12v Battery

arnis said:

13.1V is definitely charging voltage.

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No, 14.5V is a charging voltage. 13.1V is known as a float voltage. It should be used after a full charged is achieved. And 13.1V is a very low float voltage, too low for an AGM battery. High-quality battery chargers tend to use 13.5V for a float voltage.

arnis said:

Though it is way too low for occasional use.

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It's way too low for a car which needs to return the lost charge to the battery quickly.

arnis said:

Is it verified with multimeter?

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Fluke 77.

arnis said:

13.1V might be reported by LeafSpy but what about real voltage @terminals.

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LeafSpy readings are worthless, IMO.

arnis said:

I checked my 2014 Leaf with voltmeter and clamp-on DC ampmeter, it charges as it is written in the literature.

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Do you have some literature which tells you what voltage the LEAF uses to charge the 12V battery? If so, can you please point us at it.

arnis said:

Maybe you have deep cycle AGM battery?

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Yes, I'm talking about an AGM battery.

arnis said:

On vehicles I've never seen that kind of resting voltage.

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Once you look at this plot, then you can say you have seen such high resting voltages in an automotive AGM, in this case that voltage is seen even when loaded by the LEAF.

arnis said:

BMW uses AGM batteries for a decade already. Almost all start-stop vehicles use AGM type.

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That's fine, but BMW does not use a charging or float voltage of 13.1V with those batteries.

arnis said:

I bought a second hand AGM battery that was tortured by 5-series for 6 years. It has more than 55% life left.

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That's great! That doesn't mean an AGM is a good choice for a Nissan LEAF which "charges" at 13.1V.

arnis said:

Depending on how discharged battery is it can swallow up to 4Ah during that period.

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Agreed. Charging will occur quickly if the battery is at a low SOC. But that doesn't address the issue of letting the battery sit not fully charged, which leads to sulfation.

arnis said:

I will verify my observations in near future but I'm pretty sure 2014 Leaf does NOT have 12V battery problems.

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If it doesn't spend any more time at 14.5V than I have specified, then it has problems.

arnis said:

PS! AGM batteries do not sulfate faster than flooded.

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Sulfation of AGM batteries is a huge problem in PV applications.

arnis said:

Also their sulfation is not thick due to absorption mats inside.

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I'm sure that's true. That is why I am able to recover the capacity for badly-sulfated AGMs. But it may take many MONTHS to break down all the sulfate. That's O.K. since I am using them for emergency backup. Any desulfation I can achieve is like getting a free battery.

arnis said:

And lead acid batteries should not sulfate AT ALL if used properly.

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We can agree on that. But they need to be returned to a full state-of-charge frequently to prevent the lead sulfate from hardening.

I just left my Leaf for almost 3 weeks and came back to slightly lower SOC (obviously due to charging the 12v battery a few times) and no problems starting. Pretty much validated my decision to go Lithium a couple of years ago (not that it hasn't already saved me from another 12v battery in the Texas heat).

Stanton said:

I just left my Leaf for almost 3 weeks and came back to slightly lower SOC (obviously due to charging the 12v battery a few times) and no problems starting. Pretty much validated my decision to go Lithium a couple of years ago (not that it hasn't already saved me from another 12v battery in the Texas heat).

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I have never argued against the Li-ion replacement recommendation. It's just a very expensive solution. I can achieve the same result (and possibly longer life) by using a flooded lead-acid battery, a high-quality desulfating trickle charger and some of my time. I can certainly see going the route you did.

But AGMs have such a high voltage when fully charged that the sulfation issue which occurs in the LEAF is even worse with that chemistry.

I tried going the AGM route here and found it was a mixed bag on my ICE vehicles. Here in Tampa Bay many times your best off with the lowest amperage traditional wet 12 volt battery required for your car with fill caps and a large case that holds plenty of electrolyte so you will see 5 years or so of usage. Many times when they pack in a lot of cranking amps into a small battery case you will only see a year or so of service even with an AGM. Sealed maintenance free just means short lived battery around here.

An old timer who rebuilt wet batteries for years told me that in our heat the best value will be from a taller wet battery with fill caps and plenty of room for electrolyte all around the plates especially above and below. In my RV I put in a float charger that goes into a desulfate mode automatically based on time, temperature and charging history.

