12V battery diagnosis and replacement: My experience FWIW

[latebrent]

Leaf spy was occasionally showing sub 12 voltages, so I suspected my 5 year old battery was nearing end of life.

After driving, I left the car off for 5 hours with a Digital volt meter hooked to the battery. Starting at 12.2, every hour the battery voltage dropped about another .1 volts ending up at 11.8.

I took it for a drive to go buy a battery and the leaf charger quickly takes it up to 14V (leafspy reporting). Weather was bad so could not replace the battery immediatley.
However, to quickly mimic the 4 hour "off" wait, I pressed the ON button twice without pressing the brake, the car comes in an an accessory mode. Reading the battery voltage after a few seconds, and the battery was at 11.8V and falling rapidly, turning on more accessories made it drop faster (internal resistance of the battery is getting high!)

This morning after being off for several hour, I simply replaced the battery.

Leaf powered up fine, but threw a few TCU errors (leafspy DTC read) which I cleared in leafspy. Done and Done. Nothing horrible.. just did it. By the way purchased a 51R, bolted right in...
The only wierdness is that the battery clamp was loose prior to replacing the battery.

 

[nlspace]

Great report, thanks for sharing.

 

[khbkhb]

Handy to have a load tester, like this one from amazon. Obviously, we don’t need a lot of cranking ;>, but testing under a resistive load is the best inexpensive way to judge the health of a lead acid battery.

If replacing the battery oneself, it can also be handy to keep the car under power. A bit pricey, but pretty idiot proof. Otherwise, various state/history can be lost. It isn’t the end of the world if you lose it, so this is a bit of gilding the lily, as it were.

 

[JJoynt]

Leaf spy was occasionally showing sub 12 voltages, so I suspected my 5 year old battery was nearing end of life.

After driving, I left the car off for 5 hours with a Digital volt meter hooked to the battery. Starting at 12.2, every hour the battery voltage dropped about another .1 volts ending up at 11.8.

I took it for a drive to go buy a battery and the leaf charger quickly takes it up to 14V (leafspy reporting). Weather was bad so could not replace the battery immediatley.
However, to quickly mimic the 4 hour "off" wait, I pressed the ON button twice without pressing the brake, the car comes in an an accessory mode. Reading the battery voltage after a few seconds, and the battery was at 11.8V and falling rapidly, turning on more accessories made it drop faster (internal resistance of the battery is getting high!)

This morning after being off for several hour, I simply replaced the battery.

Leaf powered up fine, but threw a few TCU errors (leafspy DTC read) which I cleared in leafspy. Done and Done. Nothing horrible.. just did it. By the way purchased a 51R, bolted right in...
The only wierdness is that the battery clamp was loose prior to replacing the battery.

My leaf is 9 years old. I am on my third 12 VDC battery. The first one was OEM Nissan lasted 2 years, second one was Autozone lasted two years. The present one is a bright yellow OPTIMA it has lasted 5 years.

 

[Bombastinator2]

Reading the forum, I see people having good results with LiFepo4 batteries. They’re 12.8 rather than 12 nominal (batteries are a bit like balloons) and leafs don’t seem to like it if their voltage is even a little bit below 12, so it seems like the way out. The problem is I don’t know what battery to buy.

 

[jdcbomb]

2018 SV originally put in service 2018 DEC (5.5 years old, original 12V battery, 31K miles). Vehicle would not start in garage. Jumped the 12V battery with another LEAF sitting next to it and drove it to AutoZone. Replaced with Duralast 51R on the spot. Seems like 12V battery costs been the same for years with this one costing around $230 with a 3 year warranty. Considered AGM / Lithium options but the added cost did not appear to justify the use case.

 

[knightmb]

Reading the forum, I see people having good results with LiFepo4 batteries. They’re 12.8 rather than 12 nominal (batteries are a bit like balloons) and leafs don’t seem to like it if their voltage is even a little bit below 12, so it seems like the way out. The problem is I don’t know what battery to buy.

