Solutions to 12 Volt Batteries and Chargers Posted Here

BrockWI said:

Two more cases of the 12v aux battery dying. The first one was while the vehicle was on and moving at 50 mph. For those of you that think this isn't a problem, great, then leave those of us who have experienced it first hand to figure out our problems.

http://www.mynissanleaf.com/viewtopic.php?f=30&t=19767" onclick="window.open(this.href);return false;
and
http://www.mynissanleaf.com/viewtopic.php?f=30&t=19773" onclick="window.open(this.href);return false;

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For those of you who want to see what a failed 12v battery looks like.... Read BrockWI's links. This would be good to know in an emergency. This is exactly why I keep my 12v battery in tip top shape. An ounce of prevention is worth a pound of cure...

69800 said:

The windshield wiper thing is an eye opener. I am suspecting when the load on the battery is such that the voltage drops to a certain value it kicks the charging voltage up to 14.1. I am going to do a test. I will find something to plug into the cigarette lighter that draws 15 amps. Using a dual port adapter I will have my wife watch the voltage each day with a load on and see if it will stay at 14.1 all day every day. I will report back as soon as I get some data. The other reason it would be nice to force the voltage up is on a dark nite. The halogen high beams lose about 25% of their lumens at 13.1 volt vs 14.1 volt. I could force maximum voltage and then my high beams would be brighter on a dark nite out here in moose and deer country. This would also give my battery a proper charge at the same time. Does anyone off the top of their head have and idea of an auto part device that would draw 10 to 15 amps? I will start the test immediately.

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I don't think so. I don't know how quickly the DC->DC responds to loads but it seems to be near instantaneous at increasing and decreasing the amperage it is putting out. I think I would start out by testing to see if you can get the voltage to 14.1 volts through any means other than the known conditions of when the car first starts and when the windshield wipers are on. As for loads to test that turning on your brights/etc. is somewhere in that neighborhood but don't expect that to cause the voltage to change.

QueenBee said:

As for loads to test that turning on your brights/etc. is somewhere in that neighborhood but don't expect that to cause the voltage to change.

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Just turn on the A/C blower to high speed. Most blowers draw 15-20 amps, and with the high beams
the overall current draw should easily approach 30 amps.

So I was day dreaming the other day and was thinking about the day that my 12v finally fails. I have jumper cables but like to be a bit more self reliant than that.

I suppose one solution is carrying around another small 12v battery and remembering to charge it every once in a while. Maybe mounting it somewhere and wiring it to the 12v system with a diode so it stays fully charged.

Then I started thinking about custom DC to DC charger. It would connect to both the 12 volt batteries. When the cars battery was above 12.9 volts it would charge the backup battery using the appropriate charging algorithm for maximum life from the car side which would be being powered by the cars DC-DC. When the cars battery was below 12.9 volts it would charge the cars battery from the aux battery. Then it could monitor the SOC of the backup battery and if that ever got too low you would know that you've used up your reserve capacity, likely because you haven't used the car in too many days.

Or one could just replace the battery early and regularly

I keep a 12v 8 ah SLA battery in the drivers side compartment in the trunk. I have the standard 12v sae plug and a reversing cable with it. In the front I have a sae plug attached to the cars aux battery and snuck out the charge port for trickle charging it weekly. If I need to I can just plug them together and basically parallel them. I have used it more for powering a 12v to USB adapter, but it's nice to know it's there. Again I figure if I have it in there I will never need it, the minute I take it out...

I have in the past used a 12v 250a sla, 2000w inverter and 50 amp charger in place of an alternator in another vehicle

I bought this on sale at the end of January for $48. http://smile.amazon.com/gp/product/B000XQ9MGE/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1" onclick="window.open(this.href);return false;
I was going to keep it on the back porch 'just in case' since the heat is hard on batteries here. I left the blue-tooth OBD device plugged in for a couple days after I got the Leaf, and came out one day to find the battery dead. It now rides around in the back of the Leaf, since I don't trust the battery anymore.

Stupid Question time:
- What is the correct spot to hook the negative terminal of a battery charger to on the 2015? The diagram in the User's Manual is quite small and it is not clear to me where they are indicating is the correct spot for body ground. A photo would be very helpful.

My 2015 is in the shop, for what is likely a bad 12v battery (at least partially). So I will be getting a BatteryMinder or CTEK shortly to maintain the new battery and want to make sure I'm hooking it up correct. (Even if the battery turns out not to be the issue)

Looking at the big piece of metal that resembles a valve cover on an ICE, on top of the "stack" in the motor compartment, you can use the bolts that fasten it down - the equivalent of IVE valve cover bolts - as grounding points. The right side, closest to the battery, is best. There should be one or two bolts on that side, below the stack cover, that you can also use.

After a trickle charge overnight, I observed about 12.88V resting voltage on the 4.5-year-old OEM battery (battery temperature was about 0C). Then I plugged in for a full charge and the 12V charger held the battery at 14.65V during the entire recharge of the main battery, something it rarely ever does. That indicates to me that these 14.XV recharges are NOT triggered by low 12V battery voltage, but rather by something else: perhaps time or number of cycles of some sort.

