12v Battery

EVger said:

I am planning to leave my Leaf in the garage for four to five months. I would appreciate some information:
Can I just leave the car without the 12v likely to go dead? (Does the electrical system go to sleep and/or does the 12v draw a charge from the traction battery, but not so much as to dangerously drain the traction battery over several months?)
Should I leave the EVSE plugged in to charge the traction battery? (Which would probably maintain a 100% SOC on the traction battery for a considerable time.)
Should I use a battery tender for the 12v battery? If so, what is the most convenient way to make the connection? (Just use the alligator clips? On the negative terminal or the car frame?)
Thanks for your help.

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Based on the admonishment I the manual to not leave the LEAF main battery at high charge for extended periods of time, I left my 2016 SV at 60%. I also left it unplugged as that is one less thing subjected to lightning strikes and brown outs on the grid. I did have a Battery Minder desulfating maintainer connected to the 12V battery (yes, that was connected to the grid).

Upon return six months later, the main battery was at 59% and the same capacity as before I left. Always good to check the 12V battery electrolyte levels and top up with distilled water if necessary. First "battery report" from the dealer gave five stars across the board. Interestingly the "extended time at high state of charge" seems to be removed from the report.

I believe the 2015 and newer models top up the 12V battery every 24 hours for five minutes if not driven or charged. I've seen mine do this. Perhaps the battery maintainer was overkill. Nevertheless, it all worked out for my Seattle to Phoenix snowbirding. Granted, my LEAF was stored in practically ideal temperatures.

Interestingly the "extended time at high state of charge" seems to be removed from the report.

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Presumably because they no longer give the option to charge to 80%.

EVger,

If you leave the car at 60% to 70% state of charge and not plugged in, it will be fine in moderate or warm temperatures. In extremely cold temperatures, higher initial charge would be OK since it might need to run the battery heater down near 0 degrees F. Make sure there is nothing plugged in to the OBDII port, nothing is left on, and all doors are closed (and locked, if desired). I have parked my 2011 and 2015 for up to 3 weeks at my office or the airport numerous times without issue (except the one time I left the Bluetooth adapter plugged in to the OBDII port on the 2011 and came back to a dead 12-volt battery after only 6 days). The SOC of the traction battery is essentially the same after 3 weeks as when it was parked. According to the manual, the 2011 would charge the 12-volt battery for 5 minutes every 5 days. The manual says the 2015 will charge the 12-volt battery periodically as necessary so I think it monitors the voltage instead of just charging every 5 days. In either case, both cars keep (kept) the 12-volt battery adequately charged.

A "battery tender" is OK if you are comfortable leaving something plugged in unattended for that long, but I personally do not trust them so I either periodically charge batteries on other vehicles or disconnect them to prevent discharge. I like the fact that I don't need to do anything with the LEAF except make sure it is parked at half charge.

Also, the telematics unit and CarWings (EV Connect) go dormant after the car has been parked for 2 weeks so do not be alarmed when you cannot check status remotely (SV and SL models).

EVger said:

I am planning to leave my Leaf in the garage for four to five months. I would appreciate some information:
Can I just leave the car without the 12v likely to go dead? (Does the electrical system go to sleep and/or does the 12v draw a charge from the traction battery, but not so much as to dangerously drain the traction battery over several months?)
Should I leave the EVSE plugged in to charge the traction battery? (Which would probably maintain a 100% SOC on the traction battery for a considerable time.)
Should I use a battery tender for the 12v battery? If so, what is the most convenient way to make the connection? (Just use the alligator clips? On the negative terminal or the car frame?)
Thanks for your help.

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My experience is with a 2012 Leaf with the original 12V battery. After joining this forum over a year ago, I began to read about isolated incidents of completely dead Leafs due to failed batteries. It got me more than a little worried. After a series of "tests" I concluded that for my vehicle, the "charging" system was certainly not optimum (never truly "floated" nor "equalized" the FLA battery). My best (test) guess was that the SOC was maintained at 70% or less almost all the time - marginal for sulfation prevention. My solution has been to use one of the Northern Tool $25 desulfating trickle charger if I do not use the Leaf for more than a week or so, equalize the battery every couple of months, and keep my amazing 12 ahr lithium battery "jump starter" in the trunk ( I have one to start my 6500 watt generator).

