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Replacing 12V Battery with LiFePO4 (Video)

Posted: Sat Aug 03, 2019 9:23 pm
by bobkart
This is the battery I went with:

https://www.ohmmu.com/product-page/12v- ... la-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

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Sun Aug 04, 2019 1:40 am
by 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.

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Sun Aug 04, 2019 7:04 am
by Stanton
Oilpan4 wrote:
Sun Aug 04, 2019 1:40 am
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.

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Sun Aug 04, 2019 7:24 am
by iPlug
Stanton wrote:
Sun Aug 04, 2019 7:04 am
Oilpan4 wrote:
Sun Aug 04, 2019 1:40 am
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.

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Sun Aug 04, 2019 1:44 pm
by 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.

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Sun Aug 04, 2019 10:48 pm
by 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.

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Sun Aug 04, 2019 11:09 pm
by Evoforce
Lithium is the way to go!

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Mon Aug 05, 2019 5:59 am
by 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.

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Mon Aug 05, 2019 12:22 pm
by 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...

Re: Replacing 12V Battery with LiFePO4 (Video)

Posted: Mon Aug 05, 2019 12:41 pm
by 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.