How do you test (catch ) an intermittent parasitic load o...

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Dean

Thank you Dean. You are going to have to pinpoint what is drawing the battery down. There can be a few different ways to do this depending on the set up you have. The first way is simple. Disconnect the negative battery cable from the battery. Put a test light between the negative cable and the negative battery terminal or post on the battery. With the key out of the ignition switch and the vehicle just sitting there (make sure the doors are closed) the test light should not light up bright. If it does, there is a draw. Then you remove one fuse at a time until the test light goes out. When it does, you have found the circuit that the draw is on. From there we can pull a wiring diagram of that exact or specific circuit and check each component on that circuit one by one to determine the root cause. Sometimes the [alternator](/topics-alternator-cadillac/) can go bad as well causing this condition. Yes even if it is charging when the [engine](/topics-engine-cadillac/) is running it still can go bad draining the battery when the engine is turned off. You would need to disconnect the BIG wire from the back of the alternator to see if the draw goes away. If so, the alternator is the root cause of the battery draw and will need to be replaced. On newer vehicles one of the computers or modules may stay awake or powered up for some reason. They can do this for a number of reasons. Faulty/sticking relay, wiring issue, faulty or insufficient input (like a door switch) or the module itself may just be faulty and need to be replaced. You can also use a multi-meter to check current draw from the battery. Anything over 100 milliamps is too much draw. The way you locate this is to start removing fuses one at a time until the meter drops to normal level. This will be the circuit with something staying on. Determine what components are part of that circuit and check them individually until the problem is isolated. Here is a YouTube video explaining how to check for a battery draw. [https://www.youtube.com/watch?v=lRcj1fQcWwU](https://www.youtube.com/watch?v=lRcj1fQcWwU) Glad I can help. Please let me know if you have any further questions. Thanks and have a great day!

intermittent parasitic load on a car batteryBattery is fully charged and is 3 days old. Battery passes the load test . Momentary steady state parasitic load, current drain, reverse leakage is 12.5 ma, yet the battery goes down to 50% overnight.Are you still there?

YES, I understand. You need to monitor the current draw on the battery at different times to determine when/if there is a draw

Ahhhh... were talking 48 hours here

Or you can use a meter that has the recording capability to do this for you so you don't have to stand by the vehicle the entire night to watch for this draw.

Now your talkingWho sells this kind of meter?

:). You are most welcome. Please let me know if you have any further questions. I recommend Fluke meters.

Fluke data logger is $3500.00 Can you recommend another lower cost solution?

The fluke meter I have was about $300, not $3,500. I do not know if any other company that makes a meter that has this feature but I am sure they are out there. You just need the record feature on the meter. You don't have to get a new one. You can even buy used. Here is one with the min/max record feature for much less. [https://www.globaltestsupply.com/product/tpi-153-autoranging-digital-multimeter-with-boot-and-test-leads?gclid=Cj0KCQiAoab\_BRCxARIsANMx4S5Vq231fR59o\_NmSVC\_QZUAtpxb-90M8zrKDDsRnbjnlDPHAQcAFyMaAkwHEALw\_wcB](https://www.globaltestsupply.com/product/tpi-153-autoranging-digital-multimeter-with-boot-and-test-leads?gclid=Cj0KCQiAoab_BRCxARIsANMx4S5Vq231fR59o_NmSVC_QZUAtpxb-90M8zrKDDsRnbjnlDPHAQcAFyMaAkwHEALw_wcB)