Parasitic draw

How to test for a parasitic draw on battery? My 2007 has one I think. I need more information and knowledge of how to test it. It had an Interstate battery in it, not even a year old, sat for a week and wouldn't start. So I believe it developed a bad cell. But before when I drive it daily it was just fine. Just replaced that battery with a brand new Interstate one via warranty coverage from Costco and now getting it inspected, which is why it had to sit. Ideas please

 

Unhook one of the battery leads and put a voltmeter in line between it. One end to the battery terminal the other to the battery post. So all power flows through the meter.

With the key off and the truck sitting measure amp draw (current) then go back after and hour and check the reading.

The truck has about a 15min timeout from when the key is off until it’s puts all the ECUs to sleep/low power.

Basically you are checking for amp draw when the vehicle is sitting. If it’s to high you know somthing is still “on”

 

Also after the truck has been parked for an hour or so walk around it to make sure no dome lights or cargo light or anything is still on.

 

Also, want to make sure the hood is closed when doing that test....

Most latches have a sensor which will draw a small amount of power when unlatched.

Same with doors.

 

Many home use meters will be unable to handle that initial load.

To measure current and not pop the fuse in your meter, you have to place a shunt across your meter temporarily.

Disconnect Negative battery terminal and place a jumper wire between the terminal and the cable to take the initial load of powering electronics up. Leave it there for a minute or so. Now connect your amp meter to the same place and remove the jumper wire so the meter can measure current.


OP - are you saying it killed the new battery too? If not, maybe it was just a bad battery.

If it kills the new battery, get the alternator tested. Diodes can go bad and they'll happily discharge your battery.

 

If I had my craftsman multimeter setup right, I didn't get a draw with the negative cable disconnected at all. But I do remember when I had the previous battery in there, I took the negative line from multimeter and touched different area on top of the battery itself. Now the battery was dirty, on one area by the battery cap on the positive side of the battery I did get over 1.5 volt charge. I cleaned the battery off and check again and there was no charge. I had seen this on a video somewhere and even on this new battery I did the same thing and no charge either. So all of that dirt and crude on top of the battery was drawing over 1 volt from the dirt which contains lead. Also I am trying to use the multimeter to measure miliamps, red lone is in red hook up and th3 negative is in the com port. It is a craftsman 82141 meter