Parisitic draw

This is on my sons car so I don’t know the make and model but can find out if it makes a difference.

Battery went dead so he charged it up.
Battery is just over 1 year old.
Battery dead the next day so he charged it up but left the battery cables off.
Next day battery is still good so I tell him he must have a parasitic draw.

Today I took a test light over and put between battery negative post and battery cable. Light comes on so yes you have a draw.
We took each fuse out of both fuse boxes one by one but the test light never went off.
Yes we had the doors closed and everything turned off.
I disconnect the alternator as it is not on a fuse but test light never went off.
I am at a loss for what to try next.
 
This is on my sons car so I don’t know the make and model but can find out if it makes a difference.

Battery went dead so he charged it up.
Battery is just over 1 year old.
Battery dead the next day so he charged it up but left the battery cables off.
Next day battery is still good so I tell him he must have a parasitic draw.

Today I took a test light over and put between battery negative post and battery cable. Light comes on so yes you have a draw.
We took each fuse out of both fuse boxes one by one but the test light never went off.
Yes we had the doors closed and everything turned off.
I disconnect the alternator as it is not on a fuse but test light never went off.
I am at a loss for what to try next.
How about something like a lighted mirror on the visor light or a glove box light being on?

If posible, look the car over in total darkness for light from such a thing that's not turning off.
 
How about something like a lighted mirror on the visor light or a glove box light being on?

If posible, look the car over in total darkness for light from such a thing that's not turning off.
Trunk light, under the hood light. Find the power lead from positive battery (not the big starter lead) and disconnect that. Jim
 
You would be better off to use a good volt-ohm-meter than a test light. The light will only give you an on/off indication. I have no idea if that is sufficient to trouble shoot your problem. However a volt meter set to DCA on the 10 amp range put in series with a battery cable should tell you how much is being drawn as you disconnect each circuit one by one. A normal draw on a modern car should be between 50–85 milliamps. More than that will cause premature battery discharge.
 
You would be better off to use a good volt-ohm-meter than a test light. The light will only give you an on/off indication. I have no idea if that is sufficient to trouble shoot your problem. However a volt meter set to DCA on the 10 amp range put in series with a battery cable should tell you how much is being drawn as you disconnect each circuit one by one. A normal draw on a modern car should be between 50–85 milliamps. More than that will cause premature battery discharge.
That would be OK as long as the draw is not more than 10 amps.(very possible) Jim
 
That would be OK as long as the draw is not more than 10 amps.(very possible) Jim
This would be dependent on the capabilities of the ammeter. If it is only capable of carrying 10 amps of current you would want to place a 10 amp fuse in series between the cable and post to see if it pops the fuse to protect your meter before proceeding with connections to it. What I have also seen is a higher draw for a few seconds and then drops way down as if a capacitor has been charged. The ammeter method should eliminate this interference with your test. Also you need to disconnect the alternator wires, the main terminal definitely will not be fused. Well I should say at least they were not back in the day 1990s. Which brings up another point most new cars have a panel of heavier fuses under the hood. Those would also need pulled. Also since you said you did them one at a time that is not a complete test. You need to end up with no fuses left in the panel. Take a picture with your phone to speed up reinstallation. The ammeter would lower the possibility of this but for example, if one circuit had a low draw that the battery tolerated for say a week it still may be enough to light your test light. But at the same time another circuit developed an issue that has a higher draw that causes the battery to drain in one day. If you pull the fuse for the circuit that is the one day draw the one week draw circuit has the fuse you put back in you will never find the problem. In the end a total and complete test is reinstalling the fuses each by themselves only to complete each circuit individually. Also this should have been at the beginning, if your test light is a LED unit you will likely never determine which circuit had the draw, it only take milliamperes to light one of those. You need a test light with an incandescent bulb for this kind of testing.
 
There will be a 2nd fuse panel somewhere that provides continuous power to such things as the radio, clock,computers,etc. Usually in engine compartment. Also, if possible, check the specific gravity of each cell in engine he battery. I just had a 1 year old battery had a single cell fail, luckily still under warranty.
 
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This is on my sons car so I don’t know the make and model but can find out if it makes a difference.

Battery went dead so he charged it up.
Battery is just over 1 year old.
Battery dead the next day so he charged it up but left the battery cables off.
Next day battery is still good so I tell him he must have a parasitic draw.

