BlakeFL

I'm going to start diagnosing my parasitic draw tonight. We're not using the car much lately because of Covid and after sitting about two weeks the battery is completely dead. What should the typical draw be after the car is sitting for awhile with all doors closed? I bought a Noco battery charger/maintainer to at least keep it from going draining completely while I diagnose the issue.

Arsenii

Hello,

To check if you have parasitic draw, be sure to have as little turned on as possible, then disconnect the negative battery terminal, and connect an amperemeter between the negative side of the battery and your negative terminal. Let it sit for a second, since your amperage may jump up a little, but then it should drop close to zero. If not, start pulling all the fuses one-by-one until the value would drop. That would mean that the faulty system is now deactivated, and you will have to diagnose the system to which this fuse belongs.

The other method is to check the voltage drop across a fuse. Every fuse has its own fixed resistance, hence there is always some insignificant voltage drop occurring, and the more current you are trying to push through it, the more losses there will be. In short, all fuses has exposed leads on top of them, set your multimeter to Millivolts and measure the voltage across the fuse using those exposed leads. Here you can find a chart that will help you determine how much current is going through that fuse based on the voltage readings you get.

Hope this helps and best of luck!

LeX2K

You need to wait 30+ minutes before checking (put your amp meter inline then wait), this makes sure all the modules have gone to sleep. Typical draw is about 60 milliamps.

BlakeFL

Thanks @Arsenii and @Lexus2000. I will post my findings after I investigate further.

Oro

Parasitic draw tests are hard. And usually useless.

If the car has been sitting, you have diagnosed it 90% right there. batteries don't do well sitting. Short drives don't charge them and it's a never ending cycle.

I revivied two "dead" batteries this past month with a de-sulfater and then strong charge. Desulfate the battery and then fully charge it, then load test it. One battery that was fully dead (would not take a charge at all) was only two years old, but sat three months. It was a cheap battery (Pronto). The other sat over nine months as I figured, but was high quality (Volvo OE). It was five years old but came back to 95% capacity after desulfating repeatedly, re-charging and after load testing.

I have in fact had parasitic draws, but given what you said, look at the battery, how batteries work, and focus on it before going down a different rabbit hole.

BlakeFL

Seems like you were on to something @Oro . According to my clamp meter, when first connecting the battery it spikes to around 50-60ma but then after awhile settles down to around 20ma. Not sure if that is too low or an incorrect reading but I did not see it jump after 10-15 minutes while checking to see if it was an intermittent load. Seems like the cheap Walmart battery that it came with just can't handle sitting for long periods. I have the car in the garage now on the Noco Genius 2 so hopefully it doesn't happen again. Next job is the timing belt.

Oro

50 to 60 ma is the high end of acceptable for newer cars. 20ma is more like regular for a 4es.

If you do not have a desulfater or complicated charger/starter, just hit it with high voltage a while w/an old school charger (not TOO long). That will help desulfate it and "wake it up." I know that sounds off-the-cuff and ridiculously old school, but it does work and makes physical sense.

I know I asked before but where do you live in Fla? (I lived in Clearwater a while when young, my parents and family there and other places longer).

BlakeFL

The Noco claims it has battery desulfator so hopefully it ran through that process when I first charged it. I'm in Central Florida.