Replacing 12V Battery with LiFePO4 (Video)

[bobkart]

This is the battery I went with:

https://www.ohmmu.com/product-page/12v-lithium-battery-for-tesla-model-3

Capacity is specified at over 40Ah. Weight came in at 11.6 pounds on a bathroom scale. The stock battery I removed showed 26.6 pounds on the same scale.

Naturally there will be discussions as to whether this is a good idea or not . . . I've read through many such discussions here. Clearly not everyone will see more benefit than cost. It depends on your priorities.

Here is the video:

https://youtu.be/_wcz5oXY1tY

 

[Oilpan4]

I made a LiFePO4 battery out of cells from the now defunct company known as A123 with their "amp20" prizmatics back in 2013 to start my diesel suburban. It still works perfectly.
A great buy considering that on average a lead acid battery would last 13 months and cost well over $100.

I think the leaf is a great vehicle to put a lithium 12v battery in, there is hardly any under hood heat. In an ice you would have to relocate the battery to a more stable climate if the battery resides under the hood.

Main draw back to LiFePO4 is cold numbing.

 

[Stanton]

I think the leaf is a great vehicle to put a lithium 12v battery in, there is hardly any under hood heat. In an ice you would have to relocate the battery to a more stable climate if the battery resides under the hood.

Agreed. I have had a (different) LiFePO4 battery in my Leaf for over 5 years now (impossible with a lead acid in my climate); search the forum for my name and a similar thread title if you want to read about it.

 

[iPlug]

I think the leaf is a great vehicle to put a lithium 12v battery in, there is hardly any under hood heat. In an ice you would have to relocate the battery to a more stable climate if the battery resides under the hood.

Agreed. I have had a (different) LiFePO4 battery in my Leaf for over 5 years now (impossible with a lead acid in my climate); search the forum for my name and a similar thread title if you want to read about it.

Now that enough people have been experimenting with this for a few years, do we have an idea how others are doing with longevity (compared to lead acid)? Certainly at a price, but seems to be a nice fit in your case.

 

[Lothsahn]

I consider myself lucky... I still am on the OEM battery for my 2011, which I think is original. 8... almost 9 years. The lead acid battery definitely should last longer then one year. 3-5 is typical.

 

[Oilpan4]

My diesel suburban from 2006 to 2012 slaughtered lead acid batteries to the tune of one about every year. These were new batteries and not the cheap ones.
This particular 60 amp hour LiFeP04 battery has been in use since 2013 and still going strong.
When it dies I will open it up and repack it with 100ah LiFePO4 prizmatics.
I put it in an old NiCd air craft battery box.

 

[Evoforce]

Lithium is the way to go!

 

[iPlug]

Encouraging to hear personal histories of longevity.

Listed price above is $439. At this price, and considering cost opportunity, would like to either know it would outlast lead acid at least 2x across a widely tested user base or reach near price parity with lead acid before taking the plunge on a lead acid replacement at EOL.

For those having to replace lead acid batteries every 1-2 years in scorching climates, seems to be the way to go now.

 

[LeftieBiker]

For those having to replace lead acid batteries every 1-2 years in scorching climates, seems to be the way to go now.

Yes, and for those living where lead-acid batteries typically last 5+ years, it seems like a waste of money. I doubt one of those lithium packs will last longer than 10 years, and at 4x the price...

 

[bobkart]

Note that longevity isn't the only advantage of these batteries:

- round-trip (charge/discharge) efficiency is considerably higher than lead-acid

- less internal/self discharge

These two mean less total energy is drawn from the traction battery to keep the 12V battery charged. This is probably not very significant, but might matter, depending on your priorities.

- maintenance free and spill-proof . . . granted there are AGM alternatives but those aren't 4x less expensive (more like 2x)

- more stable voltage over the discharge curve

- happy to be left at partial/low states of charge, which causes premature aging on lead-acid (even AGM)

- one-third the weight (for comparable capacities)

Frequency of replacement isn't just something to multiply battery cost by . . . for one, that ignores the labor aspect of such a replacement. Admittedly that is small (under four minutes in my video). But risking a dead vehicle due to a 12V battery dying (or just overdischarging) can have a significant cost. With the longer life, less self-discharge, and more stable (higher) voltages of these batteries at lower states of charge, that risk goes way down (in my estimation).

