Need help with battery drain

[flat-top]

I have a 96 Maxima. The battery is good and alternator is charging at 14V. When the car is off there are two circuits in the engine comartment fuse box with 12V pulling on them: the battery/ign fuse and the power window fuse. Any ideas on how to better isolate the problem?

[sbddude]

Check each fuse with an ammeter (current setting on a multimeter) with the car off. Anything with a significant current draw is your culprit.

[SCREIST]

Originally Posted by flat-top

I have a 96 Maxima. The battery is good and alternator is charging at 14V. When the car is off there are two circuits in the engine comartment fuse box with 12V pulling on them: the battery/ign fuse and the power window fuse. Any ideas on how to better isolate the problem?

Does it drain the battery overnight so the car won't start? How quickly does your battery discharge? I have a similar trouble with a 1992 Nissan. To determine if the actual amp load on the battery I use a clamp on dc amp meter on the negative battery terminal. Having 12 volts at a few fuses while the car is turned off is probably normal. Anyone know what the actual current load on the battery is supposed to be when the ignition & accessories are turned off. Just the radio memory, clock? security system etc.

SCREIST in South Central PA

[Nahkapohjola]

Originally Posted by flat-top

I have a 96 Maxima. The battery is good and alternator is charging at 14V. When the car is off there are two circuits in the engine comartment fuse box with 12V pulling on them: the battery/ign fuse and the power window fuse. Any ideas on how to better isolate the problem?

Use your multimeter amp scale to measure how much the drain is.

Battery is 60Ah =ampere hours

If you measure 1 amp current draw, that means you have 60 hours and then battery is totally dead. At 48hours maybe no start any more...

Very simple math:

1A x 48 hours is 48Ah

60 Ah minus 48 Ah leaves 12 Ah for startup.

From this one can see that 0,5A current draw is about top limit, or bigger batt is needed. I think problems start is draw is more than 0,2A - 0,3A.


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Take one suspect circ fuse off at a time for overnight. The one causing prbl drain, should be inspected...

1. What is batt voltage 1 hour after you stop?
2. What is batt voltage in the morning?
3. What is batt voltage when u start?

[flat-top]

It does drain the battery overnight, in fact it will drain the battery in an hour so much that the engine will turn over a few times when starting, but it's not strong enough to actually start the engine.

[Nahkapohjola]

Originally Posted by flat-top

It does drain the battery overnight, in fact it will drain the battery in an hour so much that the engine will turn over a few times when starting, but it's not strong enough to actually start the engine.

Measurements:
1. How much is voltage att batt while idling
2. What is voltage when you stop engine
3. What is voltage ½ hour after you stop engine

4. if you take batt terminals off at [2.], is there any difference at (3.)

5. While inserting batt terminal back on, is it sparking liberally?

Healthy battery dies with all lights on in 'bout three hours. Devices capable of sinking more energy are starter and shorted alternator (one hour drain). Its either of them, or your batt is not full in the beginning.