Another 12v Battery Drain Issue (Not TCU Related)

[theblueleaf]

About a month ago, I got my 2011 Leaf back from the dealer. The main service they provided was installing a new 24kWh battery, but they also did some service bulletins work too, including disabling the TCU.

Since I got it back, I've been finding the 12v battery dead every few days. The first thing that I did was to: a) disable downloading/sharing and clear saved locations, as recommended (https://www.mynissanleaf.com/viewtopic.php?t=25722#p529077), and b) disconnect the TCU's power cable as recommended (https://www.mynissanleaf.com/viewtopic.php?t=25949#p528909). The battery still drained to empty even after these steps were done (and from a full charge), so I do not believe it is the TCU at fault, making this (as far as I know) not the same problem that others have dealt with).

I do not believe that the 12v battery is at fault (i.e, I think the 12v battery is in good health). Not only is the timing suspicious, but it has recharged three times and my charger has not flagged it as being in bad health AND it's not that old (manufactured in Oct. 2018). I tried using a multimeter to measure the amp pull and remove fuses one at a time, but I was not able to get it to work (when I tried to connect the multimeter in series, it registered 0.00 amps and I did not hear the tell-tale sounds from the car first getting power that I hear when I put the terminal on the post directly). I am a DIY person, but with limited electrical experience, so I was hesitant to mess around too much.

I am hesitant to take it back to the dealer because: a) anecdotal stories from others with 12v battery drains suggests low success rates in dealers fixing the problem, and b) it is basically an 8-hour commitment to get it to the dealer and back because of the distance to the nearest EV Nissan dealer. If I can fix this myself, I'd very much like to do so.

Currently I have cleared charge timers and also pulled the "audio" fuse (which powers the TCU, video screen, etc.) to see if the battery still drains. I'll wait a few days (checking the voltage periodically to monitor for drops) and see if that fixes the problem (and, if so, then try putting the fuse back to see if the charge timer was the problem). But in the meantime, is there anything I could/should do or try?

 

[gncndad]

WAG here, but...if your traction battery needed replacement, is it possible it was putting undue stress on the 12V battery you installed in Oct. 2018?

What type of replacement 12V battery did you install? Have you done an actual load test on the battery (detached from the car)?

 

[LeftieBiker]

Make sure that they used the correct pack and kit for your 2011 - with NO battery heater.

 

[theblueleaf]

Thanks for the responses!

WAG here, but...if your traction battery needed replacement, is it possible it was putting undue stress on the 12V battery you installed in Oct. 2018?

The traction battery was degraded to about 60-65% original capacity. Unless I'm missing something (and I very well might be), I wouldn't expect that alone to cause stress on the 12V. It's possible that there was more to it, but it's impossible to know given how little information they share from the tests they do on the traction batteries.

What type of replacement 12V battery did you install? Have you done an actual load test on the battery (detached from the car)?

It's a 51RPRM. It performed just fine for the 15 months between when I bought it and when this most recent service was performed. I have not done any tests on the 12V battery (other than the minimal indicators from the basic battery charger), but may do so before resorting to going back to the dealer just in case. Given the sudden onset of the problem and the timing with the service, even if it failed a test I'd consider it possible that the repeated draining to empty may have been a contributing factor, rather than the other way around.

Make sure that they used the correct pack and kit for your 2011 - with NO battery heater.

Interesting. I wasn't aware that there were different options/parts. Is there a way that I can determine what I got? I have the invoices with part numbers, but I'm not sure what I'm looking for. Could that even be an issue? The car hasn't been sitting in cold weather during this time frame (it's in a garage that stays above freezing this time of year). If this thread (https://mynissanleaf.com/viewtopic.php?t=11326) is correct, then this was well above the temperature range when a heater would even activate (which might not mean anything if the problem is that it stays on or something).

 

[LeftieBiker]

There have been charging system issues when the wrong pack (heated pack where there was no heater before) was installed. You can tell from the part number, but I don't have that info. It is here, somewhere...

 

[BrockWI]

My guess is the 12v sat dead during the swap and killed it. As I recently found out, the easiest thing to do is swap the 12v for a new one and charge it full. It's probably the least expensive you can do, short of, like you tried, to track down what is draining it.

 

[alozzy]

In case it is useful, on page 19 of the Nissan TSB linked below, there is a table containing replacement pack part numbers:

https://testing-public.carmd.com/Tsb/Download/126060/NTB14-059c

Based on that table:

• For a 2011 LEAF without the cold weather package, the HV pack part number is 295B0-3NF9E
• For a 2011 LEAF with the cold weather package, the HV pack part number is 295B0-9RB9D

Also from the article: "... Cold Weather Package vehicles can be identified by having heated steering wheel, heated front and rear seats, heated outside mirrors and rear HVAC duct ..."

