? for you LRH mechanics, How much voltage drop overnight is OK in a car?

[HockeyDad]

Have an 07 Accord. Couple months ago the battery died a couple times. Jumped it and checked the voltage while running and the alternator was throwing 14+ volts, so that's good. Bought the battery from Costco, so took it down and exchanged it for a new one.
Yesterday, the battery died again. Jumped it and got it home and the voltage yesterday afternoon was 12.6. Just went out and checked it this morning and the voltage is 12.38.
Is that a normal ovewrnight voltage drop due to alarm, onboard computer etc, or does it sound like I have a short?

 

[Winkfish]

If you have a clamp on amp meter that will help you in determining if you have something that is drawing down the system. If you can determine how much parasitic draw there is in the system when it is "off" you may then be able to determine have a bad ground or a circuit that is placing undo load on the battery when you think it is off. Your battery is falling down to a little less than 75% of maximum capacity overnight, that is a little much. You should also be able to have a local auto parts store do a load test on the alternator. It may be putting out the correct voltage however it may not be capable of producing enough current to get the battery back up to 100% during normal driving conditions.

 

[Taylorbok]

How to Find a Parasitic Battery Drain: 11 Steps (with Pictures)

If your vehicle is drawing power from the battery and all of the lights and other electrical components are off, you might have a parasitic battery drain (or draw). Luckily, you can usually find the cause of a parasitic draw yourself....

www.wikihow.com

This is a decent guide.
My old lady had an 09 Accura MDX that developed a draw. Turned out to be the bluetooth module, it wasn't worth replacing so I just unplugged it and carried on with life.