12V battery diagnosis and replacement: My experience FWIW

[Bombastinator2]

Pb is way heavier. The replacement I got is both noticeably lighter, and more energy dense. It also has a MUCH greater voltage 'band', and higher resistance to damage from over/deep discharge.
The major factor is to to MAKE SURE the LiFePO4 is DESIGNED for a vehicle, at least as well as you can. It would take an electronics lab expert to verify much of the marketing lies, and omissions of many of these kind of products.
The BMS (battery management system) is absolutely key.
(Note-I scuba. A number of products now use lithium power. Many require a BMS. I've seen a some battery pack BMS fail, when the cells were fine.)

A lot of the much cheaper ones you see on Amazon are not designed for a vehicle. I have no idea if they would work for an EV since they don't have to deal with cranking loads. OTOH, the warranties are usually sketchy, and likely the electronics AND used cells are inferior.
View attachment 4367
What's not to like?
But is is kind of scary to jump into an entirely new tech. Searching Amazon is an ugly and confusing mess.

For some unknown reason I thought you were talking about traction batteries. Apparently the issue is there is info that they won’t charge off a standard alternator, and there is only one brand that will and they want a grand for it. Anti-gravity iirc. If all you need to do is take a LiFePO4 array and plug it in you may have a winner.

 

[Bombastinator2]

I ran my diesel with no problems at -38, and wasn't running pure #1, I ran what ever pump diesel was, but had my trucks equipped with fuel heaters. Only other truck I saw that day was one with Alaska lic plates.

Yeah, fuel heaters are cool. The car the fuel gelled in(a diesel rabbit) didn’t have them. It had to be left in the garage for 3 days with a space heater running.

 

[knightmb]

Many LiFePO4 batteries I've read about have BCM's that do not charge below freezing and/or just shut down below and above critical temperatures. Maybe some don't? Sub $150 LiFePO4 batteries on Amazon do so I suspect that they are not going to do well for a Leaf in cold climates. I'm not worried about temps below 0F but below 32F is going to be common for me in winter. I was looking for a cheap FLA alternative and that probably doesn't exist.

I actually tested such a thing in another topic years back to determine how much power was needed to "start" the Leaf from a LiFePO4 and if you could not charge it back up due to cold temperature, how long would it last, etc. It came out to some really high number, like +500 starts before you would need to charge it back up. That was for a 20 AH size, if you had anything bigger, that's even more starts. In theory, plenty of power to get through a cold time (days, weeks, months) before temperatures warmed back up enough to allow charging again.

 

[BillAinCT]

50Ah LFeiPO4 battery fits Leaf
[email protected]
Amazon ASIN: B0BVD24CMD $120.00

They claim: "Operating temperature: Charge at 0℃-45℃;Discharge at -20℃-60℃." So it appears to not be suited for cold climate but I see that it's perfect for you!

 

[flydiver]

I used the following in SoCAL

50Ah LFeiPO4 battery fits Leaf
[email protected]
Amazon ASIN: B0BVD24CMD $120.00

8mn battery post on Amazon

• Amazon ASIN: B0CY8N2M5M
• $6.99

Hold down clamp needs modification
I have a 3D STL file for mod

Could not find that on Amazon. Batteries of that category seems to really come and go. Most seem to be for storage, golf carts, RV, etc.
It does seem to be a legit Chinese Co, but purchase in the US appears problematic. That's why I went with a company that is US based, and has a track record + user reviews for a good while.
https://www.dongjin-battery.com/lif...y/12v-50ah-lead-acid-replacement-lithium.html

 

[knightmb]

In case anyone was curious, I did price out some LiFePO4 cells made in the USA (not an import from China) a while back for some friends, I was building them a 20 AH battery for their Leaf and the materials at least as far as last year put the price at around $230 in parts. Compared to the over-flowing number of them on Amazon, Ebay for a quarter of the price, I would have to ask if anyone would ever really consider buying a drop in Leaf 12V battery replacement, even if the price was around $250, if it was not sourced from China. Nothing against China, but I think that helps to illustrate the difference in price versus quality. My 12.8V LiFePO4 battery I bought for my Leaf nearly +10 years ago was made in the USA, but had I bought a China clone, would it have lasted this long too?

