Power Leak and Battery Voltage at Rest

[hari-bhari]

What is the voltage of your battery after about a day of not driving? Mine dips to about 12.0V. Still no problem starting the car (I just upgraded to a Red Top), but it seems like that's on the low end. I thought it should stay around 12.5. I have already upgraded to a 130A highlander alternator and done 2/3 of the big 3 upgrades (alt to batt and batt to ground) and I rechecked all my grounds for the sound system which is only about 700W. I am not getting any hiss so I know my ground connection is not bad. With the car running I get about 14.1 to 14.2 volts on idle, and then immediately after turning it off I get about 13.0 volts. However by the next morning I am down to 12.0 volts. Any ideas on what could be causing this? I'm scared to leave my car even for a few days without driving for fear of a dead battery.

edit: sorry this may belong in the non-aftermarket forum.

[gnegroni]

I thought the battery was supposed to go down eventually to 12v while the alternator is not running. Alternator ON voltage of 14.1 or 14.2 is excellent. I don't see anything wrong with your system.

[hari-bhari]

from what i have read it should hold at 12.5 volts....

[TadS]

Yeah you should be at around 12.6v. I would pull the battery from the car, and see if it goes down on its own. If it does, you may have a bad one, if not you're probably getting a draw from something else in the car.

[hari-bhari]

its a brand new battery and my last one did this too, so i know its not the batt. where do i go about finding a leak?

[TadS]

A good automotive electrical specialty shop.

[Eye8Pussies]

start pulling fuses and then leaving the fuse out over night...then check the voltage the next morning, and repeat until you find the right fuse and then start diagnosing it with a voltmeter to see what the draw really is

or you can just go around to each fuse and check with a voltmeter with the car is off as well and see which part of the electrical system is drawing power when it shouldn't be with the car off

[gnegroni]

Yeah you should be at around 12.6v. I would pull the battery from the car, and see if it goes down on its own. If it does, you may have a bad one, if not you're probably getting a draw from something else in the car.

Normal batteries should stop at 12.6v, but Optimas to something somewhat higher:

The following Optima batteries should be charged to 12.8 volts: 34 / 34R / 34/78 / 6V / 34M / 75/35.

The following should be charged to 13.0 volts: D34 / D34/78 / D6V / D34M.

Either way, it looks like you might have a leak then. Take it to a shop if pulling fuses results inconclusive.