So hopefully the work order or invoice shows the HV pack part number that was installed, allowing the OP to confirm that the correct pack part number was installed for his 2011 LEAF.

 

[LeftieBiker]

Thanks for the above.

 

[Turbotoshi69]

That's a hard problem to diagnose. I would negate the batery as it wouldn't really charge if it was bad, as i understand you drive around it's all well few days later u wantto drive the battery is basicly dead because something is drawing power. If the batery was bad, after u start driving and u stop, to start again, the batery wouldn't have enough power because when it's bad id oesn't really hold charge anymore.

 

[Lothsahn]

Just to jump in...

There's a problem if the car has a cold weather package and the battery does not. There is NO problem if the battery has the heater but the car does not expect it. I've heard that there are some 2011's with a cold weather package, but I've never seen one. Does your car have heated seats? If not, you don't have the cold weather package and this issue doesn't affect you. In short: a 2011 getting a 2012 pack (or a replacement pack with the heater hardware) should not cause any problems. https://www.mynissanleaf.com/viewtopic.php?f=30&t=30963&p=580244&hilit=battery+swap+drain#p580244

Do you see the 3rd blue light on the dashboard (the 3 lights that come on when you charge the car) come on intermittently or frequently when the car is off? This can indicate the car is topping off the 12V battery.

I suspect the 12V has gone bad, like others in the forum. I had a 12V battery that would hold a nice charge up to like 12.7V, but it'd just randomly die. Since it appeared to be the original OEM battery (and this was 6 months ago), I figured 8 years was pretty good on a Leaf 12V and replaced it with an Optima Yellowtop AGM. While the battery would rest at 12.7V using a multi-meter, it failed the load test which identified it as a bad battery. I have had zero 12V problems since.

If you want to troubleshoot the car, I'd attach an ammeter on the terminals of the battery to see what the power drain is when the car is off.

The other sad thing is that, depending on how many times this has drained your 12V battery, it may be sulfated now even if it was fine before. 12V batteries can only go flat a few times before they're toast.

 

[theblueleaf]

Once again, thanks for all the replies.

• For a 2011 LEAF without the cold weather package, the HV pack part number is 295B0-3NF9E
• For a 2011 LEAF with the cold weather package, the HV pack part number is 295B0-9RB9D

There's a problem if the car has a cold weather package and the battery does not. There is NO problem if the battery has the heater but the car does not expect it. I've heard that there are some 2011's with a cold weather package, but I've never seen one. Does your car have heated seats? If not, you don't have the cold weather package and this issue doesn't affect you.

My car does not have the cold weather package, so it sounds like this could not affect me. I also checked the invoice and confirmed using the above part numbers that my car correctly received the battery for a Leaf without the cold weather package.

Do you see the 3rd blue light on the dashboard (the 3 lights that come on when you charge the car) come on intermittently or frequently when the car is off? This can indicate the car is topping off the 12V battery.

I have not noticed that. Not before this issue and not since. But my car is in the garage, so the odds of me noticing it might be low anyway. I don't think it is happening, but I can't rule it out entirely.

If you want to troubleshoot the car, I'd attach an ammeter on the terminals of the battery to see what the power drain is when the car is off.

I've tried to attach my multimeter (on amp measuring mode) in series with the battery, but have not had any luck getting a reading (I don't think energy is flowing when I attach in series). Not sure if I'm doing something wrong or if my budget multimeter is not up to the task.

I suspect the 12V has gone bad, like others in the forum. I had a 12V battery that would hold a nice charge up to like 12.7V, but it'd just randomly die. Since it appeared to be the original OEM battery (and this was 6 months ago), I figured 8 years was pretty good on a Leaf 12V and replaced it with an Optima Yellowtop AGM. While the battery would rest at 12.7V using a multi-meter, it failed the load test which identified it as a bad battery. I have had zero 12V problems since.

If the 12V battery continues to drain now that I've disabled the charge timer and pulled the audio fuse, testing the 12V battery will be my next step. But my fear is that even if it is bad that might be because of this problem rather than the cause of it. I'll get a new 12V and see what happens if necessary. The OEM battery worked for 7+ years, so it would be a real surprise (but not impossible, of course) if this one lasted just a little over 1 year. Should still be under warranty.

 

[lorenfb]

If you want to troubleshoot the car, I'd attach an ammeter on the terminals of the battery to see what the power drain is when the car is off.

I've tried to attach my multimeter (on amp measuring mode) in series with the battery, but have not had any luck getting a reading (I don't think energy is flowing when I attach in series). Not sure if I'm doing something wrong or if my budget multimeter is not up to the task.