 

[Learjet]

My battery is over 5 years old, thinking about some PM...why would I want to roll the dice on some China Li, or pay twice the price for an AGM when the original LA went over 5 years? Seriously thinking about a Walmart LA for $150...I could by two of those for the price of an AGM.

 

[LeftieBiker]

There are two main factors in play, here. The quality of the batteries, and the variety of conditions in which they have to function. The OEM starter batteries are of good quality, so when not stressed too much, they last well. When abused or faced with a harsh environment, they don't. Some people want a battery (or whatever part) that will handle worst case scenarios, while others want a part that is economical and will handle light use for many years.

 

[fotajoye]

Here is an link about the same subject, i.e., 12v battery replacement.
https://mynissanleaf.com/threads/12-volt-battery-lead-acid-replacement.33922/#post-629390
And BTW, the LFP battery is still working fine!

 

[Bombastinator2]

I actually tested such a thing in another topic years back to determine how much power was needed to "start" the Leaf from a LiFePO4 and if you could not charge it back up due to cold temperature, how long would it last, etc. It came out to some really high number, like +500 starts before you would need to charge it back up. That was for a 20 AH size, if you had anything bigger, that's even more starts. In theory, plenty of power to get through a cold time (days, weeks, months) before temperatures warmed back up enough to allow charging again.

So a liFepo4 car battery won’t charge off the alternator, but you only have to take it out and charge it once or twice a year. Hmmm…. Would I forget?

 

[knightmb]

So a liFepo4 car battery won’t charge off the alternator, but you only have to take it out and charge it once or twice a year. Hmmm…. Would I forget?

Would only work for an EV, an ICE needs thousands of watts of power to start compared to the mere "hundreds" for two seconds needed to turn on the Leaf. In those kind of temperatures, one would have to be mindful not to run down the 12V battery though in ACC or Standby mode, then you would be up the creek...

 

[Bombastinator2]

Would only work for an EV, an ICE needs thousands of watts of power to start compared to the mere "hundreds" for two seconds needed to turn on the Leaf. In those kind of temperatures, one would have to be mindful not to run down the 12V battery though in ACC or Standby mode, then you would be up the creek...

Might work if I got two and carried a spare and tools to change the battery. Good chance the thing will take forever to charge. Treat it like a spare tire. The killer is the 50a charger not the battery. Apparently it’s most of the cost of that anti-gravity battery. 20a is a lot more doable though.

 

[Bombastinator2]

Could not find that on Amazon. Batteries of that category seems to really come and go. Most seem to be for storage, golf carts, RV, etc.
It does seem to be a legit Chinese Co, but purchase in the US appears problematic. That's why I went with a company that is US based, and has a track record + user reviews for a good while.
https://www.dongjin-battery.com/lif...y/12v-50ah-lead-acid-replacement-lithium.html

The hard one is the charger. 50a charger is like $899 on amazon. The cost seems to go up exponentially with amps. If a low amp charger can be used (I don’t know) it would merely take a longer time. If a 50a charger is needed it isn’t any cheaper than an anti-gravity battery.

TLDNR: crap I got
I’ve got a gfi nema 5-14p, a NMEA 14-50 (that only actually does 40 amps. It’s got a got a 40a gfi breaker on it), and a nema 6-20, if I could charge the thing with a 5-14,or the 6-20 I could do it.

 

[cornbinder89]

Supercapacitors are much better at starting ICE engines. They can store and supply the needed current all in a big single (or multiple) jolt.
To bad Elon bought out Maxwell and killed off the ESM. I read now someone else is making one, but the spec's I saw were not as good as Maxwell's was.
For most small engines that can start with a single lead acid battery, there is little point, but for large diesels, a single Maxwell unit will start them in artic conditions. I used mine to crank at -25F (engine coolant was pre-heated, but oil and Maxwell were not).
A Maxwell unit would work well with a Lithium battery as they only need about 15-20 amps for 10-15 min to charge and provide more current (for a short duration) than 4 gp 31 diesel starting batteries.
They would also be a good choice for an emergency generator that has to sit for months at a time and still start with no notice.

