No Start Dead Battery

[wings91]

I got my new 06 LS in September, and 2 months later had a dead battery, no crank. I dismissed it as an open trunk.

About a month later, same thing. Again I charged it, but this time I knew nothing was left open.

Another month goes by, and I get a adjust parking brake warning, and notice the crank is very slow. Changed the battery again, and the warning went away.

I took it to the shop and after a 2 hour battery test they determined that it was bad and gave me a new one.

After reading a lot of posts here about this problem, I'm doubting that this is the root cause of the problem. Anyone have thoughts?

DAVE

 

[NYC LS8]

Sounds to me that something is drawing on the battery. Is there any aftermarket stereo equipment or alarm in the car?

 

[decibels5]

My interior lights dont work because I always have my doors open at car shows. With this being said it is very easy to turn your dome lights on and not even know it, especially if they dont work like mine. Just a thought. I have killed my battery a couple of times doing that. Also make sure your trunk light isnt staying on.

 

[HyeLifeLS]

The interior lights should go off automatically in 10 or 15 minutes even if they are on with the switch.

My interior lights dont work because I always have my doors open at car shows. With this being said it is very easy to turn your dome lights on and not even know it, especially if they dont work like mine. Just a thought. I have killed my battery a couple of times doing that. Also make sure your trunk light isnt staying on.

 

[decibels5]

After doing it a couple of times, I make sure my dimmer switch isnt in the on position (for the dome light). Every time this happens, sure enough, the dimmer switch is all the way on, allowing power to the dome light.

 

[mharrison]

Who can chime in with an "at rest" draw figure for this car? I don't know the factory spec on a current draw at rest.

But, You can put a multi-testor in-line with the battery (ie...inbetween the + pole of the battery and the +cable) and determine what your draw is. If you can get the factory spec on this then start pulling fuses, you can isolate the circuit that contains the draw. Then you break out the wiring diagram and see what is on that circuit and start unhooking individual components.

I just went through this with my BMW Z3. It turned out to be a bad seal on my antennae base leaked water on a factory sub amp, which shorted such that it worked fine, but was always on!

 

[beaups]

if you put a small multi tester inline like you suggest the minute any real current is drawn you'll probably just blow the fuse or fry your tester. get an actual ampmeter if you want to test this.

 

[mharrison]

The draw shouldn't be more than miliamps. Bear in mind that you are checking it at rest. You aren't turning anything on, and you definitely aren't trying to start it. This is everything turned off.

Mine pulled 272 ma. through the multi-tester with no problem. Factory spec was for <50 ma. for the Z3.
When I pulled the fuse for the correct circuit it dropped to 26ma.

I had no problem with blowing fuses or killing my meter....

This draw would kill my battery in a week after a complete charge. In a day on a partial charge:
272ma x 24 hours = 6.5A. 6.5A x 7 = 45.5 A.

This fine multi-tester was up to the challenge. And at $2.99 if you kill it, who cares?

 

[shokher]

you should have a battery with approx. 600 amps capacity. that is my guess for a stock battery. ii have an optima with 850a
so a 600amp hour battery / 45.5amps = 13.18 days. that doesn't account for the sleep mode the car falls into about 45 minutes after the car has been armed and nothing has disturbed it.


also if there is no load on a circuit (dome lights not in) then there is no power being used even if the switch is on. think of it this way: if you turn on your vacuum cleaner but it isn't plugged into the wall, how much power is it using?

 

[mharrison]

so a 600amp hour battery / 45.5amps = 13.18 days.

That would be 13.8 days until you have 0 amps. How many amps can you lose before the car doesn't start? Also I think you mis-understood. The draw numbers listed above were for a different car with an electrical problem. We don't know what kind of draw wings91 is having.

At any rate, the test with the in-line meter and pulling fuses will help wings91 determine where his excess draw is.

Do we still have nobody who know the factory specs for the draw at rest? I guess I can put a meter on mine tonight and determine what it's drawing.

Wings91, have you done this test yet?

