12v Battery Phantom Drain

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leaferone

Member
Joined
Dec 2, 2020
Messages
5
For the past few months, I've been having a phantom drain on my 12v battery in my 2011 Nissan Leaf. It goes dead after just under a week of sitting idle. I've monitored the voltage and it steadily drops over time (going from about 12.50 to about 12.20 in a day, for example). A current meter consistently indicates that there's a 0.19amp draw. The TCU is unplugged, and pulling fuses from under the fuse box under the hood does not help (though I have only tried the regular fuses and also haven't touched the passenger compartment fuse box).

Here's the weird thing. This always happens, and has for months. But when I took it to a Nissan dealer, it sat there for nearly a week and they claim it only lost a trivial amount of voltage (0.02v) in that time. I am just baffled by this. Why would it consistently drain at home, but not at a dealer? I can't think of a reason why they would lie about it (they're turning down work to fix the problem).

Any ideas for what could be causing this or why it might behave differently based on location?

Thanks in advance!
 
It may be the same phenomenon that makes so many problems non-reproducible at the dealership, and also makes cats and dogs seem to magically get better on the nightmarish ride to the vet. It's some kind of cousin to Murphy's Law. Something like "No problem that can temporarily improve will be reproducible under conditions in which it can be diagnosed and fixed." You could try driving the same distance as the trip to the dealership, with the car being parked at your house again at the end. I would also suggest a hardwired battery maintainer lead, with a fairly robust battery maintainer...
 
leaferone said:
But when I took it to a Nissan dealer, it sat there for nearly a week and they claim it only lost a trivial amount of voltage (0.02v) in that time.
Click to expand...
The terminal voltage of a battery depends on temperature as well as state of charge and a few other things. That could mask a small drain, although 0.19A isn't a very small drain, especially over a week.

So I agree with Lefty that it's likely an intermittent fault, perhaps triggered by temperature, slope of driveway, etc. I would have said that the TCU is the #1 suspect, but you say it's disconnected.

though I have only tried the regular fuses and also haven't touched the passenger compartment fuse box...
Click to expand...
Since you can make the fault and the dealership can't, I think that's your next option. Fuses are a very convenient way to isolate faults like this.

Note that there are some drains that come on for around 5 minutes after you open a door, then drop to nearly zero. That can drive you crazy if you're not aware of it. You may need to defeat the door switch for the fuses that are only accessible from the doorway. Often just unscrewing it from the metal chassis will be enough, but beware of bumping it and creating a second intermittency to mask the intermittency you are chasing. Don't just pull the interior light bulb(s); various computers are triggered into higher current operation by the door switch, so you may as well leave the interior light in place as a visual indication of the door switch status.
 
I noticed this was the OP's first post.
Has anyone thought to ask the model/brand of his 12v battery, or how old it is (because it definitely isn't the stock battery after 10 years)? Or if anything in the car has changed recently (because this apparently wasn't a problem a year or two ago)?
 
Thank you all for the replies so far.

LeftieBiker said:
You could try driving the same distance as the trip to the dealership, with the car being parked at your house again at the end.
Click to expand...
Alas, I already tried replicating the distance and actions involved in driving to the dealer, but to no success.

LeftieBiker said:
I would also suggest a hardwired battery maintainer lead, with a fairly robust battery maintainer...
Click to expand...
I've been using a battery maintainer with camps, but have now ordered some alternative leads to make the process easier and more stable. Thanks for the idea.

coulomb said:
So I agree with Lefty that it's likely an intermittent fault, perhaps triggered by temperature, slope of driveway, etc.
Click to expand...
I'll try to replicate the temperature and slope from when it was at the dealer (colder and slightly more inclined than when it was in my garage). Seems unlikely that a colder temperature would remove the drain, but I'm willing to chase any leads at this point.

coulomb said:
I would have said that the TCU is the #1 suspect, but you say it's disconnected.
Click to expand...
Yes, the power cable is disconnected. I also pulled the fuse just to be absolutely sure, and that made no difference.

coulomb said:
though I have only tried the regular fuses and also haven't touched the passenger compartment fuse box...
Click to expand...
Since you can make the fault and the dealership can't, I think that's your next option. Fuses are a very convenient way to isolate faults like this.