I often wonder if I should do a side-gig of just find the best LiFePO4 brand batteries I can after some extensive testing (to make sure they were NOT really cheap Lithium other in disguise that catches fire easily), create the adapters needed to connect it up to the Leaf and sell them here. A couple of members here with me have found that at minimum 20 AH in the 12.8V LiFePO4 form works just fine. They used to be crazy expensive 10 years ago, but now they are half the price of a "lead" battery replacements recommended for the Leaf. The near "perfect" experience you get with them (never worry about the Leaf starting in the cold weather, hot weather, etc.) might be more accessible if people had to a way to buy a "drop in replacement" without having to wrangle up all the connectors needed to make it work since the battery is physical smaller, different connectors, etc.

 

[BillAinCT]

Isn't there a problem with LiFePO4 and extended freezing temperatures?

 

[knightmb]

Isn't there a problem with LiFePO4 and extended freezing temperatures?

Depends on how cold. I can only vouch for temperatures down to 0F (-17.7C) from personal experience, but technically they don't sustain damage until around -40F (-40C) , which could technically rule out Alaska or northern parts of Canada, or even a freak weather event in the 48 states most northern or highest mountain peaks in theory, but those also rule out all other types of batteries, FLA, SLA, AGM, etc. because they all take damage below that temperature too. It would be the actual battery temperature versus the air temperature and how long it remained that cold, etc.

 

[cornbinder89]

FLA doesn't sustain damage or freeze until about -80 F if charged. I have experience to -38F

 

[knightmb]

FLA doesn't sustain damage or freeze until about -80 F if charged. I have experience to -38F

I have heard and read about that myself too, but I've never found a FLA battery where the spec sheet reflected that. They all seem to stop at -40F/-40C, so I don't know if that is just a safety thing for a manufacturer to shield itself from lawsuits and they really can go much colder or if the technology has been changed in some way that maybe they did long ago and now cheaper batteries are not as tolerate, etc.

---

 

[Bombastinator2]

Depends on how cold. I can only vouch for temperatures down to 0F (-17.7C) from personal experience, but technically they don't sustain damage until around -40F (-40C) , which could technically rule out Alaska or northern parts of Canada, or even a freak weather event in the 48 states most northern or highest mountain peaks in theory, but those also rule out all other types of batteries, FLA, SLA, AGM, etc. because they all take damage below that temperature too. It would be the actual battery temperature versus the air temperature and how long it remained that cold, etc.

I saw -40 a couple of times in North Dakota, but only as a child. At that temp a whole lot of batteries die. Lead acid or not. It’s a reason old North Dakotans and Minnesotans keep jumper cables in their car along with an emergency snow shovel, brush, and glass scraper. Given global warming I doubt it’s an issue even there anymore.

Silly factoid: I’ve been in “whose is longer?” Discussions over jumper cables.

Another silly factoid: #1 diesel fuel gels at that temp and that is a real pita. You have to warm up the whole car. (My dad was a diesel car early adopter)

 

[cornbinder89]

I have heard and read about that myself too, but I've never found a FLA battery where the spec sheet reflected that. They all seem to stop at -40F/-40C, so I don't know if that is just a safety thing for a manufacturer to shield itself from lawsuits and they really can go much colder or if the technology has been changed in some way that maybe they did long ago and now cheaper batteries are not as tolerate, etc.

FLA loose capacity (ability to supply current) as the temperature falls, (just like our Leaf traction battery) so at -70 F I doubt they would supply much power, but the electrolyte wouldn't freeze and cause damage.
Below about -50F tires freeze and will not flex, so your car becomes worthless below that point, either they come off the beads (if your lucky) or crack and loose air.
The Leaf Traction battery needs to be kept warm below 0 and has heaters to do so, they didn't add one for the 12 volt

 

[cornbinder89]

I saw -40 a couple of times in North Dakota, but only as a child. At that temp a whole lot of batteries die. Lead acid or not. It’s a reason old North Dakotans and Minnesotans keep jumper cables in their car along with an emergency snow shovel, brush, and glass scraper. Given global warming I doubt it’s an issue even there anymore.

Silly factoid: I’ve been in “whose is longer?” Discussions over jumper cables.

Another silly factoid: #1 diesel fuel gels at that temp and that is a real pita. You have to warm up the whole car. (My dad was a diesel car early adopter)

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.