 

[nlspace]

from wikipedia article about Maxwell,

In February 2019, electric vehicle and clean energy company Tesla, Inc. announced that it planned to acquire Maxwell Technologies. The deal closed on May 15, 2019, for US$218 million. In July 2021, Tesla sold Maxwell Technologies branding and ultracapacitor business to a San Diego-based startup called Ucap Power, led by the former vice-president of sales for Maxwell, Gordon Schenk.

 

[cornbinder89]

I have been looking for and have not found any seller of the ESM under the Maxwell name. There is another brand being sold, but its input requirements are different than the Maxwell ESM.
You could before all this came about, buy a 24 volt ESM and charge it from a 12 volt truck system, allowing the advantages of the 24 volt unit (More storage capacity and lower current for the same work) and use it on a 12 volt vehicle.
The other brand does not say it can be charged on 12 volt and supply 24 volt.

 

[LeafNissan1]

Would only work for an EV, an ICE needs thousands of watts of power to start compared to the mere "hundreds" for two seconds needed to turn on the Leaf. In those kind of temperatures, one would have to be mindful not to run down the 12V battery though in ACC or Standby mode, then you would be up the creek...

The question/issue for me in this regard is how well would the lithium battery do, taking into consideration the constant parasitic draw which seems to be inherent with all the Leafs, in comparison to the OEM lead acid battery?

I found this video which is right-on topic and very interesting:

The video deals with a earlier generation Leaf than my 2022 SV, but I've found his numbers to be pretty much what I've experienced with all 3 of my gen 2 Leafs. In the video he mentions that the 12v battery is monitored and charged once every 24 hours via the dc—dc charger, however I haven't noticed this to be happening with any of my Leafs, necessitating a periodic external charge of the 12v battery, in light of the fact that I do not drive the Leaf more than about once a week, usually with trips of 50 miles or less.

 

[Bombastinator2]

The question/issue for me in this regard is how well would the lithium battery do, taking into consideration the constant parasitic draw which seems to be inherent with all the Leafs, in comparison to the OEM lead acid battery?

I found this video which is right-on topic and very interesting:

The video deals with an earlier generation Leaf than my 2022 SV, but I've found his numbers to be pretty much what I've experienced with all 3 of my gen 2 Leafs. In the video he mentions that the 12v battery is monitored and charged once every 24 hours via the dc—dc charger, however I haven't noticed this to be happening with any of my Leafs, necessitating a periodic external charge of the 12v battery, in light of the fact that I do not drive the Leaf more than about once a week, usually with trips of 50 miles or less.

Better. It’s the extra .8v nominal. It will be functional farther into its depletion. Also it will last longer. LiFEpo4 has a lot more charge cycles than lead/acid. One only gets a LiFepo4 or some other replacement battery after the OEM dies though.

 

[flydiver]

The question/issue for me in this regard is how well would the lithium battery do, taking into consideration the constant parasitic draw which seems to be inherent with all the Leafs, in comparison to the OEM lead acid battery?

I found this video which is right-on topic and very interesting:

The video deals with a earlier generation Leaf than my 2022 SV, but I've found his numbers to be pretty much what I've experienced with all 3 of my gen 2 Leafs. In the video he mentions that the 12v battery is monitored and charged once every 24 hours via the dc—dc charger, however I haven't noticed this to be happening with any of my Leafs, necessitating a periodic external charge of the 12v battery, in light of the fact that I do not drive the Leaf more than about once a week, usually with trips of 50 miles or less.

I have a '14. I don't believe or trust the 12v/24 hour charging. It drops too much over a few days to believe it is doing that compared to a similar time frame after an external charge. In 4 years of ownership I've only seen it do it once.

 

[BillAinCT]

I believe the algorithm is every 24 hours and the voltage is low enough to enable it. I've been at my car and noticed the car charging the 12V battery - the one blue light was flashing and shortly afterwards I heard the contactors release and the blue light went off. So I know that it does happen.