There is no such thing as universal charging voltage. What changes is charging rate. Voltage at the terminals changes according to battery internal resistance while charging,resistance of everything else that charges it and state of charge.
Old-school BMW used constantly 13,7-13,9 as normal "charging voltage" at normal temperatures. If battery is depleted (and not sulfated) it would absorb charge at 100A rate easily for many minutes.
New Leaf + LeafSpy: I observe voltage data in LeafSpy that is comparable with multimeter on the terminals. I've heard that with older model it was not calibrated correctly.

When I said "it charges" I meant that current is flowing in the direction of battery at acceptable rate. Also Leaf does compensate charging voltage (your 13.1V) according to outside temperature (sensor is on 12V current sensor).

There are different types of lead acid batteries and there are different types AGM batteries. Those that have thicker electrode sheets and those that have thinner (for cranking).
Also batteryuniversity and other random sites do mention there are different "100% charged" voltages for AGM batteries (manufacturer based like I understood).

Newer BMW-s do have very smart BMS. In addition to start-stop BMW implemented EfficientDynamics at the beginning of this decade. This clever system keeps AGM battery charged at around 80%. During hard acceleration generator is disengaged. System voltage drops to 12-12,5 according to electrical load. And while decelerating generator is not just engaged, voltage regulator is set to 15,4V for maximum current flow. This results in regen at 3,5kW rate. This is possible as AGM battery is constantly kept at 80% during cruising. And sulfation is not a problem at that SOC (applies to AGM only) as those batteries last for many years (about 300-400Mm, Megametre, 1000km)

Of course sulfation is a huge problem. It is the main problem for any deep discharge scenario battery

If it doesn't spend any more time at 14.5V than I have specified, then it has problems.

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I'm sure normal voltage I observe on BMW-s is enough, 13,7-13,9V (fluctuates due to temperature) to not let battery sulfate. Except that if it is drained during resting periods of 5 days. That is bad.

Random unverified data. I have OEM BMW battery available and it rests at 12.7V after a long week of float charge and a week of rest.


I will report back with 2014 Leaf voltages once I have some free time.

RegGuheert said:

a lot

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RockyNv said:

I tried going the AGM route here and found it was a mixed bag on my ICE vehicles. Here in Tampa Bay many times your best off with the lowest amperage traditional wet 12 volt battery required for your car with fill caps and a large case that holds plenty of electrolyte so you will see 5 years or so of usage. Many times when they pack in a lot of cranking amps into a small battery case you will only see a year or so of service even with an AGM. Sealed maintenance free just means short lived battery around here.

An old timer who rebuilt wet batteries for years told me that in our heat the best value will be from a taller wet battery with fill caps and plenty of room for electrolyte all around the plates especially above and below. In my RV I put in a float charger that goes into a desulfate mode automatically based on time, temperature and charging history.

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AGM battery is not always plug-and-play with ICE vehicle. AGM is very very afraid of boiling electrolyte. Float voltage is lower than on normal flooded battery. But electrolyte does not tend to evaporate during normal operation as fast as flooded battery, especially in hot climate.

AGM accepts charge faster but if it is full it is bad to charge it further (or keep at 13,8V) . Something similar with Li-ion battery.

I have been with cars for many years, and have never heard so much arguing over a darn 12 volt battery!! Let's get realistic...

First, with the standard Leaf 12v battery... Buy a $40 plug-in "Battery Tender" for your garage, and every few weeks, or every month connect it to the battery until the "green light" lights. That means that your battery is fully charged. The Battery Tender is computer controlled, and can be left connected to the car indefinitely. I have a Miata that I do not use regularly, and it is connected to the Battery tender year-round.

When your small stock battery bites the dust, measure the size of your battery tray (and its height), go to Costco, and buy the biggest 12v battery that fits... EASY PEEZY.. PS - using this method, I still have a 10 year old battery in great shape in my car.

PS- for those without a garage or an outlet, get a Harbor Freight solar battery charger, and connect it to the battery when you are not using the car for a while.. I have this on all my cars that live outside, and the batteries are always fully charged...

powersurge said:

I have been with cars for many years, and have never heard so much arguing over a darn 12 volt battery!! Let's get realistic...

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powersurge - you think "on and on" discussions on this forum are excessive? - go to the off-grid solar forums for real excessive!! HOWEVER, battery/capacitance technology (IMO) is one of the important factors in our future success with our conversion to "renewable" based grid (and off-grid) energy supply.

I do agree, the 12 volt battery has literally been "beat to death" with good/bad information, but the more good information, the less dead lead goes to recycle.

arnis said:

Also batteryuniversity and other random sites do mention there are different "100% charged" voltages for AGM batteries (manufacturer based like I understood).