Note that there are some drains that come on for around 5 minutes after you open a door, then drop to nearly zero. That can drive you crazy if you're not aware of it. You may need to defeat the door switch for the fuses that are only accessible from the doorway. Often just unscrewing it from the metal chassis will be enough, but beware of bumping it and creating a second intermittency to mask the intermittency you are chasing. Don't just pull the interior light bulb(s); various computers are triggered into higher current operation by the door switch, so you may as well leave the interior light in place as a visual indication of the door switch status.
Click to expand...
Appreciate the advice. I will try to pull those fuses when I next have some time to work on the car.

Stanton said:
Has anyone thought to ask the model/brand of his 12v battery, or how old it is (because it definitely isn't the stock battery after 10 years)? Or if anything in the car has changed recently (because this apparently wasn't a problem a year or two ago)?
Click to expand...
The 12v battery was replaced about 1.5 years ago and worked fine for a long time. When this started happening, I had it tested under load and it performed fine. The battery holds a charge fine when it's not connected to the car. But most significantly I've verified that there's a drain via a clamp current meter, so the health of the battery can't be the issue. I saw many threads about battery issues when I first started researching this, and eliminated that possibility first off. No changes to the vehicle. Thanks for making sure that I didn't miss these possible issues.
 
leaferone said:
But most significantly I've verified that there's a drain via a clamp current meter, so the health of the battery can't be the issue.
Click to expand...
I hate to suggest this, but I don't know your level of expertise with multimeters. DC clamp current meters are usually of the Hall effect kind, which notoriously have zero offsets and sometimes drift. Did you zero the display before clamping? If not, you might just be reading the zero offset current of the meter, not an actual drain. You can confirm a suspect reading by clamping in such a way that the current goes through the clamp in the other direction. It should then read about the same value, but with opposite sign (negative versus positive). Averaging the absolute value of the readings improves accuracy and confidence.

Sometimes, especially in electric vehicles, there are stray electric fields about, which can also affect the reading. Try moving the clamp around near where you intend to clamp, without a wire in the clamp, and note the reading (which should be zero). Consider clamping the other battery cable, or at a different position. If your clamp meter had two current scales (mine has 40A and 400A), consider using the higher current scale. In my case, I get much less drift and offset on the higher scale. 0.1A resolution is often all I need.

If you are aware of all this, then apologies, but it's another possibility we can eliminate.
 
leaferone said:
Thank you all for the replies so far.

. Thanks for making sure that I didn't miss these possible issues.
Click to expand...

Do you leave the key fob in or near the car?

Leaving key fob in car can drain battery

https://www.mcall.com/sc-motormouth-autos-0616-20160613-column.html
 
Many of us have installed those hardwired battery maintainer leads with the socket terminating in the charge port compartment, so only the charge port has to be opened to connect it. I had my 2013 set up that way for about 4 years, and will be doing the same with the 2020 SV+. I'll drill a hole in the plastic port mount panel, use a rubber grommet, and if the car gets turned in rather than kept, I'll replace the grommet with a black rubber plug. I did something more primitive than that with the 2013, and it was never noted.
 
coulomb said:
I hate to suggest this, but I don't know your level of expertise with multimeters. DC clamp current meters are usually of the Hall effect kind, which notoriously have zero offsets and sometimes drift. Did you zero the display before clamping? If not, you might just be reading the zero offset current of the meter, not an actual drain. You can confirm a suspect reading by clamping in such a way that the current goes through the clamp in the other direction. It should then read about the same value, but with opposite sign (negative versus positive). Averaging the absolute value of the readings improves accuracy and confidence.