 

[beaups]

you should have a battery with approx. 600 amps capacity. that is my guess for a stock battery. ii have an optima with 850a
so a 600amp hour battery / 45.5amps = 13.18 days. that doesn't account for the sleep mode the car falls into about 45 minutes after the car has been armed and nothing has disturbed it.


also if there is no load on a circuit (dome lights not in) then there is no power being used even if the switch is on. think of it this way: if you turn on your vacuum cleaner but it isn't plugged into the wall, how much power is it using?

Your calculation does not work. These batteries are rated in amps and cold cranking amps, not amp hours. I don't know of any public spec on car batteries that would provide an amp-hour rating in order to be able to calculate what you are trying to calculate. I can tell you if you drew 45 amps on a brand new 600 CCA battery you'd get a few hours max...not days.

 

[shokher]

That would be 13.8 days until you have 0 amps. How many amps can you lose before the car doesn't start? Also I think you mis-understood. The draw numbers listed above were for a different car with an electrical problem. We don't know what kind of draw wings91 is having.

At any rate, the test with the in-line meter and pulling fuses will help wings91 determine where his excess draw is.

Do we still have nobody who know the factory specs for the draw at rest? I guess I can put a meter on mine tonight and determine what it's drawing.

Wings91, have you done this test yet?

i agree on the method you recommend, that would be the cheapest way. but if you have one, a DC non-contact ammeter would be easiest so you don't have to insert you meter in series into the circuit. either way would do it though.

my mistake on the calculations i took the wrong # off the battery. the amp hour rating for the optima is 55ah. i measured my car to find out what the draw of a properly running electrical system on a ls is. after it goes into sleep mode it was 35ma. so this would still give you quite a few days.

 

[Justin00LS]

I have something drawing the current on my car as well. I am drawing .6 amp (600 ma) and my car will not if I let it sit for more than four days. I have pulled fuses on everything I've installed like system, gps, mirror, projectors, radar detector, etc..., I have even pulled numerous other fuses to try to isolate the problem. Does anyone know what the car should pull stock? I am guessing 25ma or less.

 

[mharrison]

From the previous post it looks like 35ma. is a ballpark.

You need to methodically pull fuses one at a time until you find the big draw. Then hit the electrical diagrams to determine what is on that circuit.

 

[macboy]

Before trying to diagnose this problem, you must understand a couple of things. First of all, the car has a "Standby" mode and a "Power Down" mode. The car goes into Power-down after about 45 minutes of inactivity (no doors opening or closing, no keyfob activity etc.), and is woken up into Stanby mode if the doors are unlocked or opened, etc. And you need to know what current draw numbers to look for.

I have a TSB covering diagnosing battery drain. It basically says to do what mharrison suggested. In standby mode, the drain should be around 850 mA (0.85 A), and in power-down mode it should be about 35 mA (0.035 A). It mentions that removing fuses 2.20 or 4.14 will wake up the car when in power-down mode, causing the current draw to jump.

Note that in addition to the fuse boxes under the hood and in the trunk, there is one in the right front kick panel, called the central junction box.

Needless to say, if you do not know what you are doing, you shouldn't even be trying this.

 

[mharrison]

Before trying to diagnose this problem, you must understand a couple of things. First of all, the car has a "Standby" mode and a "Power Down" mode. The car goes into Power-down after about 45 minutes of inactivity (no doors opening or closing, no keyfob activity etc.), and is woken up into Stanby mode if the doors are unlocked or opened, etc. And you need to know what current draw numbers to look for.

I have a TSB covering diagnosing battery drain. It basically says to do what mharrison suggested. In standby mode, the drain should be around 850 mA (0.85 A), and in power-down mode it should be about 35 mA (0.035 A). It mentions that removing fuses 2.20 or 4.14 will wake up the car when in power-down mode, causing the current draw to jump.

Note that in addition to the fuse boxes under the hood and in the trunk, there is one in the right front kick panel, called the central junction box.

Needless to say, if you do not know what you are doing, you shouldn't even be trying this.

This is great information. Thanks for posting it! I wonder if there is a way to force the vehicle into power-down mode. I would think a provision for that would be programmed in to allow for troubleshooting. I wonder what the purpose of the power-down delay of 45 minutes is... This seems quite lengthy.

I don't have an electrical diagram handy at work. Does anybody know what circuits fuses 2.20 or 4.14 are for?