How's your 12v battery health?

[GlennD]

I purchased a cigarette lighter voltmeter.

On my 2013 Leaf on accessory it would read in the very high 11's or very low 12's. When the car was turned on the inverter would read around 13.8V

Using the same voltmeter on my B Class before turn on the voltage reads around 12.5V. When the car is on and the inverter kicks in it reads around 14.8V.

To me that says that Nissan never allows the battery to fully charge. Tesla might be over charging the battery but I will see what develops The car has a warranty 2 years longer than my lease.

 

[DaveInAvl]

Here's another data point:

2014 SL, 11.5 months, 7200 miles, parked outside in Asheville NC.
After sitting overnight on its own: 12.48V.

I'm still sticking to the idea that any voltage measurements need to be done after fully charging the battery and the disconnecting it to let it rest. Then after some time at rest measuring the voltage.

I interpreted the thread title as asking how well folks' LEAFs were keeping their 12v batteries charged. That was the question I answered

 

[QueenBee]

Here's another data point:

2014 SL, 11.5 months, 7200 miles, parked outside in Asheville NC.
After sitting overnight on its own: 12.48V.

I'm still sticking to the idea that any voltage measurements need to be done after fully charging the battery and the disconnecting it to let it rest. Then after some time at rest measuring the voltage.

I interpreted the thread title as asking how well folks' LEAFs were keeping their 12v batteries charged. That was the question I answered

And my theory is the same. You can't tell the SOC by measuring the voltage if you have not let th battery rest.

 

[69800]

Has anybody ever measured the parasitic load on the 12v battery with the leaf just sitting. I used to have a nice Fluke amp meter that would measure millivolt amps but I don't anymore. The clamp on type amp meter are not sensitive enough for a good reading. I believe there is probably a 50 to 100 millivolt draw from the computer at all times which may be responsible for the resting battery voltage slowly dropping when the car is left parked for many days.

I found the answer.....about 20Mv

 

[GlennD]

Minor nit. Current is in Amps or miliamps ( Ma). Voltage is in volts or milivolts (Mv).

 

[Nubo]

Has anybody ever measured the parasitic load on the 12v battery with the leaf just sitting. I used to have a nice Fluke amp meter that would measure millivolt amps but I don't anymore. The clamp on type amp meter are not sensitive enough for a good reading. I believe there is probably a 50 to 100 millivolt draw from the computer at all times which may be responsible for the resting battery voltage slowly dropping when the car is left parked for many days.

I found the answer.....about 20Mv

It varies. When plugged in it tends to be higher, and also "wakes up" intermittently with much higher draws up to a full ampere. The 12 is topped off if the main pack is being charged, but if fully charged and plugged-in this doesn't happen; the 12V drains. This is why it's recommended to leave the car unplugged if not driving it for an extended period and in general it's best to unplug once the car has finished charging. E.g. don't let it sit plugged-in over a weekend if it was already fully charged by Saturday morning.

 

[wwhitney]

Minor nit. Current is in Amps or miliamps ( Ma). Voltage is in volts or milivolts (Mv).

Second nit: M is for mega (10^6), m is for milli (10^-3), and the single letter symbol for amps, volts, and watts are all capitalized (unlike the full words). So that's mA, mV, and mW.

Cheers, Wayne

 

[desiv]

I didn't notice it in this thread (if I missed it, mea culpa), but do you think the voltage readout for the 12V in Leaf Spy Pro (bottom left of the screen) is an accurate representation for 12V battery health?

Just wondering...

desiv

 

[QueenBee]

The 12 is topped off if the main pack is being charged, but if fully charged and plugged-in this doesn't happen; the 12V drains. This is why it's recommended to leave the car unplugged if not driving it for an extended period and in general it's best to unplug once the car has finished charging. E.g. don't let it sit plugged-in over a weekend if it was already fully charged by Saturday morning.

There is also a timer component where the car will connect the main battery for the sole purpose of charging the 12 volt battery. There are other threads which go into detail of how this works and interacts with being plugged in vs not, etc.

