rnourse

I stumbled across this post while researching a dead battery problem with my sc430. Battery dies if I leave the car sit for longer than 2-3 days.

The funny thing is that I had no problem finding scads of people in this forum (and others) that have this issue with the sc430. It's very very clear that I'm not the only one this has happened to. Yet strangely there are these random posts that say "there's no inherent problem with the sc430" and "nobody else has this problem so it must be you or something you've done".

To those who would argue that because they haven't seen it, there is no such problem I would suggest doing a quick search in the sc430 area for the keyword "battery". Look at all the results and ask yourself... If there's no problem, why are there so many darned threads about dead batteries?

1NICESC430

I've read of these battery problems ever since Day One and I do believe that some of you do have a problem.

Perhaps all of those who have had battery problems should start a thread discussing what they all have in common. There are many many more SC430 owners who have not had any battery problems whatsoever.

I've had my 2002 SC430 since the summer of 2001 and it still has the original battery. I've garaged it from around November until around March every year since I've owned it and used a BatteryTender to keep the battery charged. During the months when I drive it, there are periods of three or four days when I do not drive it and do not have it charged by the BatteryTender.

So the question is why is my battery (or car) different from yours and all the others who have had battery problems? What do you all have in common?

tfischer

I also have never had a Battery Tender, and have owned my SC since April of '01. This car sits for many winter weeks without being driven, and always starts up.
I replaced the original battery a few months ago, which is a good long life for a battery.
No car should drain the battery in just a few days, and no car would last on the market if that were "normal" for that car. No one could put up with that. Many people park their cars for days and weeks at a time without driving them.
If you battery is dead every 2 or 3 days, then something is wrong with the car or the battery.

rnourse

Now that would be the million dollar question wouldn't it?

bubblerboy

Now I will tell you that I had a 1992 SC400 which would do this when left alone for a period of time. The thing that I found odd was as follows. I would get into the car (after sitting for a month) and the cars electrical system would be stone cold dead. Nothing when the key was turned. I had a battery operated jump starter which I would hit it with and it would fire off and run fine. It was never that big of a issue, sold the car and the next ower uses a trickle charger but the thing that seemed "Odd" to me was that the battery was not completely drained. Once it was started that first time after sitting and driven a short distance it was OK. It was as if the car would shut itself down when the battery got to a certain point. I do not recall that the memories of the radio and seats etc were affected. The car would not start and there were no clicking sounds when the key was inserted but the battery was not as stone cold dead as it appeared. Not certain this is any help at all. I thought I was the only one with the problem. Because of the way I used the car I was able to work around this. I can't see how this could not be resolved. It's not rocket science. Once you eliminate that battery itself and the charging system then what else is there but some type of drain on the system. Can anyone come up with another 4th factor other the a haunting? I always assumed the techs could fix this it I wanted to bother apparently its not that easy. But it has to be some type of drain correct? I also was a little suspicious of the battery connections which I think some one else did mention. What would the jumper be doing which seemed to bring it back to life. JEH

Drewmo

I also 'suddenly' started to get this problem, that the battery wouldn't turn the engine on my '02 SC430 if left for more than three or four days. I suspected something bad; however, the dealer assured me it was just the battery. I very suspiciously coughed up the $150 for a new Lexus battery, and I noticed the difference immediately - the engine seems to turn over twice as fast as it used to when I crank it. Not that I had noticed it getting slower (had the car since new), but even after I had charged the old battery overnight, it would not crank as fast as the new battery does!

The car now stays up when not used, so in this case the battery was the culprit. But before I succumbed to the dealers diagnosis I did check out the car myself for 'off' drain. I measured about 40milliAmps (mA -1/1000 of an Amp) of drain (after an initially high ~300mA of drain for about a minute or two, apparently while the computer is wondering whether this is just a pause, or whether the car is really off).

Would 40mA be enough to flatten the battery? Lets say the battery is a 60Amp-Hour battery (I'm not sure what exactly it is): that means it can supply roughly 60A for 1hour, 6A for 10Hrs, or 60mA for 1000hrs. So at 40mA, the battery should theoretically last around 1500hours - ok the battery would be dead then, not much use to start you car - so lets say half that long, or about 750hours.

750hours is about 30days. So if my math is about right, a good car, with a good battery, should last about a month before it won't start. If your car is not starting after a week or so, but starts well when frequently used, then either:

1) the battery is knackered or at least tired, and won't hold a full charge
2) there is excessive drain when the system is supposed to be off (quite possible with the sort of computer systems we have in the car these days controlling whether things are on or off
3) the battery is not being kept charged correctly. This can fall into the camp of either not supplying enough charge to suit the load (too much load / not enough charge capacity), or too much charge that is frying the battery (faulty charge system) and thus accelerating the demise of the battery. But if the car normally starts and runs ok when used frequently, it kinda suggests that the charging system is topping up the battery. Only if the car was problematic in starting at random times would it suggest bad battery connections, or poor charging.

