13.7 volts at battery at idle too low?
05-16-2018, 11:03 AM
#16
Electron Wrangler
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Alan
05-16-2018, 11:21 AM
#17
Electron Wrangler
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Lifetime Rennlist
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To measure your parasitic drain, you will configure your multimeter for amps, highest range to start. Remove the negative battery terminal. Connect the plus(red) meter lead to the battery terminal with a clip. Connect the neg(black) meter lead to the end of the heavy cable lug with clip. This will put the meter in series with the current flow to the battery. You will need to close all doors, and hatch and wait for about 5 minutes for the timed acc circuits to end. Note down the reading. Then start pulling fuses, and keep testing the same way. Note any delta when fuses are pulled, and what they serve. Most likely culprits are int lights, radio, alarm.
There are loads that are switched based on power status, disconnecting the ground turns those off (e.g. fan after running, window controller head units etc). Install the meter while the battery ground is connected. Connect the meter from the battery ground connection on the battery to another ground point - there is one behind the panel above the battery in the tire well (behind the plastic panel - forward of the battery in the car). Drive the car, park, remove the battery ground strap from the battery ground point behind the tool panel. This way you never lose the battery connection. Don't change meter ranges to avoid losing the connection that way also.
I suggest pulling the rear hatch light switch connector so the interior lights don't come on (under the hatch receiver), then you can leave the hatch open as you test. Tape the door pin switch closed so you can leave the passenger door open too while checking fuses. Start with 10A range to ensure the meter is safe. Then do it all over again at a suitable range till you can work at the 200mA range where you can see what is really going on. It requires a methodical approach - be thorough, create a table and document your findings as you go.
Anyway here for the OP - sounds like it's your battery that has real issues - seems like it's time... broken batteries can self discharge due to internal issues (lose plates inside etc).
Alan