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And there are significant variations between different batteries of the same make and model. I have a "twin" to the battery which rests at 13.25V that rests at 13.0V.

arnis said:

RegGuheert said:

]If it doesn't spend any more time at 14.5V than I have specified, then it has problems.

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I'm sure normal voltage I observe on BMW-s is enough, 13,7-13,9V (fluctuates due to temperature) to not let battery sulfate.

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Yes, you can charge at 13.7V to 13.9V. It just takes longer. But the Nissan LEAF NEVER charges at that voltage. It is either 14.5V (temperature compensated) or 13.1V (not temperature compensated). The result with our LEAF is that the 12V battery sits at about 60% SOC much of the time unless I intervene.

arnis said:

I have OEM BMW battery available and it rests at 12.7V after a long week of float charge and a week of rest.

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That's the symptom of a sulfated lead-acid battery: the resting voltage is lower than when it was new because some lead-sulfate has hardened. The result is that the battery is never fully recharged. If you use a high-quality desulfator, you will be able to recover some or all of the lost capacity.

The large (400Ah) AGMs that I am recovering currently have a resting voltage of 12.65V. Their current capacity is less than 50% of their original capacity when the resting voltage was 13.05V. When I got them, they only had about 100Ah of capacity and resting voltage was below 12.6V. These batteries are L16 style, which is tall and thin. As a result, they sulfate from the bottom up. It may take another six months or a year to recover all of their capacity, but I'm in no hurry since they are not in daily use.

powersurge said:

PS - using this method, I still have a 10 year old battery in great shape in my car.

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The OEM battery in our MY2011 LEAF is over five years old now and works like new by using a similar technique to what you do. I expect to get 10 years or more out of it.

FWIW, I will hate to see that OEM battery go, since it appears to be very well made and it came in a translucent case. That makes checking electrolyte levels a snap. Also FWIW, the battery has only lost about 10% of the water level between the full and empty marks in the five years I have had it.

By comparison, our MY2003 Honda Civic Hybrid used about ALL of the water above the lead in a couple of its cells in about 2.5 years of light use. The charging system in that car is opposite of the LEAF: it always charges at around 14.5V which keeps the battery from getting sulfated. OTOH, it uses significant amounts of water, requiring that water be added occasionally. I just have to be sure not to purchase a battery which cannot be filled.

Checked again. My findings.
It is true, that Leaf tends to keep system voltage at 13V. It does raise it as soon as windshield wipers are used.
If they park for more than 20 seconds voltage drops back to 13 something.

Also it appears that with any cycle (plugging in or putting car in Ready) it first goes to 14.x mode and (I expect) when
amps fall too much (or voltage gets too high) it switches to 13.x mode. And that is perfectly normal.
This can also be tested by draining 12V battery and then cycling the controller.

I also checked for amps going in/out. At 13.x there was 1-2A moving in.
After a wipe voltage raised but amps not much. That means my battery is completely full.
If voltage spikes to 14.6V and amps still don't rush in that clearly says battery is either sulfated or charged.



And most important for convenience: LeafSpy 12V reading is DEAD-ON. It does lag for a second or two but it
keeps numbers very close (max 0.05V difference). Anything less than 0.1V is marginal.
Now the last thing is to measure draw during sleep.

PS. Low end APC UPS devices tend to keep their AGM battery at 13.5V. This always kills them within only few years of use.
This means this voltage is too high. Nissan, most likely, tries to keep 12V not boiling. They, most likely, failed with standby
consumption. My vehicle is fine after a week of doing nothing. Had no opportunity to test for longer.

13.1V definitely charges the battery (very slowly) as OCV is lower for most 12V batteries, even AGM.
Though it is STILL unreasonable to keep system voltage (during READY or CHARGING) below 13.5V.
https://www.google.ee/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwig1bevgdvPAhVib5oKHaCRCyoQFggZMAA&url=http%3A%2F%2Fwww.exide.com%2FMedia%2Ffiles%2FDownloads%2FTransAmer%2FBattery%2520Care%2520and%2520Maintenance%2FBattery%2520Charging%2520%26%2520Storage%2520Guidelines%2520%25205_9_13.pdf&usg=AFQjCNHCuYiOUOfRQ9ieHzyl7IFck-4A6Q&sig2=OIUbOOz_J7_nPZJEnH9xuA&bvm=bv.135475266,d.bGs&cad=rja

arnis said:

... Also it appears that with any cycle (plugging in or putting car in Ready) it first goes to 14.x mode and (I expect) when
amps fall too much (or voltage gets too high) it switches to 13.x mode. And that is perfectly normal.
This can also be tested by draining 12V battery and then cycling the controller.

