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

[mckensie]

My 12v recently began going bad. Out of the blue, my 2020 SV+ wouldn't start one morning, all kinds of idiot lights blazing on the dash. Measured 12v @ 9volts and change.
My preference was to buy an AGM (sealed) battery to upgrade the OEM flooded lead-acid from Nissan (cheapskates!).
Surveying the market revealed this:


a. AutoZone: a Group 51R, Duralast or somesuch brand AGM-------- $280 (incl core chg of $20)
b. RockAuto: a Group 51R, AC Delco AGM ------- $190 (incl. core chg of $12)
c. Walmart: a MightyMax ML35-12INT AGM (replaces DCM0035)------- $75 (no core). Required brass terminal adapters, $15 Amazon, (as the battery comes with M6 female threaded terminals). The battery is about 1 1/4 inch shorter than the Group 51R--I cut 2 pieces of 3/4" plywood, 2.5x5.0 inches, stacked them on top the battery, then the clamp works as intended. Also,
the terminals are on near side of the battery, so battery cables a bit tight to fit, but not bad. The MightyMax is designed
to run a wheelchair, and is deep-cycle type, 35 A-hr @ 20hrs, so should work better than the OEM, plus NO-MAINTENANCE.

https://www.walmart.com/ip/12V-35AH...-with-Interstate-DCM0035-Wheelchair/475753458



For all the trouble these batteries can cause for LEAF owners, Nissan would do well to equip it's EV's with at least an AGM, possibly GEL-type, or even, god forbid, a LITHIUM 12v battery---whaaaat? Or perhaps offer a Li 12v as an upgrade. But, they're apparently only concerned with selling cheap-ass 12v flooded lead acid (200 yr old technology?) batteries that they manufacture. Plus the inevitable replacement of same when the original goes bad, increasing dealer profits. I guess they're Yen-wise, dollar foolish.

 

[Learjet]

look at the ohmmu battery for the leaf, good price working well for me.

"Upgrade your Nissan Leaf 12V battery with a Lithium Iron Phosphate (LiFePO4) battery from Ohmmu $199"

 

[mckensie]

look at the ohmmu battery for the leaf, good price working well for me.

"Upgrade your Nissan Leaf 12V battery with a Lithium Iron Phosphate (LiFePO4) battery from Ohmmu $199"

What are the dimensions of your battery and electrical characteristics?

 

[Learjet]

What are the dimensions of your battery and electrical characteristics?

see their website, it's a group 51r battery. Simple goggle search will take you there.

 

[Learjet]

see their website, it's a group 51r battery....if I recall correctly 40 ah. Simple goggle search will take you there.

 

[cornbinder89]

The only thing "wrong" with the original FLA seams to be sometimes the charging profile seams to be deficient on the Leaf. Switching the AGM will not fix or change that.
If you look at what is printed on the outside of the battery, the Leaf system doesn't come close to meeting those requirements.
I did a bit of digging the manual hoping to find some thing that could be modified to change the charging profile. The only "outside" sensor that has an output that could be manipulated would be the temp sensor on the battery, and my guess is any attempt to change that temp reading drastically in an attempt to raise the voltage would throw a code.
What would work is a translator between what the VCM and the DC-DC convertor to modify the output up. I have no idea how one would go about doing that, it would take someone with more skills in an area I have little to figure out what is needed.
Disconnecting the current sensor, just puts in "fail-safe" mode. not enough to quickly recharge but enough to keep it from going flat.
I was hoping to find some way to adjust to a protocol similar to what I know worked for me in the past.
The Leaf charging, multi stage charge protocol is the best way to charge batteries, but it seams the voltage and current parameters set by Nissan are too conservative for the discharges that the Leaf battery "sees".
I would be looking for a protocol that sees 14.9v for bulk and adsorption, with a tapering current in the adsorption, and a float of 13.4-13.6.
Part of the problem is when Nissan designed the system, they could never know how long the car would be "on" for a given charge cycle, and didn't want to deplete the HV battery while the car is "off", settling for shorter 12v life over optimal charging of the 12 volt and more HV battery cap loss when not being used.
Edit:
I wonder if it would be possible to modify the current sensor? If it is a shunt type, then removing a small amount of the shunt bar should increase the apparent current "seen" by the controller, fool it into thinking the battery is taking more current and keeping the charge rate up longer.
I would want a unit to experiment on and an OEM unit in case it doesn't work or too much change is made.
May be some day I'll find one to fool with and see.

