Saturday, June 19, 2021

Measure battery drain

 If you suspect battery drain and want to measure the current consumption, you have to do things right when measuring. As long as the car is not in sleep mode, you will always get unusual high readings. Here is how you should do it...

Connect the ampere meter right. Never connect the ampere meter between plus and minus - you will short circuit the battery. The ampere meter should be connected between minus on the cable and minus on the battery, after du have disconnected the cable - like this picture:


The battery is in the rear trunk. Here is the catch: As long as you have the trunk door open (or any other door), you will get high readings. Some of the explanation is because of the trunk interior lights. Some have disconnected the lights, but this will not solve the problem. You can wait a long time - but still have unusual high readings because the car will not enter sleep mode while one or more doors are open. Here is how you fix this:


Push the lock mechanism until you hear a click. Open and do the same for the front doors, so that you have access to the fuses. Now the car believes that all doors are locked, and will enter sleep mode after a short while. Wait 10 minutes to ensure the car has entered sleep mode. If you open any door lock afterwards, the car will wake up from sleep mode.

If your ampere meter has an average reading mode, now is the time to activate it.


Here is a normal reading after the car entered sleep mode. The readings fluctuated between 10 and 30 mA, and that is a good reading. If the car has not entered sleep mode, you will get readings that is at least 10 times higher.

If you get a reading that indicates a battery drain, now is the time to investigate. Check the lamp in the glove box and sun visor. Pull and reconnect one fuse at a time to find the source to the drain. You have fuse panels in the engine compartment, by the steering wheel and in the trunk.

Remember to unlock door locks before closing the doors.