... Nissan, most likely, tries to keep 12V not boiling. They, most likely, failed with standby
consumption. My vehicle is fine after a week of doing nothing. ...

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Mostly correct.
Where Nissan messed up was on standby power use for some people.

They do not appear to ever do what an inexpensive battery maintainer does.

Most of what they do is all based on current that has been measured coming out of the battery.

When LEAF is OFF they see nothing so they miss standby losses.

arnis said:

And most important for convenience: LeafSpy 12V reading is DEAD-ON. It does lag for a second or two but it
keeps numbers very close (max 0.05V difference). Anything less than 0.1V is marginal.
Now the last thing is to measure draw during sleep.

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This is true for LeafDD as well.
FWIW, 13.1v is great for charging my LiFePO4 battery, not to mention the cells absolutely can't see > 14.4v (which never happens in the Leaf). Even better, Lithium batteries tend to be fine sitting at 50%-80% charge (no such thing as sulfation).

Marktm said:

powersurge said:

I have been with cars for many years, and have never heard so much arguing over a darn 12 volt battery!! Let's get realistic...

Click to expand...

powersurge - you think "on and on" discussions on this forum are excessive? - go to the off-grid solar forums for real excessive!! HOWEVER, battery/capacitance technology (IMO) is one of the important factors in our future success with our conversion to "renewable" based grid (and off-grid) energy supply.

I do agree, the 12 volt battery has literally been "beat to death" with good/bad information, but the more good information, the less dead lead goes to recycle.

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The lead battery industry uses very little new lead from what I understand and unlike the other technologies it is more easily recycled into new batteries without the need for financial subsidies from the government. When a lead battery gets replaced and turned in just about everything in it gets reused including the plastic in the case and lead so that along with how cost effective it is to do so make lead batteries with an effective recycling program quite an environmentally and economically sound choice.

https://www.youtube.com/watch?v=adk4V24Es3g
https://www.youtube.com/watch?v=oJj5iIwF8p4

New observations.
Leaf falls asleep a minute-two after last input. Without OBD adapter it consumes less than 0,3amps, somewhere around 0,15-0,2A. This includes my mandatory aftermarket siren crap.
WITH obd adapter it consumes around 0,4A and if it detects BT device (Leafspy) consumtion jumps to 0,8Amps.
Therefore OBD is big NONO to keep plugged in.

Also I noticed 14,48V reading while L2 charging today. That must have continued for an hour at least. Went for a drive and voltage dropped to 13,06V few minutes after takeoff.

Was able to make a 20A load with head and taillights (incl fogs). I'll try to discharge 12V for half an hour at off state. And take a drive shortly after.

arnis said:

Therefore OBD is big NONO to keep plugged in.

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Agreed. The LEAF with an ELM327 plugged in is MUCH worse on the battery than without it. I used to keep mine plugged in, but now I instead unplug it when I get out. That's harder on the OBDII connector, but better for the battery.

arnis said:

Also I noticed 14,48V reading while L2 charging today. That must have continued for an hour at least. Went for a drive and voltage dropped to 13,06V few minutes after takeoff.

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Yes, that's the 12V charging that I mentioned that occurs during Li-ion charging sometimes. It seems to do this every time in very cold weather (below about 20F), but I have not found the pattern for other conditions (partly because I just don't look for it). FWIW, mine stopped charging the 12V battery after less than one minute today when I charged the car.

I think Nissan would do much better if they set a MINIMUM time to charge at 14.5V of 30 minutes or some such to handle the cases which they currently do not address properly.

arnis said:

Was able to make a 20A load with head and taillights (incl fogs). I'll try to discharge 12V for half an hour at off state. And take a drive shortly after.

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I won't be too surprised surprised if it restores the lost charge fairly well, since it can meter such high currents. The issue is that the measurement resolution in the LEAF is only 1A, so it cannot tell what goes on when the car is off and the current draw is very low, as TimLee has mentioned:

TimLee said:

Where Nissan messed up was on standby power use for some people.

They do not appear to ever do what an inexpensive battery maintainer does.

Most of what they do is all based on current that has been measured coming out of the battery.