It's been observed that the Nissan Leaf doesn't do a good job of keeping the 12V battery in a high state of charge. This wears out a lead-acid battery more quickly than if it were more fully charged most of the time (due to sulfation). No such worries for a LiFePO4 battery.

 

[fotajoye]

This post is late to the party; however, Since this topic was first posted, LiFePO4 12 volt batteries have become quite commonly available in automobile service...many are being used as starter batteries in ICEVs. In fact, Elon Musk bending to criticism from his customers, has announced that Lithium batteries will replace the Lead/Acid batteries in the new Tesla models.
I have studied the idea of replacing the group 51R battery in the Nissan Leaf and other than the increased expense, I find little reason not to swap out the Lead battery for a good quality LiFePO4 battery, provided the mandatory BMS can guard against the environment of useage, i.e., it must not allow charging below freezing and must limit operations that can cause damage to the cells.
Some of my findings are surprising; for example; the 51R Lead battery, used in the Leaf, is rated at about 40 amps; but only about half that capacity is truly usable; a Lead battery loses about 1% per day capacity through internal leakage and if not continuously kept fully charged, builds up a sulfur coating over the negative plates and shredding of the positive plates that in time short out the battery; a Lead battery is always chemically active and starts the process of degradation the day acid is added to the core and depending on it's usage can last for periods on average of 3 years.
Today's premium Lead battery is increasing in price to the point of almost reaching parity with good Lithium batteries.
In the 10 years, I drove my 2011 'SV,' I used up three Lead Batteries. I now drive a 2019 'S' and intend to replace the lead battery with a lithium battery at the first indication of weakness.
If you are using a LiFePO4 12 volt battery in your Leaf, please let us know the particulars of your selection and its performance history. I would like to, in time, find a less expensive LiFePO4 battery that will fit the service requirements of the Nissan Leaf.

 

[bobkart]

I replaced mine with this one:

https://www.ohmmu.com/product-page/12v-lithium-battery-for-nissan-leaf

Although at the time there was no Leaf version, it was the Tesla Model 3 version. I believe they're identical spec-wise.

Mine has worked fine since the replacement (2019-08-01). Note the 48-month warranty. I'm not sure of the exact operating range temperature-wise, but the guy you'll probably get on a chat (Sean) is very helpful. Yes the price is on the high side.

The 15 pounds of weight savings is nice.

EDIT: I guess you already know what I used since I mentioned it in the original post! I thought this might have been one of the many *other* LiFePO4 threads.

 

[LeftieBiker]

I have studied the idea of replacing the group 51R battery in the Nissan Leaf and other than the increased expense, I find little reason not to swap out the Lead battery for a good quality LiFePO4 battery, provided the mandatory BMS can guard against the environment of useage, i.e., it must not allow charging below freezing and must limit operations that can cause damage to the cells.

The not charging below freezing requirement, all by itself, makes LiFePo4 batteries a nonstarter (so to speak) in much of North America. They would have to be equipped with heaters that would drain them if not used every week in frigid weather, or that would drain charge from the main pack.

Some of my findings are surprising; for example; the 51R Lead battery, used in the Leaf, is rated at about 40 amps; but only about half that capacity is truly usable; a Lead battery loses about 1% per day capacity through internal leakage and if not continuously kept fully charged, builds up a sulfur coating over the negative plates and shredding of the positive plates that in time short out the battery; a Lead battery is always chemically active and starts the process of degradation the day acid is added to the core and depending on it's usage can last for periods on average of 3 years.

Is this stuff from Battery University? Because they are not the best source of information on batteries. The above is close to worst-case scenario for lead-acid batteries. I've gotten 7+ years from them in ICE vehicles, and a properly sized, good quality 51R can easily last 5 years in a Leaf. A good SLA battery can go six months disconnected without losing more than 5-15% of charge. If you want to compare $75 Chinese brand starting batteries with $400 lithium batteries, be sure to include the warning that sometimes a lithium battery's BMS will fail and kill the battery all by itself; one of the alternate acronyms for "BMS" is "Battery Murdering System." The best, most cost-effective way to deal with a Leaf that is getting dead batteries is:

* Look for a vampire drain.

