As long as I've had this car, about 10 months sometimes, after 4-5 hours or overnight, the battery is mostly discharged and unable to start the car. These times I found a door open or the dome light left on or a dashcam left on. It seems to me these a fairly low amp draws and a good battery should handle those kind of draws for a few hours or overnight and still maintain a decent charge. I've had the battery checked 2-3 times and each time it was declared good. Terminals have been cleaned. So maybe there is a hidden power draw I'm not seeing? I have some troubleshooting skills so would appreciate some advice. I have a multimeter if that is of any help to troubleshoot this irritating issue.

 

Need to know ,
Do you know how to do voltage drop testing?

 

No but I'll see if there is a Youtube video. I followed video and found no voltage drop from battery terminals to connectors. But that only shows me that I have a good connection. How do I determine if I have an unseen draw on the battery?

 

The old method was not reliable.
After you use the vehicle you prepare when in sleep mode,(45 min to an hour) the vehicle, so ABSOLUTELY NOTHING changes That means drivers window down so you don't have to open any windows, Door latch for diver's side door `Fuse panels where you can access them with the meter,. You measure the voltage drop over each fuse
It will be (milliamps) the one with the biggest voltage drop is the circuit involved. If you pull out ANY fuse the system could reset the system and you will never find the problem.
It's a little bit of work and that is why many places don't want to get involved. Don't forget as long as the problem has not been allowed to reset, that circuit is under load and if you take your time , you should find the problem. Can you do this?

 

I'll keep this info handy for future reference. In the meantime I was told the even though the battery has checked good several times that it still can be in degraded condition due to having been discharged deeply several times. I will buy another battery then test it by leaving the dome light on for 4-5 hours then seeing if it will start.

 

If the battery was tested properly and tested good, no need to spend that $$$ on another battery . At this point installing a new battery and doing the test you describe will not help find the original problem.

Many times folks use the rear wiper and for some reason it cannot come to the correct park position and shut off. Check that to make sure there is no problem back there.

 

Check any light which may be hidden like glove box light or a hood light staying on draining the battery.If you find a warm device, bulb, or motor, it could mean its been energized for a while. Is your charging system working properly? You could try disconnecting the battery use your ohm meter to check for a low resistive path to ground from the disconnected positive cable and your ground.Example, an alternator with a shorted bridge rectifier can drain the battery.If you have a low resistive path to ground, you could also try removing fuses one at a time till the low meter reading goes away. That will atleast provide you some troubleshooting direction.I would try this first before looking for a logic issue from the computer energizing a circuit which can get complicated but is less likely to happen.

You won't measure any actual voltage drop across a good fuse, unless the fuse is blown and that itself won't drain your battery.A good fuse will have the same voltage present on either side of it.

 

I read recently, a few folks mentioned that their rear windshield washer was not returning to resting place and the attempt to go back was causing their batteries to drain. Check the motor on the wiper in back, if it is warm or hot it may be an issue??

 

Using an ohmmeter to check connections, is USELESS. WHY?
If you have only 1 strand of wire connecting the circuit , the meter will read continuity (0 ohms) and yet the circuit will not handle any kind of current, so don't rely on that faulty reasoning.
If you are going to do drop testing the circuit MUST be under load and you measure between specific points.

If you try to measure between the battery and a cable end , you just opened the circuit and allowed the system to reset and you cannot use that reasoning either.

The methods suggested earlier that include preparing the vehicle so no circuits are opened and you check the drop across the fuses.is the better way to find the drain..

 

Even though tested good several times at auto parts stores I replaced the battery last month. Have had no issues with it since.