If I were to leave my Leaf for several months, I'd first fully charge the battery with a conventional 15+ amp charger, then put the trickle charger on it - if nothing else but to actually float it and possibly even desulfate it (although I have no proof that they actually work!). My battery has never failed me (yet).

I had to replace the 12V battery in the 2011 SLe Leaf, 6 years without 2 weeks. I bought the Costco battery for $73.

I was abroad for 3 weeks and my wife forgot to use the car or power it up. She also looked for something inside for an hour and left the light on. The battery was dead when I came back. I charged it and it worked for a week with daily use. Over the weekend, not being used, it died again.

The car is parked outside during the day 11 hours, 4 days a week, the little solar panel likely helped extending the battery life. In garage overnight. Short trips over the 3 day weekends.

I've been trying for 2 years to get a Nissan dealership to add distilled water to my 12 volt battery. Usually they just don't do it, but today they told me that the car has a maintenance free battery. I guess I'll have to do it myself.

LeftieBiker said:

Even a Battery Tender Jr, with a whopping 0.75 amps, will keep a Leaf battery charged if given long enough. I'm using one now, and it usually only takes an hour or two to top off my battery.

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Can this, while being connected to battery positive and Chassis ground be used at the same time as Traction battery charging or will it screw something up? IE: Do they need to be charged separately?

I've actually hooked up a 15 amp battery charger (as well as the "tender") while the Leaf is "started" - just to see the effects of battery voltage and current flow with LeafSpy - no apparent affect on any operations.

Lambtron said:

LeftieBiker said:

Even a Battery Tender Jr, with a whopping 0.75 amps, will keep a Leaf battery charged if given long enough. I'm using one now, and it usually only takes an hour or two to top off my battery.

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Can this, while being connected to battery positive and Chassis ground be used at the same time as Traction battery charging or will it screw something up? IE: Do they need to be charged separately?

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I charge them together all the time. No problem.

LeftieBiker said:

Lambtron said:

LeftieBiker said:

Even a Battery Tender Jr, with a whopping 0.75 amps, will keep a Leaf battery charged if given long enough. I'm using one now, and it usually only takes an hour or two to top off my battery.

Click to expand...

Can this, while being connected to battery positive and Chassis ground be used at the same time as Traction battery charging or will it screw something up? IE: Do they need to be charged separately?

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I charge them together all the time. No problem.

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Hopefully whatever charger/maintainer's is used, that the output 'floats' (isolated) relative to the 110V line.

lorenfb said:

LeftieBiker said:

Lambtron said:

Can this, while being connected to battery positive and Chassis ground be used at the same time as Traction battery charging or will it screw something up? IE: Do they need to be charged separately?

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I charge them together all the time. No problem.

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Hopefully whatever charger/maintainer's is used, that the output 'floats' (isolated) relative to the 110V line.

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Thanks all, Until now I hadn't needed external charging of the 12 volt, However I
Woke up Thursday night to the heavy smell of battery acid in the garage. The 12v was boiling and the case swollen and at 197*. Battery was an O'reilly extreme @ 2 yrs old this week. They replaced it under full warranty. The car is driven 30 miles every day and no codes are present, so I'm assuming it may have had a sulfated a cell.

That sounds a lot more like overcharging than a sulfated cell.

LeftieBiker said:

That sounds a lot more like overcharging than a sulfated cell.

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Yep. Most likely due to a shorted cell: the other five cells then get overcharged.

How powerful was this charger, anyway? It's best to use something with a very low current limit, like 1.5 A.

RegGuheert said:

LeftieBiker said:

That sounds a lot more like overcharging than a sulfated cell.

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Yep. Most likely due to a shorted cell: the other five cells then get overcharged.

How powerful was this charger, anyway? It's best to use something with a very low current limit, like 1.5 A.

