REPLACING the 12v OEM battery in a LEAF (any MY or trim level)

[Bombastinator2]

New (to me) 2015 Leaf owner here. For the 12v battery Nissan should have put in a smart charger for optimal battery charging and maintenance. Given the mild temperatures and less vibration under the hood compared with an ICE vehicle, the battery should last and last. Their decision to use a 51R battery size looks like an afterthought toss-in, tall and skinny. I removed it and put in an AGM battery from WEIZE, their Platinum BCI Group 47, 60Ah H5. It fits better, more AH and CCA, and was only $115 with free shipping. Plus it has a 3 year warranty and no core trade-in required. It is a better battery all-around than the 51R and fits in there perfectly. As you can see in my pics, it's just an inch less tall, every bit as long, but a bit wider, and MUCH more powerful, despite only being a few pounds heavier. Frankly I'd recommend routing a battery tender connector cable to the charge port, to facilitate plugging in a a proper battery tender to top-off the battery every few months.

There are two issues with the 12v I know of. One is that some idiot engineer didn’t know how batteries worked and thought 12 was straight not nominal. The result is that if a battery is below exactly 12v (as most ICE engine batteries eventually are) the car won’t boot. So the battery effectively seems to wear out easily and with great frequency. (Even though it sort of doesn’t. It’s just that the car only uses the top edge of its life cycle) It’s so bad that “change the battery” is often the first thing tried if something is wrong. You’d think Nissan would do something about that. But no. It’s been that way for years apparently. There’s a lot of willful stupidity in the design. This isn’t the only facepalm worthy dumb thing. There’s a reason it’s not a big seller. A lot of it is really right though.
The other (Facepam #2) is the 12v charges from the traction battery, and only does it under specific circumstances. So if you don’t meet those circumstances the battery doesn’t get charged (this may have been where you were going with the smart charger)
They fixed the “load in your pants” look of the first version. You’d think there would be more. They fixed a lot of stuff with the second model (which is a reason why I think it’s a good car. There’s been polishing) but they didn’t get ALL the stupid out.

 

[Radek Uchytil]

Levné 20Ah lifepo4.

 

[hradek]

There are two issues with the 12v I know of. One is that some idiot engineer didn’t know how batteries worked and thought 12 was straight not nominal. The result is that if a battery is below exactly 12v (as most ICE engine batteries eventually are) the car won’t boot. So the battery effectively seems to wear out easily and with great frequency. (Even though it sort of doesn’t. It’s just that the car only uses the top edge of its life cycle) It’s so bad that “change the battery” is often the first thing tried if something is wrong. You’d think Nissan would do something about that. But no. It’s been that way for years apparently. There’s a lot of willful stupidity in the design. This isn’t the only facepalm worthy dumb thing. There’s a reason it’s not a big seller. A lot of it is really right though.
The other (Facepam #2) is the 12v charges from the traction battery, and only does it under specific circumstances. So if you don’t meet those circumstances the battery doesn’t get charged (this may have been where you were going with the smart charger)
They fixed the “load in your pants” look of the first version. You’d think there would be more. They fixed a lot of stuff with the second model (which is a reason why I think it’s a good car. There’s been polishing) but they didn’t get ALL the stupid out.

I am finding on my 2022 the car has to fall below 11 volts before you see error. Nissan service tried to tell that it was ok that the stable voltage was 11.8 volts. I was headed for the desert and told them I would charge them the towing charge back to La Quinta if it failed out there. Service replaced the battery but I still carry one of those noco boost https://www.amazon.com/NOCO-GB40-UltraSafe-Lithium

​

​

 

[phog]

Well, the on-board 12v battery management obviously could have been more optimal. On the 2105 Leaf S I just just got the 51R battery in it was of an indeterminate age, but was reading only 12.4 volts as sitting in the car. I thought that to be marginal, so that's why I bought a replacement, the aforementioned Weize AGM battery. After taking the old battery out and charging it, and after a week of sitting, I was surprised to find that the old 51R was still giving me 12.88 volts at rest, and even when clamped with a 50A pile load for 10 seconds it was offering 11.6 volts while under that formidable load. So the battery was still pretty good! The Leaf just wasn't keeping it properly maintained; I bought a new battery unnecessarily. But the beefy group 47, H5 AGM battery I just put in is way better. In testing it was still delivering 13.16 volts a week after buying and initially charging it, and under the 50 amp load test it was still putting out 12.3 volts, while under load (!). So it's a definite upgrade, and for the low cost of it, I'm glad I did it. I am absolutely going to put in a fused smart charger port in the charge area for it, as I have plenty of those things in my motorcycle parts box.
By the way, I LOVE this car! Cost me only four grand, has all new tires on it, and it great for around-town driving. All it needs is some new rear hatch supports and the headlight lenses need a polishing. Other than that, it's like a new car, only 80,000 miles on it and only two "health bars" missing! I Bought an aftermarket cargo privacy cover too. I'm thinking of taking the rear seats out and storing them so there's more cargo room.

 

[Bombastinator2]

Levné 20Ah lifepo4.

This is one common solution. As I understand it, issue is it often doesn’t charge off the alternator so you’ve got to do it manually every so often. There is one that DOES (antigravity) but it’s ridiculously expensive.

 

[Radek Uchytil]

This is one common solution. As I understand it, issue is it often doesn’t charge off the alternator so you’ve got to do it manually every so often. There is one that DOES (antigravity) but it’s ridiculously expensive.

Rather, I see a problem in the sulfation of Pb accumulators. They then reluctantly accept the charge over time and suffer from self-discharge.

 

[fjord]

Thanks to ICE needing a powerful motor (!) to start, we're stuck with the 12V battery, the Achille's heel of EVs.

Sigh.

 

[cornbinder89]

It is not the voltage, the battery but the charge profile which causes all the problems.

I had my 2015 out yesterday in the relative cold, and noticed my 12 volt was being charged to 14.6 almost continuously along the 13 mile trip. Current was less than one amp.
It seams for whatever reason my 2015 seams to have a good charge profile.

 

[Bombastinator2]

Rather, I see a problem in the sulfation of Pb accumulators. They then reluctantly accept the charge over time and suffer from self-discharge.

All I got out of that was something LEAD (LiFepo4 shouldn’t have any so you seem to be talking about lead-acid) has some sort of sulpher problem