 

[baustin]

I ran into this today. I drove it Monday and put it on the charger that evening. I didn't go anywhere Tuesday and just left it plugged in. When I tried to remotely turn on the AC this afternoon, I got a message that it could not respond due to poor cell reception. When I went to leave, the battery was low enough that the door would not unlock. I had to use my key to open it and a portable battery jump unit to get it started. My trip and other meters were also all reset, but not the clock or radio station.

I've had the car 16 days, and left it plugged in like this before. This is the first real problem I've had, since I bought it (the other was low pressure in one of the new tires the seller put on it).

 

[TimLee]

I didn't notice it in this thread (if I missed it, mea culpa), but do you think the voltage readout for the 12V in Leaf Spy Pro (bottom left of the screen) is an accurate representation for 12V battery health?

Just wondering...

desiv

No.
Quoting from one of the best experts participating on MNL from this link:
http://www.mynissanleaf.com/viewtopic.php?f=30&t=12872&p=294278&hilit=battery+test#p294278" onclick="window.open(this.href);return false;

...To properly test the 12V, you cannot use a voltmeter. You must use a transconductance analyzer or at least a decent load tester. Most dealers have a midtronics tester that uses the transconductance method. I'd ask to see that test and verify they aren't just reading voltage.
...
-Phil

Plus, for LEAF Spy Pro to read the 12V battery voltage, the LEAF has to be on or charging, so mostly you are reading the voltage output from the DC to DC converter.
Completely meaningless.

The only time it does tell you something useful is if you have put the LEAF in ON mode, either single Power button push, or the LEAF was charging and when charging completed the LEAF then was in ON mode with no DC to DC available.

If that happens you can see the 12V battery drain and can monitor the rapidly declining voltage.

 

[RegGuheert]

Has anybody ever measured the parasitic load on the 12v battery with the leaf just sitting.

I have. The bottom line is that my 2011 LEAF draws approximately 25mA average when unplugged and not charging (and after sitting for some time so that all of the larger loads have had a chance to switch off). When the ELM327 is plugged in, it draws about 175mA, or 7X as much!

 

[69800]

I purchased a cigarette lighter voltmeter.

On my 2013 Leaf on accessory it would read in the very high 11's or very low 12's. When the car was turned on the inverter would read around 13.8V

Using the same voltmeter on my B Class before turn on the voltage reads around 12.5V. When the car is on and the inverter kicks in it reads around 14.8V.

To me that says that Nissan never allows the battery to fully charge. Tesla might be over charging the battery but I will see what develops The car has a warranty 2 years longer than my lease.

If you leave your voltmeter in all day every day you will see that most of the time your inverter will only remain at the higher voltage for less than 5 minutes and then drop to float voltage of 13.1 volts for the remainder of the drive.

 

[LeftieBiker]

This seems like a good place to ask: exactly how do I top off the distilled water in the 12 volt battery? I've done it with motorcycle batteries often enough. It looks like I have to remove the top of the battery hold-down to do it, true? Is it easy to see the levels for each cell from the top?

 

[epirali]

Has anybody ever measured the parasitic load on the 12v battery with the leaf just sitting.

I have. The bottom line is that my 2011 LEAF draws approximately 25mA average when unplugged and not charging (and after sitting for some time so that all of the larger loads have had a chance to switch off). When the ELM327 is plugged in, it draws about 175mA, or 7X as much!

Plugged in or plugged in AND on?

 

[RegGuheert]

This seems like a good place to ask: exactly how do I top off the distilled water in the 12 volt battery? I've done it with motorcycle batteries often enough. It looks like I have to remove the top of the battery hold-down to do it, true? Is it easy to see the levels for each cell from the top?

With the MY2011/2012, you don't even need to remove the covers to check the water level since the case is translucent...and you can remove the caps to fill without taking anything else off.

But it appears you have a MY2013, so I don't know how to open it. In any case, I would recommend that you simply ignore the water level. The way the LEAF charges (or rather, DOESN'T charge) the 12V battery, it uses almost no water. Our LEAF's 12V battery has lost less than about 1/8" of water (down to the FULL line) in over three years and I have another 3/4" to go before I need to add any. At this rate, I won't have to fill it for another 18 years!

Has anybody ever measured the parasitic load on the 12v battery with the leaf just sitting.