* If none is found, correct behaviors like leaving the car plugged in but not charging for days.

* Get an AGM battery in the 51R configuration. It may cost twice as much as a 51R store brand starting battery, but that's still half as much (or less) as a lithium battery.

 

[SageBrush]

... swap out the Lead battery for a good quality LiFePO4 battery, provided the mandatory BMS can guard against the environment of useage, i.e., it must not allow charging below freezing and must limit operations that can cause damage to the cells.

Price aside, this BMS requirement is the reason I have not swapped. And even if the 12v has its own reliable BMS, I'm left with the problem of cold spells in the winter when the 12v cannot charge.

@stanton, how did your LFP handle the cold week in Texas ?

 

[knightmb]

If you are using a LiFePO4 12 volt battery in your Leaf, please let us know the particulars of your selection and its performance history. I would like to, in time, find a less expensive LiFePO4 battery that will fit the service requirements of the Nissan Leaf.

Been using mine (which is only a 20ah version) for I think 6 years now without any single issues, my wife on the other hand has gone through several lead-acid batteries in her leaf, not to mention the dead time and helped needed to jump start her car so she could drive. I'm actually going to move it from my 2013 to my 2020 Leaf shortly because I want to see how long the thing will live :mrgreen: I still have the old lead-acid battery on a tender in the garage to keep it healthy in case my wife needs another replacement (which at the rate I check it, she probably will in about another year :| )

 

[jjeff]

... I still have the old lead-acid battery on a tender in the garage to keep it healthy in case my wife needs another replacement (which at the rate I check it, she probably will in about another year :| )

Not sure if this is just a fluke but I also had my old lead-acid battery on a tender in the garage, probably for a couple of years? but I looked at it the other day and it was several inches low on acid, well below the plates Needless to say, I unplugged it and promptly recycled it as I can't believe it's good anymore. I had always thought I was doing good keeping it on a tender but apparently not? now I'm going to have to check my X-1/9 this spring, I've had it on a battery tender for probably 4 years, again thinking I was doing good. I'll be kind of PO'd if its battery is also dry!

 

[LeftieBiker]

For long term storage you probably want a maintainer with less than one amp output. Also, I went to buy a new Batter Tender Jr recently, and the reviews say that for the last couple of years the new ones have had poor quality.

 

[Nubo]

... I still have the old lead-acid battery on a tender in the garage to keep it healthy in case my wife needs another replacement (which at the rate I check it, she probably will in about another year :| )

Not sure if this is just a fluke but I also had my old lead-acid battery on a tender in the garage, probably for a couple of years? but I looked at it the other day and it was several inches low on acid, well below the plates Needless to say, I unplugged it and promptly recycled it as I can't believe it's good anymore. I had always thought I was doing good keeping it on a tender but apparently not? now I'm going to have to check my X-1/9 this spring, I've had it on a battery tender for probably 4 years, again thinking I was doing good. I'll be kind of PO'd if its battery is also dry!

As far as I know, if it's a flooded battery then you need to check electrolyte level periodically even if it's just on a float charge. If the charger has any "desulfating" chicanery then probably need checking more frequently.

 

[SageBrush]

This is the battery I went with:
https://www.ohmmu.com/product-page/12v-lithium-battery-for-tesla-model-3

The link spec is 8.5 Lbs.
I was told by Ohmmu that they reduced the Ahr by half to ~ 20 Ahr so that their product would not cause alerts in the Tesla Model 3

I had a long discussion with them a few weeks ago that ended with them promising to perform a discharge test at 0.1C and to share the results with me. They did not keep their promise so I gave up on the idea of buying a battery from them for my Tesla

 

[jjeff]

As far as I know, if it's a flooded battery then you need to check electrolyte level periodically even if it's just on a float charge. If the charger has any "desulfating" chicanery then probably need checking more frequently.

Yes to your last point, both my float chargers have the occasional pulse for desulfating. Like I said too late for my one battery, I just hope I haven't hurt my X-1/9 battery as that one was almost new when installed. I unplugged that tender a couple months back when I noticed my other battery was very low on acid. Probably should plug it in again for a couple days, then unplug it. I'd check that battery but it's under lots of light things stacked on the hood(where the battery is under) and the car has a cover on it, sounds like a spring project to check that battery.