Sometimes, especially in electric vehicles, there are stray electric fields about, which can also affect the reading. Try moving the clamp around near where you intend to clamp, without a wire in the clamp, and note the reading (which should be zero). Consider clamping the other battery cable, or at a different position. If your clamp meter had two current scales (mine has 40A and 400A), consider using the higher current scale. In my case, I get much less drift and offset on the higher scale. 0.1A resolution is often all I need.

If you are aware of all this, then apologies, but it's another possibility we can eliminate.
Click to expand...
No offense taken at all. It is helpful to rule out all the possibilities. I don't have a lot of experience with these kinds of tools (I'm a DIY'er, but with no training and little experience). But I am confident that I'm using the meter correctly. I do zero it out, right next to where I'll be using it. Depending on how close I am, how much time passes, and how I wiggle it, it can vary from 0.18A to 0.20A, but that's still fairly consistent. I've also tested it on other vehicles to make sure my meter is reading correctly (it is).

ydrape said:
Do you leave the key fob in or near the car? Leaving key fob in car can drain battery
Click to expand...
Key fob is nowhere near the car, so that can't be it. But thanks for making sure that wasn't the issue anyway.

LeftieBiker said:
Many of us have installed those hardwired battery maintainer leads with the socket terminating in the charge port compartment, so only the charge port has to be opened to connect it. I had my 2013 set up that way for about 4 years, and will be doing the same with the 2020 SV+. I'll drill a hole in the plastic port mount panel, use a rubber grommet, and if the car gets turned in rather than kept, I'll replace the grommet with a black rubber plug. I did something more primitive than that with the 2013, and it was never noted.
Click to expand...
It is frustrating and depressing that such a tactic is necessary. But this is a great idea for making the situation less inconvenient. If it's as easy as drilling a hole, inserting a grommet, and running the line through, that shouldn't be a problem. If I have to take anything out to get access to the right spots, though, I may chicken out :)
 
It is frustrating and depressing that such a tactic is necessary. But this is a great idea for making the situation less inconvenient. If it's as easy as drilling a hole, inserting a grommet, and running the line through, that shouldn't be a problem. If I have to take anything out to get access to the right spots, though, I may chicken out
Click to expand...

Yes, it is unfortunate. The one upside is that you can get into a routine of plugging in both the EVSE charging cable and the maintainer cable once a week, and it isn't much extra trouble. There is no need to remove anything. You don't want to use the Negative terminal on the 12 volt battery, though: use the bolt on the upper right side of the PDM stack - aka the thing that looks like an engine head and valve cover. I will post a picture with it circled if you need one. EDIT: there are two candidates on your car, as shown.

OTQSjl1l.jpg
 
I had an intermittent 12V battery drain on my 2011 that was caused by one of the little relays in the box up high under the hood on the passenger (right) side near the firewall failing to drop out when the car was turned off. It took me a while to find it, but the power draw you are describing is about the amount I had so it would discharge the battery if the car sat for too long. Try tapping on those relays one at a time to see if your current draw goes away. Replacing the little relay fixed my problem until the car met its demise. The relay should have been covered by warranty, but only if I could reproduce the problem at the dealer so I just bought a new relay and plugged it in.
 
leaferone said:
For the past few months, I've been having a phantom drain on my 12v battery in my 2011 Nissan Leaf. It goes dead after just under a week of sitting idle. I've monitored the voltage and it steadily drops over time (going from about 12.50 to about 12.20 in a day, for example). A current meter consistently indicates that there's a 0.19amp draw. The TCU is unplugged, and pulling fuses from under the fuse box under the hood does not help (though I have only tried the regular fuses and also haven't touched the passenger compartment fuse box).

Here's the weird thing. This always happens, and has for months. But when I took it to a Nissan dealer, it sat there for nearly a week and they claim it only lost a trivial amount of voltage (0.02v) in that time. I am just baffled by this. Why would it consistently drain at home, but not at a dealer? I can't think of a reason why they would lie about it (they're turning down work to fix the problem).