I have. The bottom line is that my 2011 LEAF draws approximately 25mA average when unplugged and not charging (and after sitting for some time so that all of the larger loads have had a chance to switch off). When the ELM327 is plugged in, it draws about 175mA, or 7X as much!

Plugged in or plugged in AND on?

Unplugged and off. (What was plugged in in the second reading was the ELM327 into the diagnostic port.)

 

[Levenkay]

The way the LEAF charges (or rather, DOESN'T charge) the 12V battery, it uses almost no water. Our LEAF's 12V battery has lost less than about 1/8" of water (down to the FULL line) in over three years and I have another 3/4" to go before I need to add any.

In mulling over the LEAF's 12V system, I've climbed up on a low pile of shaky facts and often-heard lore, and leapt to a conclusion that I'd be kind of curious to get the forum's reaction to.

I've gathered that the acid electrolyte in charged lead-acid batteries degrades the lead plates in ways that are seemingly external to the electrical current/ion flow, and that by "overcharging" the cells (continuing to push current into them up past the cell-voltage-times-number-of-cells level of 12V), this plate degradation can be reversed. Kind of like electrochemically refining metals, I imagine. Anyway, it seems to me that there's a fair bit effort required to keep undoing the Pb-H+ battery's background degradation, which translates into a continual power requirement that the LEAF designers didn't want to pay. Of the tradeoffs I can think of (pick a better 12V battery chemistry, try to take more advantage of shore/regen power, gritting teeth and burning the joules), it seems that Nissan went for just cutting the maintenance power to the bone, accepting an inadequately maintained battery, and hoping that a lightly loaded battery that yields a service life as if it's cranking dump-truck starters day in/out, won't disappoint LEAF owners too badly.

How far off-base is all this?

 

[RegGuheert]

Of the tradeoffs I can think of (pick a better 12V battery chemistry, try to take more advantage of shore/regen power, gritting teeth and burning the joules), it seems that Nissan went for just cutting the maintenance power to the bone, accepting an inadequately maintained battery, and hoping that a lightly loaded battery that yields a service life as if it's cranking dump-truck starters day in/out, won't disappoint LEAF owners too badly.

It may have been a conscious decision, but I guess we will never know. Another benefit of their approach is the minimized quantity of sulfuric acid released under the hood, so very little chance of corrosion.

Still, I think letting the charge voltage stay at 14.5V during one complete charge session each week (no other changes) would be a massive improvement. It would result in no change in driving range and only minimal additional amounts of electricity drawn from the wall while greatly reducing the number of 12V batteries which need to be recycled due to charger abuse.

I guess Nissan dealers would HATE such a change...

 

[LeftieBiker]

But it appears you have a MY2013, so I don't know how to open it. In any case, I would recommend that you simply ignore the water level. The way the LEAF charges (or rather, DOESN'T charge) the 12V battery, it uses almost no water. Our LEAF's 12V battery has lost less than about 1/8" of water (down to the FULL line) in over three years and I have another 3/4" to go before I need to add any. At this rate, I won't have to fill it for another 18 years!

In my case I think I need to check it. I use a battery maintainer, and the car is connected to it at least 60% of the time. So, anyone know the details for a 2013?

 

[RegGuheert]

The way the LEAF charges (or rather, DOESN'T charge) the 12V battery, it uses almost no water. Our LEAF's 12V battery has lost less than about 1/8" of water (down to the FULL line) in over three years and I have another 3/4" to go before I need to add any. At this rate, I won't have to fill it for another 18 years!

We have had our LEAF for just over seven years now and since the car was assembled in June of 2011 the 12V battery was likely manufactured about eight years ago. Since it has been a few years since I have posted about our 12V battery, I thought it might be a good time to give a quick status update.

Ever since September 2012 when I discovered that our LEAF tended to allow the 12V battery to drop down below about 12.4V when resting, I have occasionally fully charged it with a BatteryMinder 1500 to ensure that it is both fully charged and desulfated. As a result, the 12V battery seems to be in excellent health. It often shows over 12.7V for up to a day after being shut off (and the LEAF is not plugged in). The water level has now dropped to about the halfway point between the "Upper Level" and "Lower Level" marks on the battery, with each cell having virtually the same level.

I suppose it will be another seven years or so before I need to add water to this battery.