igorxx

Parked my 2002 sc430 with 6 month old battery at airport for 10 days while I was out of the country. When I got back the battery was dead. It was easy to jump and the clock was still on. I could see nothing that was left on. Any ideas, I have seen some other cars that have had the problem, something about theft lights, gps etc. I drove it home about 30 miles and have had no problem since.

SC43052

You may not see the problem again if you don't leave it sit 10 days. And you won't know unless you measure the battery voltage and alternator output. Alternator output should be between 13.5 and 14.2V depending upon engine RPM.

Every modern car has some current draw while the car is idle, primarily for holding settings in memory, operating remote lock systems, anti-theft systems etc. Most automobile power system designers shoot for 30-40 ma draw, but sometimes it goes higher. The higher the percentage of battery charge you start with before you let the car sit, the longer the battery will last and still start the car. If the alternator is not fully charging the battery or if there is a defective battery cell (can happen in even new batteries) then you are not starting with a full charge before the car is shut down.

A 6 month old battery fully charged should measure around 12.6V+. For a normal system that goes to sleep after starting at 12.6V or more, the battery should last 20-25 days in most cars.

If you can leave the car sit for a few days, measure the battery voltage after it has sat at least 1/2 hour. Then measure every 12 hours over a couple of day period to see if it is dropping. 12.4V is around 50% charged and 12V is around 25% charged.

If the battery voltage is dropping significantly over several days first think about any add-on aftermarket equipment. If you have none then you may have to do some more sophisticated system current measurements to see what current is flowing through the power system while the car sits at rest.

sorka

This is a common thread with this car. My battery will be drained in 10 days as well. My alternator is charging at 13.6 volts. My battery is new.

Using my Fluke 77 to measure the current draw, the following fuses take:

DOME = 2 ma
MPXB2 = 5 ma
MPXB3 = 10 ma
MPXB1 = 15 to 25 ma (varies wildly)

9 ma is being drawn when I disconnect pretty much every fuse except the main, so I still don't know where that one is coming from.

Total is around 50 ma continuous draw or about 12 ah over 10 days.

kjcole

Yes, we see this type of thread popping up much more commonly than in many other cars, it seems. I've had this happen to me (7-10 days), with no electrical mods. However, when I changed spark plugs earlier this month I noticed the 5 year-old Lexus battery had a dry cell, which means my (infrequent) problems may relate to that battery issue. With colder nights (and an unheated, detached garage) now it seems like it cranks a little slower (I'm off to Walmart later today to pick up a battery - their Maxx H6 size). I'm sure that the car was designed for longer hold periods - but I'm suspicious that the safety margin against sub-optimal battery performance or alternator output is thin. Checking the starting voltage, and voltage losses overnight and longer without driving, would be one way to document an issue, as the previous poster suggested. One theme in these threads is that investigations for higher-than-specified current draw come up empty. That leaves the battery and charging systems as the prime suspect. For comparison, I have three Ford vehicles (2000, 2001, 2005) and a Chevy (2009) - mileage between 85K and 170K - and none of them show this issue.

Habious

Whenever we go on vacation for more than a couple of days, I always put a trickle charger on the Lexus the night we get back....and it usually takes the charger 12-14 hours to bring the battery back up to 100%ish.

I know the battery will have run down while we were away (but I'm paranoid about burning our house down by leaving the charger plugged in the entire time we're away).

Also, if we're driving to the airport and leaving the car for the duration of the trip, we always take the wife's car. I know mine will be dead when we get back if we're gone more than 3 or 4 days.

Just...how it is with my SC430 (but I've got a bunch of aftermarket crap installed in my car - LuxLink, CarPC, etc.)

mandyfig

Hence a trickle charger is a very important piece of equipment. I am amazed that if I hook up the charger, it will stay charging for a day, means the battery charge was not optimal. I use the SC once a week, sometimes 2x. But for short runs.

reelbb

My SC is a weekend car and I usually don't have any problems starting it up even if I skip 1 weekend. However, I noticed when we left the country for 3 weeks, the car wouldn't start even with a 6 month old Optima redtop installed. These cars definitely have a electrical draw even sitting in the garage.

I agree with the other members, a battery tender is a great economical way to keep the battery alive.

FLYCT

Here's a repost from one I made several months ago. I use Battery Tender JR's any time I don't expect to use the SC430 for more than 3 or so days. I have a 2007 and a 2008 SC430. It seems perhaps the pre 2006 models drain batteries faster, or so my dealer said.

"Starting up a SC430 and driving it just a few miles 2 or 3 times a month is not enough running time to fully recharge a battery that has been drained due to parasitic drain and cranking the starter motor. All that the few miles of driving will do is provide a surface charge. Eventually the battery will fail.

Keeping it fully charged with a smart charger such as a Battery Tender Plus or Battery Tender JR will extend the battery life significantly.

The only way to accurately check parasitic drain is with an ammeter. These cars draw about 50 ma of current when parked and turned off. I've measured current provided by my battery tender JR to maintain battery after fully charged. It puts out 47 ma to maintain voltage by providing current necessary to replace parasitic drain.

A battery tender JR will slowly (0.75 amps or 750 ma) bring voltage up to 14.2 vdc or so and then switch to float mode to maintain voltage at about 13.0-13.1 vdc. It can take a few days at 0.75 ma to top a battery off and for the charger to go to float mode. It took me 3 full days to get a previously fully charged battery that was sitting for 6 weeks to go to float mode. When I initially measured the resting voltage after 6 weeks it indicated the battery had lost 75% of its charge.

A Battery Tender Plus will do the same thing but time to fully charge will be reduced by about 1/2.

I've used smart chargers on my cars, motorcycles and aircraft that are not used frequently. They work very well to extend battery life.

JR"

mrblister

I have a 2005 and have used Battery Jr plus since new still on oem battery.

76210Guy

I must be a lucky guy because I traveled constantly on business for the past three years since I got my SC and many times it sat in the garage near the airport for more than 2 weeks at a time and I never had a dead battery (knock wood).

barncat

I've put 5000 miles on my 03 since I bought it 18 months ago. It's been in the garage for over 2 weeks many times and I don't know the age of the battery. Never had a problem. That said, now I've probably cursed myself!! LOL

mandyfig

Battery tenders during winter time is a must.

Vh_Supra26

iTrader: (1)

I was told to start it up once a week.

dd24

Hi,
I wanted to chime in because I am having the exact same issue, but to a greater extent.
I have checked alternator and battery all is good.

Using test light with ignition off, doors closed it stays lit until I pull the MPXB1, B2, B3 fuses....then test light will die off.

Pulling the d/c cut fuse essentially will do the same thing and cause test light to quit.

My battery will drain exceedingly fast here in the last few months.

Battery normally around 12.4....with those three fuses intact it drops to 12.1......

I have TIS documents and such, but feel that isolating this problem will be a major headache.....guess I will have to pull apart dash to find the issue.

Anyone have any suggestions or ideas how to handle this better?


Would also like to add that Advance Auto states the diode pack in the alternator is bad, but other mechanics say alternator is fine and I can see it puts the battery up to 14+ when car is running.

Could, if the diodes are bad and the car is off be the source of the draw?

barncat

Just bought one on Amazon for $45 w/ free shipping. Figured I had to after my last post here!