Any ideas for what could be causing this or why it might behave differently based on location?

Thanks in advance!
Click to expand...

Ok the power usage is not consistent. You have several events that will increase the draw. Your 12 volt is charged by the LEAF regularly. Problem with this is the battery is never fully charged and runs on an algorithm which we can only guess was determined based on "normal" usage of the car. Your driving to the dealership was likely more than enough to boost the battery to a level that would require a few days before the the techs could see your issue.

As far as why it behaves at the dealership? Could be a lot of reasons. One being fob proximity. My Prius unlocked when it sensed the fob. IOW, didn't have to push a button to unlock. So every time I walked by the Prius with fob in pocket, it would "wake" the car up. Increasing its 12 volt drain. This is a likely situation in your house but not so much at the dealer.

But what has been very established is the algorithm is not sufficient to maintain the 12 volt in "any" kind of slightly unusual conditions and since your car was not made to sit... its lack of exercise is a problem.

Combine that will cold weather and its effects on lead acid and it is highly recommended you take additional steps to maintain the battery.

FYI; the algorithm has gotten better by my initial observations but I still see voltage as low as 12.15 volts. Still enough to start the car but the buffer is nowhere near being in my comfort zone.
 
nlspace said:
+1 with Gerry

Stuck relay (welded contacts) is most likely cause of a 0.2A drain.
Click to expand...
In my case, the relay was mechanically sticking--the contacts were fine. It was intermittent because it would drop out most of the time, but stick once in a while. The contacts of those little relays can handle way more current than their normal load so contact welding is not usually an issue.
 
DaveinOlyWA said:
leaferone said:
For the past few months, I've been having a phantom drain on my 12v battery in my 2011 Nissan Leaf. It goes dead after just under a week of sitting idle. I've monitored the voltage and it steadily drops over time (going from about 12.50 to about 12.20 in a day, for example). A current meter consistently indicates that there's a 0.19amp draw. The TCU is unplugged, and pulling fuses from under the fuse box under the hood does not help (though I have only tried the regular fuses and also haven't touched the passenger compartment fuse box).

Here's the weird thing. This always happens, and has for months. But when I took it to a Nissan dealer, it sat there for nearly a week and they claim it only lost a trivial amount of voltage (0.02v) in that time. I am just baffled by this. Why would it consistently drain at home, but not at a dealer? I can't think of a reason why they would lie about it (they're turning down work to fix the problem).

Any ideas for what could be causing this or why it might behave differently based on location?

Thanks in advance!
Click to expand...

Ok the power usage is not consistent. You have several events that will increase the draw. Your 12 volt is charged by the LEAF regularly. Problem with this is the battery is never fully charged and runs on an algorithm which we can only guess was determined based on "normal" usage of the car. Your driving to the dealership was likely more than enough to boost the battery to a level that would require a few days before the the techs could see your issue.

As far as why it behaves at the dealership? Could be a lot of reasons. One being fob proximity. My Prius unlocked when it sensed the fob. IOW, didn't have to push a button to unlock. So every time I walked by the Prius with fob in pocket, it would "wake" the car up. Increasing its 12 volt drain. This is a likely situation in your house but not so much at the dealer.

But what has been very established is the algorithm is not sufficient to maintain the 12 volt in "any" kind of slightly unusual conditions and since your car was not made to sit... its lack of exercise is a problem.

Combine that will cold weather and its effects on lead acid and it is highly recommended you take additional steps to maintain the battery.

FYI; the algorithm has gotten better by my initial observations but I still see voltage as low as 12.15 volts. Still enough to start the car but the buffer is nowhere near being in my comfort zone.
Click to expand...

I agree that the algorithm is not sufficient to maintain a full charge for a Leaf not used on a regular basis.

Five minutes charging by 120 hours on a 2012.

Four minutes each day for a 2015, but on 2015, charging interrupted if current more that 1.5 A after start of automatic charging.

