jjmurph01

Have a 2007 SC430. If we leave it undriven for a couple of days it seems the battery drains and we can't start. Have recently replaced the alternator; battery tests good. Anyone have any similar issues or have knowledge of what could be draining the battery when it sits undriven? Thanks in advance.

GmanSC

Do the search. Plenty of talk of this problem.
How old is your battery? If it's old, time for new battery.
Keep your battery under the tender when the car sits. It helps.

DJWLDW

GmanSC

I am not so sure about the whole battery tender thing if you have a good battery. We would leave our LS 460L in the garage without a tender for 3-4 months at a time while we were out in Hawaii living on our sailboat for the winter and never had a problem with the LS not starting when we got home. Is the battery drain any worse on the SC than the LS. They both have the red security light blinking regardless of weather the system is armed or not?

Dennis

Harold57

I agree with GmanSC, do a search, there's lots of information on this forum about this subject. However, for a couple of quick cursory checks:

• Make sure that all interior lights are off (usually related to the door or trunk or dome light switch)
• If you leave your light switch on automatic, try turning it off when you get out of the car
• Do you arm the security or leave it unlocked

If you are electrically handy, put an ammeter in series with the battery and determine how much power drain is going on. (You'll have to wait a bit after connecting the meter in for everything to power up and then resettle back down to idle.)
Also, do a load test on your battery (or have an autoparts store do it for you).

VVTiBob

For those of us who have a Luxlink modification AND who don’t drive the car regularly, a battery tender is a must have. I have killed two batteries, one was older, so I rationalized it. The other replaced under prorated warranty after only 3.5 years.

But I must also add this comment; my car’s original owner, who lived in Scottsdale, AZ, and did NOT do any modifications, had the original LEXUS battery replaced under warranty, less than six months and I believe it was about 5K miles into ownership of the car.

sightdev

I wonder if you have after market alarm system? I have noticed ML continues to draws power even after the keys are removed. slow draw is expected in modern vehicles so I do my best to drive the vehicle at least once every two weeks between three cars I have. with that note, i don't expect the replacement Lexus battery rated for 84 months will last more than few years with repeat draw down and charge back. disconnect or use batter tender for long term none operation.

oldbenz1

I also have an '07 SC (recently purchased) and had similar problems. Tried all the recommended fixes, but nothing worked. Finally replaced the battery and that has fixed the problem- at least for now. The battery was only 2 years old and was the best battery available. Considering that this seems to be a chronic problem with our cars, I think it's time to admit there's a design issue involved- why do our cars kill batteries? Has anyone had conversation with the right people in the Toyota/Lexus organization about this? Seems a recall may be necessary. Forget about your local dealership- their priority is to generate service department revenue thru issues just like this so we probably need to go higher in the company for satisfaction.

mandyfig

A Battery Tender turns out to be a recommended auxiliary item for our SC, no matter what the year and specifically if they are not daily drivers. Hence I have installed an adapter that makes it plug and play. In fact all my cars have them (the ones that are not daily drivers).

oldbenz1

I've owned more than 100 cars in my 67 years of driving- many, many makes and models. One of my favorites was an '02 Cadillac DTS, fully loaded with every option, even more electronic bells and whistles than my '07 SC430. I bought this Caddy new and drove it 125,000 miles in the 10 years I owned it. The original battery lasted 9 years and I NEVER had a battery drain problem, despite many times when it was not driven for several days. Likewise, I've never had a battery drain problem with any of my other cars in years past. It would seem that since 2002 battery technology should have improved, yet here we are with this chronic problem. Why do we have to keep a battery tender on hand and in use just for our Lexus cars? I really like my SC, but as I hinted in my earlier post, this inconvenience should be unnecessary, given the otherwise high quality of a $65,000+ car, I think it's time for Lexus, Inc. to get involved in this apparent design problem.

VVTiBob

Please feel free to get the ball rolling on this issue with Corporate. Typical dealer response is “behavior as designed”. Those of us with any electrical modifications, such as Luxlink, would certainly be excluded.

Harold57

Not all of the SC430s have this issue. I recently didn't start my SC for 9 days or so and it started right up without the benefit of a battery tender. We haven't fully determined what all causes some cars to have a higher drain than others, other than different settings and leaving interior lights on.

JTho

Thanks to this wonderful site, I knew going in that my 09 Pebble Beach could have this issue but I bought it anyway. At least my eyes were wide open.

Sure enough, went through 2 new batteries in just a few MONTHS.

When I bought it in 2017, it had what "appeared" to be orig battery in it. As a matter of course, I immediately changed it out to a new Interstate due to its age. I still don't know how in the world that orig battery could be in there and the car still working as it did.
Within a week, dead. Thought ok, maybe I got a bad battery. Let's try this again. Same thing but this time it died after 3 days. I have no mods on the car.

Had mechanic look for drain; couldn't find any. Installed a third new Interstate and a tender. Yes, a tender handles the issue, but honestly, I am irritated I should have to do this. What if I want to drive somewhere for vacation, park & not drive the car for a few days? Grrr. It's really the one thing that irks me most about this car.

But I love the car otherwise. So in addition to the tender, I have a portable battery jump / charger in case I do want to go somewhere & not have to worry I'll be stuck.

I did not have Lexus investigate; just my regular (very trusted) long-time mechanic. Maybe someday I will have Lexus look more into it. But I haven't been in a hurry as it doesn't seem others have solved this. I doubt Lexus will do anything since the SC hasn't been made for almost 10 yrs....

GmanSC

It definitely depends on the battery condition. I recently went on 3 weeks vacation, left the car sat without battery tender. To my surprise, the car started right up. The battery is year and half old.
But recently, the battery went dead just two week because I left the dome lights on, and it was under battery tender.

mewtoo

I have a 2005 SC430 purchased last August. It has Lexus battery (probably OEM but not original item). I only take her out once every two or three weeks. She always starts on the first crank. One time I left the dome light on and the battery was drained. I recharged the battery and it has been fine.

And I do not use a battery tender.

DshngDaryl

If you manually lock your doors with your fingers, you can get a lot longer garage sitting time out of your battery. By locking the car with your fingers (no remote and no lock button) you are physically locking your car, but not arming the alarm.

No alarms = Less secure, but much less battery drain.

After all, if it is in your garage, do you really need the alarm armed?