It is therefore pretty essential that you have someone who knows about electrics fix these kind of problems with an accurate diagnosis, rather than a 'mechanic' (no offense intended). A dead battery may be just a symptom (ie over-charge/under charge) or, as in my case, the actual cause.

One other thing, I've heard and can attest to the fact that the original Lexus batteries were not much cop and had less than a 5year life. The latest have a 7year warranty. I guess they have had their share of complaints and made some changes as a result.

FALCON1

As a new forum member I have been reading the battery thread.

Here is my take, I own a 2002 SC 430 since birth. My first battery died at 20,000 miles and 4 years into operation. I do not use the Lexus every day.
Service told me that it is an "inherent" design problem where this is the only model that the alternator does not charge the battery UNLESS the car is in motion??????? Lexus replaced the battery under warranty.

Now some 19 months later the 2nd battery dies............flatbed comes out and Lexus replaces the unit and then wants to charge me $225. for the battery and $150. for the flatbed.
I did a circle dance in the managers office and we both called Customer Care in So. Cal. They agree even though it was out of warranty to pay the tow and the battery THIS TIME. I told them NEXT TIME they will too or I will never buy another Lexus again. No matter what the J.C. Powers Polls show.

Hope this adds some spin to the thread.

FALCON 1

Pearlpower

iTrader: (2)

Thanks for sharing, an example of an misinformed Lexus service person. I have checked my charging system a few times in the past. Charges the battery and system just fine at idle. No car would stop charging the battery if not in motion.

Now if the a/c, lights, stereo, fan full blast, nav on, etc.. were all on at idle then yes, very few cars out there would charge the battery sitting still.

FALCON1

Funny thing about the statement is that it came from Lexus Corporate not the service writer.................Hell, my Benz has more computers and electronics with brakes and suspension controls the the SC and I have zero battery problems.

The new LEXUS $200. battery is made in SPAIN..........not even a U.S. DIE Hard unit...............go figure.

FALCON 1

Philiptou

have you tried to remove the Radio#1 30A fuse for the Mark Lavinson Amplifier? I did that and I can start the car after it has been sitting for more than 20 days now. I need the instructions to take out the amplifier to prove it drains the battery because of its internal fault.

Philiptou

I think I have the same problem. I diconnected the Radio#1 30A fuse, and I can start the car now.

loveslexus

iTrader: (2)

Whats the biggest baddest battery that will fit in the SC with the highest CCA?

Seems like batteries for this car are a hidden secret.

barncat

Will a battery tender extend the life of a battery? Seems like it should.

SC43052

Absolutely.

Short life in a battery is almost always due to sulfication. Sulfur crystals form when the battery sits unused for extended periods and the battery is not at full charge. Normally once the car is operated and the battery is brought up to a full charge again, the crystals dissolve. If the battery is maintained at full charge sulfication does not happen.

A low charge battery can be because a number of reasons, including the driving habits of the owner, parasitic current draw, a failing alternator or a bad connection in the electrical system.

Starting the car drains the battery. Driving 2-3 block won't bring the charge back to full. Multiple short trips around town can bring the charge down to 50-60% of a full charge as each restart draws more out of the battery, which doesn't get replenished.

If the car is an occasional driver (as many SC430s are) then the car may sit for a week or two before being used again. The longer sulfur crystals that are formed sit on the charging plates in the six battery cells, the harder they solidify until eventually they are permanent, and block the recharging of the battery. The battery begins to die.

Another scenario that will cause a low charge is parasitic current draw. There is a specified closed circuit current that Lexus designed the car to maintain in order to run the remote door locks and anti-theft system while the car is at rest. All other power consumers such as the main computer and other equipment by design should go to sleep. But not all vehicles meet the manufacturer's design and some have a substantially higher closed circuit current draw that can quickly deplete the battery. And of course as battery sulfication forms due to sitting for extended periods at low charge, the shorter the battery will last when parasitic current is drawing at the battery.

A charger is a very good investment to maintain a battery's health, whether the low charge is due to short trips, infrequent use, parasitic draw or a combination of all. Keeping the battery at full charge will stop sulfication and greatly extend its life.

A good charger will handle either a flooded lead acid battery or absorbed glass mat type. The SC430 uses an FLA type due to the battery's location in the engine compartment. A good charger will have three or four separate charging intervals to insure that battery life is maximized, and these types can be safely left on indefinitely and will not overcharge the battery. Good quality chargers are in the $50-$100 range with Schumacher and Battery Tender being good quality names.

The charger can be used daily or occasionally and can be set up with a quick disconnect cord with connectors that go under the battery cable clamps on the battery terminals, with the quick disconnect end exposed at the front grill so the hood doesn't need to be opened to hook up the charger. Or traditional battery spring clamps can be used for more occasional use.

barncat

Wow! Thanks for a GREAT explanation!