2012:
https://drive.google.com/file/d/1oybctQLmmip_KoNO6gAaL_k_LZh4IvJc/view?usp=sharing

2015:
https://drive.google.com/file/d/1M8z8LEly5nTl8cTymo1bEN5TBwa3N-jS/view?usp=sharing
 
LeftieBiker said:
There is no need to remove anything. You don't want to use the Negative terminal on the 12 volt battery, though: use the bolt on the upper right side of the PDM stack - aka the thing that looks like an engine head and valve cover. I will post a picture with it circled if you need one. EDIT: there are two candidates on your car, as shown.
Click to expand...
Thank you for sharing that picture. Unfortunately, my Leaf looks a bit different from your under the hood. Any chance you could point me to the right spot on the configuration that is in my type of Leaf configuration? Here's a picture that looks like mine:

https://s35.wheelsage.org/picture/n/nissan/leaf/nissan_leaf_44.jpg



GerryAZ said:
I had an intermittent 12V battery drain on my 2011 that was caused by one of the little relays in the box up high under the hood on the passenger (right) side near the firewall failing to drop out when the car was turned off. It took me a while to find it, but the power draw you are describing is about the amount I had so it would discharge the battery if the car sat for too long. Try tapping on those relays one at a time to see if your current draw goes away. Replacing the little relay fixed my problem until the car met its demise. The relay should have been covered by warranty, but only if I could reproduce the problem at the dealer so I just bought a new relay and plugged it in.
Click to expand...
Thank you for that info! I'm definitely going to need to look at those relays! Could you confirm that I'd be looking in the right place if I examine the relays shown in the picture in this thread?

https://www.mynissanleaf.com/viewtopic.php?t=21647

Any other places I should check relays?
 
Thank you for sharing that picture. Unfortunately, my Leaf looks a bit different from your under the hood. Any chance you could point me to the right spot on the configuration that is in my type of Leaf configuration? Here's a picture that looks like mine:

https://s35.wheelsage.org/picture/n/nis ... eaf_44.jpg
Click to expand...

Never trust google! Your stack has three bolts in the same locations, facing the 12 volt battery. Just choose the one that looks least important, but still goes into metal.

rTK60gn.jpg
 
My last..."few" LEAFs were marked + and - but still on the side of the "valve cover" looking thing. Actually don't remember if my 2011 or 2013 had it but I have a pix of my 2016 that shows it.
 
I am confirming that one of the little blue relays in the image you attached from the other thread was mechanically sticking (intermittently) on my 2011. Replacing the defective relay cured my problem. Your car may be parked at a different angle or in different ambient conditions when you take it to the dealer so the relay may not stick while parked there.

There is a lot of discussion in this thread about external chargers/maintainers, but I am guessing that you have had no problem until recently so your issue is the 0.2 ampere draw. While there is nothing wrong with using an external charger, that will just hide the continuous current draw so you need to correct the real issue by eliminating that current draw while parked. To troubleshoot, I would verify the current is there with your clamp-on meter and then tap on the little blue relays one at a time while watching the meter. If the current does not go away by just tapping on the relays, then try removing one relay at a time while watching the meter.
 
I finally got a chance to pull the fuses from the passenger compartment fuse box. No change whatsoever. Still has a 0.19A draw.

And thank you, LeftieBiker, for the picture to help me find the right spot for grounding. That was very helpful.



GerryAZ said:
To troubleshoot, I would verify the current is there with your clamp-on meter and then tap on the little blue relays one at a time while watching the meter. If the current does not go away by just tapping on the relays, then try removing one relay at a time while watching the meter.
Click to expand...
I tried tapping on the relays and that did not do anything. My next step was going to be removing the relays to see if that helped, but... I'm not sure how to safely remove the relays without damaging them. Is the a catch that has to be held back to remove them? I don't want to use brute force and end up breaking them myself. I tried to find a video, but I couldn't find any specific for the Leaf and the others didn't seem to be the same. Sorry for the dumb question!
 

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