RegGuheert said:

After a trickle charge overnight, I observed about 12.88V resting voltage on the 4.5-year-old OEM battery (battery temperature was about 0C). Then I plugged in for a full charge and the 12V charger held the battery at 14.65V during the entire recharge of the main battery, something it rarely ever does. That indicates to me that these 14.XV recharges are NOT triggered by low 12V battery voltage, but rather by something else: perhaps time or number of cycles of some sort.

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hmmm, what was duration of this? as best as I can figure, I have never seen a charge cycle last more than about an hour and voltage was 14.20ish i think. definitely not 14.65. I think you have pending issues

DaveinOlyWA said:

hmmm, what was duration of this?

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About four hours.

DaveinOlyWA said:

as best as I can figure, I have never seen a charge cycle last more than about an hour and voltage was 14.20ish i think. definitely not 14.65. I think you have pending issues

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It was cold, so the voltage was higher. At room temperature, it is about 14.4V.

RegGuheert said:

DaveinOlyWA said:

hmmm, what was duration of this?

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About four hours.

DaveinOlyWA said:

as best as I can figure, I have never seen a charge cycle last more than about an hour and voltage was 14.20ish i think. definitely not 14.65. I think you have pending issues

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It was cold, so the voltage was higher. At room temperature, it is about 14.4V.

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ya, sounds like your battery was definitely recovering from a "cold." Rest and warm electrons definitely does the trick!

RegGuheert said:

]It was cold ...

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Someone did report LEAF algorithm does a lot more 14.X 12V charging when cold.

But first report I have seen for the entire pack charging period.

Interesting. Very interesting

LeftieBiker said:

Looking at the big piece of metal that resembles a valve cover on an ICE, on top of the "stack" in the motor compartment, you can use the bolts that fasten it down - the equivalent of IVE valve cover bolts - as grounding points. The right side, closest to the battery, is best. There should be one or two bolts on that side, below the stack cover, that you can also use.

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Thanks, I've got it figured out.

My 12V battery up and died on me yesterday. Completely discharged, measured less than 5V at the terminals. I had to jump it using my wife's car, and left it running for 30 minutes to recharge. Odd because I had been driving it as normal for the week before.

This is on a 2013 SV with ~24k miles on it.

I'm going to take it in to the dealer to get it checked out, but do we have a long-term solution? Preferably one that doesn't involve hooking up to a battery tender every week or so?

I've seen some talk about going to a LiFePO4 12v as a replacement, but I don't see talk about how much Ah is required for the Leaf's application. I don't know much about the requirements - is something like this a decent direct replacement? Shorai Battery I realize the physical size would be different but I'm comfortable I could make a smaller battery fit safely.

Looks like similar threads on this subject recently - with some repetition. This might be of interest:

http://www.mynissanleaf.com/viewtopic.php?f=30&t=21855

erichz said:

I've seen some talk about going to a LiFePO4 12v as a replacement, but I don't see talk about how much Ah is required for the Leaf's application. I don't know much about the requirements - is something like this a decent direct replacement? Shorai Battery I realize the physical size would be different but I'm comfortable I could make a smaller battery fit safely.

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I replaced my 40AHr (stock) 12v with a 20AHr 12v LIFePO4 battery a couple of years ago. I even had a (temp) 12v battery half that capacity in there for a short period of time (not a good mechanical fit). Search for the thread on it (started by me).

Stanton said:

I replaced my 40AHr (stock) 12v with a 20AHr 12v LIFePO4 battery a couple of years ago. I even had a (temp) 12v battery half that capacity in there for a short period of time (not a good mechanical fit). Search for the thread on it (started by me).

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Is that a true 20AHr battery? Most of the ratings I'm seeing online mention "equivalent Ahr" for replacing a Lead-Acid battery - which seems to be 1/3 the rating. So a "27AHr equivalent" Lithium is actually only 9 AHr. Still the CCA rating is about equivalent to our OEM Leaf battery - ~400.

Also, is climate an issue with lithium batteries? Most seem rated only down to 0 degrees F., and we regularly dip down quite a bit below that.

erichz said:

Stanton said:

I replaced my 40AHr (stock) 12v with a 20AHr 12v LIFePO4 battery a couple of years ago. I even had a (temp) 12v battery half that capacity in there for a short period of time (not a good mechanical fit). Search for the thread on it (started by me).

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Is that a true 20AHr battery? Most of the ratings I'm seeing online mention "equivalent Ahr" for replacing a Lead-Acid battery - which seems to be 1/3 the rating. So a "27AHr equivalent" Lithium is actually only 9 AHr. Still the CCA rating is about equivalent to our OEM Leaf battery - ~400.

Also, is climate an issue with lithium batteries? Most seem rated only down to 0 degrees F., and we regularly dip down quite a bit below that.

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It's a "true" 20AHr battery. I don't know about the temperature specs, but these are racing batteries, so I don't imagine they are meant to stay much below freezing (it's warm here in TX).

I don't know about the temperature specs, but these are racing batteries, so I don't imagine they are meant to stay much below freezing (it's warm here in TX).

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The maybe you and the other lithium advocates here shouldn't be suggesting these batteries as a solution for everyone who drives a Leaf. Lithium batteries should not be charged at low ambient temps. AGM batteries may be the better choice for Leafs in typical climates. Much better than the OEM battery, and half the price (or less) of a more complex lithium battery with a potentially problematic BMS.