Battery charge life.


Active LVC Member
Mar 31, 2011
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Collinsville, OK
Approximately how long should an 01 3.9 L battery keep enough charge to start car after sitting. Fully charged battery will only last about 9 days until down to about 11.5 to 12.0 volts. Haven't been able to find any major drain problems. Approx. what should the amp drain be when car is asleep?
The spec says less than 0.05 A (50mA). In practice, it should be 20 to 30 mA. Note that after you connect the meter, you have to wait about 30 minutes for the car to go to sleep. You can't open/close any doors or press any buttons during that time. It is okay to leave the trunk or any door open.
The battery should be good for about a month.
Thanks for quick reply. Is there any way to keep car from waking up when putting meter into circuit? My meter doesn't like ma settings when first connecting it because the draw is too high until car sleeps. If I use a higher setting, it won't show the lower ma draw when it does sleep. I am connecting between battery and ground cable. Any better way?
No way.
Put a switch in parallel with the meter. Close the switch and make the connections. Wait 30 minutes, set meter to mA, and open the switch.
No way.
Put a switch in parallel with the meter. Close the switch and make the connections. Wait 30 minutes, set meter to mA, and open the switch.
That was my thought but I wasn't sure if that would cause the car to wake up again when the switch was opened which would blow the fuse in meter again. Only have the installed fuse left and didn't want to chance blowing it. Thanks again and I am very glad you didn't leave this site when you got rid of your last LS.
I get a week to ten days on mine if alarm is armed. Unarmed, I may get 14-20 days before it won't turn over. I even get this on a new napa gold battery, but I just run a float charge on it when I know it is not going anywhere. Last week, after sitting only 2 weeks, alarm unarmed, I went to check on it, and it did not respond to the key fob. Sure enough, it was flatter than a flounder. Not even an interior light could turn on.
What I use is a clamp on DC ammeter. Until I got mine chasing these tiny current drains was a nightmare as you found out. It is worse with cars that go to sleep as that just adds hours to your troubleshooting!
Plus it's SO MUCH nicer and quicker to clamp the meter on without disturbing anything! The clamp on type's are safer as measuring current with an in-line setup is likely to blow up your meter sooner or later. Just not great to run current thru your meter unless you have professional grade meter's like a Fluke.
But make sure you get one that can read as low as joegr mentioned up thread.

They have come down a good bit in price since I got mine and you need a meter that can read 10ma drain or smaller. I have a GTC CM100 but that's a pretty good/expensive meter. There are much cheaper ones that should work too. Here is a $50 meter that will go down to 1 ma.
Clamp on DC Ammeter

If the car is operating correctly with no drians it should stay charged for a long time. I now have a 2014 XJR Jaguar and they are widely known for battery problems like the LS is. But I left the car at the airport for over 6 weeks and had no problems starting even with a 5 year old battery.

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