When LEAF is OFF they see nothing so they miss standby losses.

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This is clearly seen in the plot I linked to previously:



Note that following the charge by the external Battery Tender at midnight at the end of April 5, 2015, the resting voltage on the AGM is 13.25V. (Note that the charger was unplugged at about 4:00 AM, along with a door to the LEAF being opened. This resulted in an additional load on the battery until the LEAF went back to sleep, followed by a RISE in voltage back to above 13.2V.) Then when the LEAF is plugged in to charge on the morning of April 6, 2015, the LEAF briefly spikes up to 14.35V and then DISCHARGES the battery down to 13.10V. Then following that event, you can see that all of the activity of the LEAF does ABSOLUTELY NOTHING to increase the SOC on the battery. That is why the overall shape of the curve is simply an exponential decline (which is due to whatever standby load there is on the 12V from the LEAF). Simply put, the brief 14.5V spikes and the float voltage of 13.1V did not increase the SOC of the battery in the least. That algorithm WILL keep the battery charged to about 60% SOC (resting voltage of about 12.3V), which is the recipe for sulfation. Of course those who use the windshield wipers frequently will see better results.

My battery tends to be at resting voltage above 12.5V (technically this is not OCV voltage as there is a 0.8A drain during leafspy readout)
I've never charged it myself during 28 months of use. I'll try to get a reading after 24h resting period.

According to dozen pictures searched in google, 12.5-12.6V is way above 80% threshold, except Excide sheet.
Same with my BMW. It rests somewhere around that same voltage, though it has 100Ah battery.

Logic is simple. Leaf should have a drain something like 0,1A. Maximum discharge should be something like 2,4Ah per 24h.
This is more-or-less 5% of total capacity. Battery is almost never drained, only charged at 14.5V and 13.1V (yes, this is a charge voltage if
OCV is below that). As Leaf doesn't crank the engine, it doesn't discharge at all. Except vampire drain.


Tech sheets for BMW-s mention that normal sleep mode draw should be below 50mA for all models. If current above 80mA is registered a fault is registered and user is notified "battery discharging while stopped".
If battery management module registers battery SOC below 60% yellow "PLEASE CHARGE" notification will be shown on the cluster, often happens with vehicles left parked for a month. Below 35% red battery malfunction will be shown.
Current sensor is always active and always counting (it is directly powered by the battery right on the terminal) and it has internal memory.
BMW-s are even programmed to kill comfort access and clock settings in the name of saving the last drop of juice for engine start. This happens about a month/two after falling asleep.
Leaf unfortunately has telematics always awake. Though it is not an excuse as it has many kWh-s in traction battery.

Excide also recommends their batteries to be recharged if they drop below 60% - 12.5V OCV voltage for all types.
If BMW and Exide both are at 60% I believe sulfation happens with anything below that.
According to the graph you showed voltage is above 12.5V the whole time. Also, is it made by OBD adapter? If so then we know
why discharge is so rapid.

Is it popular to have aftermarket siren installed in US? Leased Leafs. Do they have it?

arnis said:

...
Is it popular to have aftermarket siren installed in US? Leased Leafs. Do they have it?

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No.
No.

What has been common is having OBDII adapter hooked up.
Some like Reg unplug it.

I just leave it plugged in.
But I hook up 12V battery maintainer each time.

Probably once or twice a month would be sufficient.
But I don't drive a lot, maybe five times a month.
So mostly my 12V sits in garage on battery maintainer.

TimLee said:

What has been common is having OBDII adapter hooked up.
Some like Reg unplug it.

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To avoid wear and tear on the LEAF's port, I use and extension cable that is routed toward and into the center console...unplug the unit from that easily replaced accessory...

I *once* made the mistake of going out of town for 15 days and left the OBDII adapter plugged in... Due to a discharged 12V battery, came back to a LEAF acting bizarrely and not going to run mode; a jump start from another vehicle, and leaving in park in run mode for a half hour brought back on and off (that was the event that brought me to this thread).

Since then I checked electrolyte levels (fine), purchased a desulfating trickle charger, and run it through a weekend cycle... So far, still on original factory battery from 2011.

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.

If you have a 2015+ Leaf you might be able to use the remote climate control access to charge the battery once a week. Otherwise you might want to use a maintainer. Negative goes to one of the bolts on the thing that looks like an ICE valve cover, in the motor compartment. Others will say there is no need to use a maintainer, and you may not need it with a 2015. Your decision.