 

[flydiver]

I often wonder if I should do a side-gig of just find the best LiFePO4 brand batteries I can after some extensive testing (to make sure they were NOT really cheap Lithium other in disguise that catches fire easily), create the adapters needed to connect it up to the Leaf and sell them here. A couple of members here with me have found that at minimum 20 AH in the 12.8V LiFePO4 form works just fine. They used to be crazy expensive 10 years ago, but now they are half the price of a "lead" battery replacements recommended for the Leaf. The near "perfect" experience you get with them (never worry about the Leaf starting in the cold weather, hot weather, etc.) might be more accessible if people had to a way to buy a "drop in replacement" without having to wrangle up all the connectors needed to make it work since the battery is physical smaller, different connectors, etc.

After a lot of research and consideration I put an Ohmmu LiFePO4 in my Prius, replacing a 9 year old battery I had been trickle charging every couple weeks to keep going. I've got a small voltage tester wired on to it (thing is in the back under a mat, pain to get to) and it reads a solid 13.1v after sitting 2+ weeks. It reads 13.8v right after a long drive.
It had been ~ $100 more than a 'stock' Pb, but then dropped that amount to make it competitive. Because it IS in the trunk, a Pb needs to be vented so the choices are few and expensive.
So far, I'm convinced. I wish I had done this for the Leaf about a year ago, but wasn't ready for the leap. I STILL externally trickle charge it monthly. I absolutely do not trust the charging algorithm (2014).
This appears to be the one for a Leaf-48 Month Limited Warranty | 12V LFP Vehicle Battery
https://www.ohmmu.com/product-page/12v-lithium-battery-for-nissan-leaf

 

[BillAinCT]

Depends on how cold. I can only vouch for temperatures down to 0F (-17.7C) from personal experience, but technically they don't sustain damage until around -40F (-40C) , which could technically rule out Alaska or northern parts of Canada, or even a freak weather event in the 48 states most northern or highest mountain peaks in theory, but those also rule out all other types of batteries, FLA, SLA, AGM, etc. because they all take damage below that temperature too. It would be the actual battery temperature versus the air temperature and how long it remained that cold, etc.

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.

 

[hradek]

2018 SV originally put in service 2018 DEC (5.5 years old, original 12V battery, 31K miles). Vehicle would not start in garage. Jumped the 12V battery with another LEAF sitting next to it and drove it to AutoZone. Replaced with Duralast 51R on the spot. Seems like 12V battery costs been the same for years with this one costing around $230 with a 3 year warranty. Considered AGM / Lithium options but the added cost did not appear to justify the use case.

I went with the AGM on the first Leaf but sold it and bought a new 2022 Leaf. I am on my third flood cell battery as these are free with my warranty. I think the issue with the house battery is one of over charging as the house battery is charged every time you turn the car on and every time you charge the main battery with little discharge. May help to top off with water every 6 months. I will go with an AGM battery when I have to pay for a battery. Main thing to do is check your voltage every 6 months and replace the battery before it fails something below 11 volts. https://batteryguys.com/pages/the-differences-between-agm-gel-and-flooded-batteries

 

[Bombastinator2]

After a lot of considerations I put an Ohmmu LiFePO4 in my Prius, replacing a 9 year old battery I had been trickle charging every couple weeks to keep going. I've got a small voltage tester wired on to it (thing is in the back under a mat, pain to get to) and it reads a solid 13.1v after sitting 2+ weeks. It reads 13.8v right after a long drive.
It had been ~ $100 more than a 'stock' Pb, but then dropped that amount to make it competitive. Because it IS in the trunk, a Pb needs to be vented so the choices are few and expensive.
So far, I'm convinced.
This appears to be the one for a Leaf-48 Month Limited Warranty | 12V LFP Vehicle Battery
https://www.ohmmu.com/product-page/12v-lithium-battery-for-nissan-leaf

My understanding is energy density isn’t quite as high, which implies to me that there would be a range reduction for equal weight. I don’t know how much lower though, so it might be worth it. On the up side they are generally good for a lot more charge cycles so battery degration would be lower.

 

[flydiver]

My understanding is energy density isn’t quite as high, which implies to me that there would be a range reduction for equal weight. I don’t know how much lower though, so it might be worth it. On the up side they are generally good for a lot more charge cycles so battery degration would be lower.

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.

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.

 

[Agkirk]

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