 

[Learjet]

unplug the current sensor will keep the charge at ~14.4 v. but you will also get a DTC. The battery I installed fixes that issue.

 

[cornbinder89]

My understanding is that the LI battery will be harmed in temps below -20F like I saw last winter. Also Li needs a controller, is in inculded?

 

[flydiver]

look at the ohmmu battery for the leaf, good price working well for me.

"Upgrade your Nissan Leaf 12V battery with a Lithium Iron Phosphate (LiFePO4) battery from Ohmmu $199"

I put an Ohmmu in my Prius. when the price dropped $100 bringing it into the same category as Pb. It's been outstanding.
If the price had been as reasonable when I replaced the one in the Leaf, I'd absolutely have gone that route.
As it is I put the battery on a tender 1-2x/month. I don't trust the 2014 leaf charging algorithm.

 

[gmcjetpilot]

OEM made almost 3 hrs, than 1 yr of infamous sudden drain dead but charges... Sick of it, Walmart 5 yrs going strong never died suddenly. I don't charge it directly. Just works. 💪

 

[LeafNissan1]

unplug the current sensor will keep the charge at ~14.4 v. but you will also get a DTC. The battery I installed fixes that issue

My understanding is that the LI battery will be harmed in temps below -20F like I saw last winter. Also Li needs a controller, is in inculded?

I tested disconnecting the sensor and posted my observations in another thread. During the period that I ran with the sensor disconnected, I did not get any DTC's.

I've also considered and researched the Ohmmu and other lithium 12v batteries. Cornbinder asks a good question in regard to a controller for the battery, which is in addition to the battery's BMS. The Leaf's controller for charging the OEM battery is obviously not designed and intended for use with a lithium battery; however, the charging protocol is close enough that many on this forum have had success replacing the OEM 51r FLA (flooded lead-acid) battery with a lithium battery and highly recommend this upgrade. The Leaf's 12v charge controller may even be better with a lithium battery than it is with a FLA battery.

Another thing to consider with any 12v lithium battery replacement would be if the battery's BMS is designed for automotive use or for some other application and if it is an automotive 12v lithium battery, is it specifically designed for an EV or ICE charging system. I'm not saying that any 12v lithium battery will not work with the Leaf, just that these are considerations to be aware of.

Obviously in the case of the Ohmmu battery, the fact that you need to use JIS to SAE adapters would indicate that this battery was not specifically/originally designed exclusively as an automotive battery.

I once saw that EVannex.com had the Ohmmu battery on sale for $149.99 and an additional 10% coupon was available. That was for a very limited time and they are now on "sale" at that website for $265 which is $65 more than the Ohmmu site, but Ohmmu.com has a $19 shipping charge.

When it comes time to replace my OEM battery, which will be 3 years old next January, I've decided to just to go to Costco and buy their 51r Interstate battery for $$124.99 which has Costco's 3 year full-replacement warranty. I think Costco now has an AGM version of this same battery for an additional charge. In the meantime, as I've said in other threads on this topic, always carry a 12v jumper battery due to the sudden unexplained discharge of the 12v battery that I've experienced on 2 of my 2022 Leaf SV's when they were only a few months old.

As for Cornbinder's concern about extreme cold, I'd say that at negative 20 degrees Fahrenheit, all bets are off for any type of battery. Even a discharged FLA will freeze at that temperature, (fully charged FLA is good to negative 80F).

 

[cornbinder89]

As for Cornbinder's concern about extreme cold, I'd say that at negative 20 degrees Fahrenheit, all bets are off for any type of battery. Even a discharged FLA will freeze at that temperature, (fully charged FLA is good to negative 80F).

Well, a completely discharged FLA will freeze, but you shouldn't be totally discharging it in any weather.

I, in a previous life, would live off a FLA battery pack, running a diesel fired heater all night at temps in the -35 to -25 deg range, and never came close to freezing a battery. At the recommend 50% min discharge it still will not freeze at -35F. The battery will not be damaged, at those temperatures. The same can't be said for LI, the Leaf has heaters for the traction battery so they don't have a problem.

I have real world experience not theoretical. It is why I am interested in trying to find out why some have LA battery failures in a few years, and the worse say they replace in a year, while other have reported 5-7 year life and 10 years is not unheard of. I think the problem is partly in the charge regimen and partly in the sensors not conveying accurate information to the controller. There is no reason the Leaf's light duty load should result in lower life expectancy than other FLA cells that are cycled much harder. I'd like to see higher bulk and absorption charge voltage and lower current threshold to switch to float voltage.