1. You may have a damaged amp-meter, or a bad meter fuse, the result of disconnecting either of the battery terminals and then
attaching the amp meter in series. This typically blows the meter fuse or damages the meter because of the high startup current
demand of the modules in the vehicle.
2. The proper way to check for standby current is to make sure the vehicle has entered its sleep mode. Then attach one meter
lead to the vehicle's chassis terminal lug. Next the other meter lead is touched to the center of the negative battery post,
followed by the removal of the negative battery clamp without disturbing the meter lead on that post. This avoids the high
current inrush when a battery is initially connected after having been fully disconnected.
3. The best method is to use a clamp-on amp-meter, and not the in-series type.

 

[LeftieBiker]

As already noted, the replacement 12 volt battery may have gotten fully discharged during the battery swap, and thus been damaged. It's not hard to ruin a perfectly good 12 volt battery quickly.

 

[theblueleaf]

I took the 12V battery in for a full load test. It passed no problem. I'm going to keep it disconnected when not in use to prevent damage from draining it.

The mystery drain has continued even with the audio fuse removed, so I am out of theories and running out of options. I could get a clamp-on amp-meter to troubleshoot some more (thanks, laurenfb, for the suggestion!), but I'm leaning more towards taking it back to the dealer at this point. I think I'll call Nissan's EV hotline and see if they have any guesses, and if not try the dealer next.

 

[goldbrick]

Another option besides the clamp-on ammeter is to check the voltage drop across each fuse. If you have a good set of multi-meter probes with long, sharp tips, there are usually a couple of small holes accessible on the tops of the fuses that can be probed while the fuse in place. Set your meter to the mV scale and it should be possible to determine which fuse is conducting the excess current. There are probably tables on-line to show the expected values or how to translate between mV and current based on fuse size, etc but if it is draining the battery in a few days the current is probably high enough that it would stand out readily.

 

[theblueleaf]

The dealer diagnosed the problem as a drain from the Body Control Module. They swear it is not related to the 24kWh battery being replaced and the timing is just coincidental. Apparently it will be an expensive fix and a new BCM is not going to be available until late-summer. Not thrilled, but the alternative appears to be keeping it on a battery tender whenever it's parked, which I'm not happy about either. I've decided to go ahead with getting a new BCM and keeping my fingers crossed that nothing else goes wrong.

Thanks again to everyone who offered advice!

 

[LeftieBiker]

I'd get it in writing that the problem is the BCM, and that replacing it will end the drain. Dealerships tend to do this: they confidently announce that it's X expensive part, and when replacing it fails to make a difference ,they just shrug and tell you that it's Y expensive part. And then Z. After which it's back to A.

 

[lorenfb]

About a month ago, I got my 2011 Leaf back from the dealer. The main service they provided was installing a new 24kWh battery, but they also did some service bulletins work too, including disabling the TCU.

Since I got it back, I've been finding the 12v battery dead every few days.

It's highly likely that the Nissan dealer's service department damaged the BCM (battery control module) when they installed the new 24kWh battery,
e.g. initially forgot to connected a chassis ground wire. Consider discussing that with the dealer that did the installation.

 

[gncndad]

About a month ago, I got my 2011 Leaf back from the dealer. The main service they provided was installing a new 24kWh battery, but they also did some service bulletins work too, including disabling the TCU.

Since I got it back, I've been finding the 12v battery dead every few days.

It's highly likely that the Nissan dealer's service department damaged the BCM (battery control module) when they installed the new 24kWh battery,
e.g. initially forgot to connected a chassis ground wire. Consider discussing that with the dealer that did the installation.

Would there be any telltale signs that the install of the new 24kWh caused the BCM to fail? How can this be proven?

 

[lorenfb]

About a month ago, I got my 2011 Leaf back from the dealer. The main service they provided was installing a new 24kWh battery, but they also did some service bulletins work too, including disabling the TCU.

Since I got it back, I've been finding the 12v battery dead every few days.

It's highly likely that the Nissan dealer's service department damaged the BCM (battery control module) when they installed the new 24kWh battery,
e.g. initially forgot to connected a chassis ground wire. Consider discussing that with the dealer that did the installation.

Would there be any telltale signs that the install of the new 24kWh caused the BCM to fail? How can this be proven?

Like most problems that arise from careless mechanics, it's very difficult requiring emphasizing;
1. The vehicle had no battery drain before 24 kWh battery replacement.
2. The BCM is integral to the functioning of the 24 kWh battery, e.g. it has physical wiring connections too it.
3. The Nissan repair manual's procedure for replacing the 24 kWh battery and each step needs to be reviewed as related to the BCM.