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It was never on a charger.It was all leaf. I'm considering it now to prevent future events if this was due to sulphation. I ran the leafspy when it happened, The 12 volt battery read 10 volts and all cockpit gauges seemed fine. The only code was something in reference to the Brake booster voltage. (Probably from the low batt Voltage. I pulled the battery out and took it outside fearing an explosion. I then hosed it down trying to cool it but it seemed to just keep getting hotter. On placing the new one in service we monitored the charge current and voltages and after the initial 14 volts for 15 second charge the car settled at 12.96 @1.36 amps. I drove the car another fifty miles while monitoring leafspy,no changes. By the way, Leafspy was within .1v reading of my Fluke scopemeter. I am hoping it was just the battery.

Reg and I are likely still right. One cell shorted out, and the car tried to charge the battery to the full 6 cell voltage, eventually causing the electrolyte to boil. It's ironic, considering how little the cars usually charge that battery.

LeftieBiker said:

Reg and I are likely still right. One cell shorted out, and the car tried to charge the battery to the full 6 cell voltage, eventually causing the electrolyte to boil. It's ironic, considering how little the cars usually charge that battery.

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Well in any case, I installed the charge quikconnect cable for my .75A tender / maintainer in the charge port door in case I decide to use it.

Lambtron said:

I am hoping it was just the battery.

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That's what it sounds like to me.

Be sure to thoroughly hose off the motor compartment in the LEAF in case any sulfuric acid (either in liquid or gaseous form) got on any of the surfaces in there. That stuff will eat through just about anything!

Lambtron said:

LeftieBiker said:

Reg and I are likely still right. One cell shorted out, and the car tried to charge the battery to the full 6 cell voltage, eventually causing the electrolyte to boil. It's ironic, considering how little the cars usually charge that battery.

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Well in any case, I installed the charge quikconnect cable for my .75A tender / maintainer in the charge port door in case I decide to use it.

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That's well worth the extra installation work because of the resulting ease of use.

Given all the hysteria on the Leaf's 12V battery, you'd think there would be answer to this one:

LeftieBiker wrote:
The problem with the above is that the car makes no effort to FULLY charge the 12 volt battery even under optimum conditions. It either charges for a fixed amount of time or to a too-low voltage. As a result the 12 volt battery in a pre 2014 will be chronically undercharged unless you use an external charger once or twice a week...

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lorenfb wrote:
So the 2014+ Leafs have an improved charging algorithm? Haven't heard of this before, is it posted somewhere?
If so, are the pre-2014 Leaf's capable of having the ECU, e.g. the BMS, responsible for 12 battery charging re-flashed?
My 2013 has never had any 12 volt battery issues and I don't use a maintainer, although my SL with a PV cell
does supply about 50ma in moderate sunlight over the standby battery drain of about 30ma.

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Waiting.

lorenfb said:

Given all the hysteria on the Leaf's 12V battery, you'd think there would be answer to this one:

LeftieBiker wrote:
The problem with the above is that the car makes no effort to FULLY charge the 12 volt battery even under optimum conditions. It either charges for a fixed amount of time or to a too-low voltage. As a result the 12 volt battery in a pre 2014 will be chronically undercharged unless you use an external charger once or twice a week...

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lorenfb wrote:
So the 2014+ Leafs have an improved charging algorithm? Haven't heard of this before, is it posted somewhere?
If so, are the pre-2014 Leaf's capable of having the ECU, e.g. the BMS, responsible for 12 battery charging re-flashed?
My 2013 has never had any 12 volt battery issues and I don't use a maintainer, although my SL with a PV cell
does supply about 50ma in moderate sunlight over the standby battery drain of about 30ma.

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Waiting.

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It may depend upon usage patterns, but my 2011 kept its 12-volt battery charged and my 2015 has been keeping its original Nissan 12-volt battery charged. The original battery in the 2011 lasted at least as long as typical OEM batteries last in my climate. The original battery in the 2015 is still OK so it is doing better than normal. I NEVER used an external 12-volt charger on either LEAF, but did have to jump start 2011 and 2015 one time each (left Bluetooth unit plugged in to OBDII port of 2011 while parked for extended time and upgraded telematics unit kept systems awake on 2015 while parked for a few days).