouldn’t have anymore issues with car dying out on you for long periods of non driving.

Always leaving my SC 430 which is a 2006 on a trickle charge when I would be away from my home sometimes weeks at a time seem to always work.This past week I had an absolutely dead battery AAA came out and jumped it and said all the batteries fully charged and then the next morning after I drove 10 miles was dead so I am going to buy a battery when I get back to Florida with more power anybody has any other guesses let me know

I have a 2004 SC430 with the same battery drain problem. I systematically went through my fuses measuring battery current after each fuse was pulled. You have to shut the doors and wait about 10-15 minutes for the current draw to reach a minimal state with all the computers and floor lights to shut down. The car was draining 150 mA from my battery when not being used. After much time and effort, it turns out that the telephone computer was pulling 100mA. With that fuse out, the current draw dropped to 50 mA, which is still not great but much better. Since no other systems seemed to be affected, I just left that fuse out. Still use a battery tender when not using the car for several days, but hopefully this latest battery won't die within a year.

Purchased a 2003 SC 430 about 4 months ago. I’m on my 3rd battery. Now I have the car I will try the charger others have suggested. But the main point is Lexus designed this defected vehicle and they are doing nothing about it. I’m sure disappointed in this company. This is my 4th Lexus, no problem with any of them but this one.

I get a mysterous battery drain about once every 3 months. I can't find the leak. I gave up and put a switch on the positive battery terminal. Every time I park the car overnight I pull the switch. When I close the switch and start up, all I have to do is set the clock.

I recently bought a used SC430 and also experienced the battery drain issue, finding my battery frequently drained, even if on a 1Amp trickle charger (OK on 3 Amp charger). In my case, it was an improperly closed trunk, which appears to have kept certain power systems alive and thus caused as much as a 1 Amp drain. Once this was addressed, the power consumption in "sleep mode" (car shut down) dropped to 0.05 Amps (50 mA). I was planning to check circuit by circuit, pulling individual fuses, but in the end did not have to do so. In reality, though, It appears there are too many scenarios in which the power drain remains too high. To note, if the car draws 300mA per hour, it will drop half its charge in just 5 days. I will kepp monitoring my situation to make sure that there are no other "issues".

I no longer use the master switch I installed on the positive terminal on the battery. I now use a full battery charger (no trickel charger) that is on while my SC430 is parked at home. If my rare battery leak happens to kick in, the amount of power my large charger puts out is enough to prevent the battery from draining down and keeps it full, which I have been told will extend the life of the battery greatly. Putting the charger on may seem to some to be a hassel, but just pretend you own an EV !!