Today I took a test light over and put between battery negative post and battery cable. Light comes on so yes you have a draw.
We took each fuse out of both fuse boxes one by one but the test light never went off.
Yes we had the doors closed and everything turned off.
I disconnect the alternator as it is not on a fuse but test light never went off.
I am at a loss for what to try next.
Not knowing make, model, or year yet, there is an outside chance he has one with 2 batteries. My 05 Benz does. I was getting charging alerts but the 'main' battery was fine and the charging system OK. Secondary battery is more like a lawn mower battery intended to keep vital function alive. That may be the source of the problem. I've heard anecdotally that many newer cars are like this.
 
The old ways of tracking down parasitic loads aren't that good for newer vehicles, since the normal power-off draw is so high. I think he should take his battery in and have it load tested, just to eliminate it as a possibility. Is the check engine light on? If so, scan for error codes; there could be a bad CANBUS device drawing current when it should be off.
 
Check out these vids , one of these videos shows how to find the draw ..https://www.youtube.com/@PhillipBailey
 
You would be better off to use a good volt-ohm-meter than a test light. The light will only give you an on/off indication. I have no idea if that is sufficient to trouble shoot your problem. However a volt meter set to DCA on the 10 amp range put in series with a battery cable should tell you how much is being drawn as you disconnect each circuit one by one. A normal draw on a modern car should be between 50–85 milliamps. More than that will cause premature battery discharge.
I am not real confident using a multi meter for this task.
I did hook up the meter using the setting 200m and it gave me an error code of the 1 on left side so I just put it away and used the test light.
So educate me because I want to try again using the meter because the test light may be reading the 50 to 85 m allowed drain.
My biggest setting looks like 5a.
What lead do I put on battery and what lead on wire.
I have used a multi meter to measure volts and ohms but never amps hence my low confidence level.
 
If it is a newer car it may take as much as an hour for it to go to sleep before testing. Body modules.
Some can actually take upwards from 24 to 48 hours during testing.

And you have sensors that do not have fuses such as crank sensors, cam sensors, fuel level, coolant level, washer fluid etc etc.
 
I am not real confident using a multi meter for this task.
I did hook up the meter using the setting 200m and it gave me an error code of the 1 on left side so I just put it away and used the test light.
So educate me because I want to try again using the meter because the test light may be reading the 50 to 85 m allowed drain.
My biggest setting looks like 5a.
What lead do I put on battery and what lead on wire.
I have used a multi meter to measure volts and ohms but never amps hence my low confidence level.
IMG_6651.jpeg
 
This is a situation where an older ammeter such as found
on a tractor comes in handy. A 20-20 ammeter with leads
& clips hooked from 1 battery terminal to the removed
cable will give some indication of the amount of current
that is being drawn. Then check where that amount of
current might be used.
Jim
 
First confirm the health of the starting charging system. No need to haul the battery to a parts store as they are lost and like most here lost when it comes to battery testing.


My god why do YT'ers fight a Multi meter.

 
I did hook up the meter using the setting 200m and it gave me an error code of the 1 on left side so I just put it away and used the test light.
If I understand correctly that shows that your load is over 200 ma. That may be normal right after you shut the car off as has been mentioned as it takes a while for everything to go to sleep. It might be helpful for you to find the draw on a higher scale such as the 5Amp you mentioned. You have a digital meter so you could put it on "DC Volts" the lowest setting and start measuring across the tops of the individual fuses. Even newer fuses have bare spots on the top where you can stick the voltmeter probes. A fuse that has current flowing through it will have a small voltage drop across it (mV). The ones that measure a small drop are the circuits you want to check. Again, some will draw a small amount of current all the time. I have found this method helpful in the past and you don't pull the fuses to do it.
 
First confirm the health of the starting charging system. No need to haul the battery to a parts store as they are lost and like most here lost when it comes to battery testing.
Hobo beat me to the fuse drop method with the how-to video. While the video doesn't recommend this method, I have found it helpful for the under-dash fuse panels when you have done the preliminary testing and have no idea where else to look. And yes, the door switches have to be disabled for the parasitic draw test, but some are not disabled by latching as the video shows. Some have a regular switch mounted somewhere on the door frame that the door activates. While the chart would be helpful it isn't essential for the fuse drop test. Any fuse with a voltage across it is worth checking out. I haven't used this method for the under-hood fuses. It would take a large draw for a 25 amp fuse to show much voltage drop so I agree that is probably not a good test in that case.
 

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