Changing out the 12V battery in a 2018 Leaf: any gotchas?

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hbquikcomjamesl

Well-known member
Joined
Mar 1, 2021
Messages
208
I just took my Leaf in for inspection/PM/brake fluid, and I'm told that the 12V battery is starting to go.

Are there any "gotchas" on changing out the 12V battery?
 
Nope, it's like changing the 12V battery in any car. That said, the 'unique characteristics' of a Leaf make an AGM battery a good replacement choice.
 
If you decide to use a FLA replacement - like the original, fully charge it right away. My 2012 Leaf required continual charging to keep the SOC at a non-sulfating level - not sure about my new 2021, but will be watching it.
 
Hmm. The only electric vehicle I ever drove prior to the Leaf used FLA batteries for traction. Honking big Exide Loadhog forklift FLA batteries.

It also cut ice.

But back to the matter at hand, re: "it's like changing the 12V battery in any car," I remember when changing out the battery had no "gotchas" at all, not even having to reset the clock (because there wasn't any) or the radio presets (because they were mechanical). And I remember having to reset all of them, and I think I might even remember an alarm system thinking I was trying to hot-wire the car.

How much am I going to have to reset? Not that resetting my radio presets amounts to much beyond punching KUSC into every FM slot and KNX into every AM slot.

I did some window-shopping at the local O'Reilly, and the do-it-yourself battery finder only went up to 2017(!?!!). Anybody know off-hand the specs for a Leaf 12V battery?
 
In my experience I think I've had to re-establish the charging schedule (timers still defined, just have enable), also having to re-establish "auto up" for the drivers' window. Not sure about radio presets 'cause I don't bother with that. I think once after disconnecting the battery, the alarm did go crazy when I reconnected, but disconnecting and reconnecting took care of it. Pretty simple really. I disconnect from time to time just to keep any gremlins at bay, and whenever I decide to give the 12v a full charging session. I've only driven 2012 and 2015 models so ymmv.
 
I did some window-shopping at the local O'Reilly, and the do-it-yourself battery finder only went up to 2017(!?!!). Anybody know off-hand the specs for a Leaf 12V battery?

You want a Group 51R and the "R" is critical. Get a regular Group 51 and you will need one or two longer battery cables as well. A decent (it need not be premium) AGM type battery is definitely preferable for a Leaf, as it will tolerate being less than fully charged much better.
 
Marktm said:
If you decide to use a FLA replacement - like the original, fully charge it right away. My 2012 Leaf required continual charging to keep the SOC at a non-sulfating level - not sure about my new 2021, but will be watching it.

First time to check the new 12 volt battery since Leaf purchase in May. Conditions are - 3 days no driving and voltages taken 24 hours after opening hood (entering the Leaf skews the readings of course). Although difficult to get a "settled voltage" without disconnecting the battery, my best estimate is between 50 and 60% SOC - most likely closer to the 50% SOC. Even considering "parasitic" amperes of 1-2 amps, the "charts" are around 50%. Voltage readings were 12.08 building to 12.18 over 24 hours.

IF, this is correct, it appears my new 2021 Leaf will have the same sulfating problems as my 2012 did - and will now go back to "trickle" charging regularly and use of my 15 amp charger periodically - just to get good life out of a "standard" automotive battery (51R I believe).

I don't have the actual specific battery chart - maybe someone can help on that?
 
I see why "51R" rather than "51."

Hmm. Batterysystems.net says "2018 Nissan Leaf requires a minimum cca rating of: 435"

Not entirely sure why a CCA rating is even relevant to an electric vehicle.

Back to Battery Systems, they list a lot of FLAs with CCA ratings as high as 520, but the AGMs they list only go up to 450. And the CA, RC, and AH@20 ratings for the two listed AGMs are also lower than the listed FLAs.

On the O'Reilly site, they offer an AGM with 450 CCA, 540 CA, 75 minute RC, and for some reason, they claim "Does NOT fit 2018 Leaf." The FLA they have in 51R lists 500CCA, 625 CA, and 85 minutes RC.

On the AutoZone site, the only AGM 51R carries a similar warning, and is only 435 CCA and 45 min. RC. So it's no loss that it also says they don't actually have it in stock.

On the Pep Boys site, they show a Champion-branded AGM with the same (barely adequate) specs as AutoZone, and they don't give a "doesn't fit" warning. And looking at the FLA they offer, they seem to be confused about the difference between 51 and 51R. Then again, some 30 years ago, Pep Boys, at various times, either (1) refused to admit there was such a thing as a 1978 510, and (2) sold me pads without squeak-spring nubs (for Tokico, maybe? My 510 had Nabco brakes, WITH squeak-spring nubs on the pads). So I don't trust Pep Boys any further than I can throw an aircraft carrier.
 
Ignore CCA ratings. The AH rating is significant, but given that the OEM battery only has a capacity of something like 30AH, almost ANY AGM should be able to exceed that. I don't know what's up with the 'does NOT fit' warning, but I've gotten it on Ebay, and it's about as reliable as a stopped clock. If it's 51R then at worst you might have to modify the tray for a bigger battery, or use a universal hold down bar.
 
Went with the O'Reilly AGM. It fits; it works; the only things I lost over the disconnect time were (as "nubo" said) the "Timer 1 Enabled" switch and the current state of the driver screen (it went to the "big" thrust/dynamic braking gauge, rather than the "big" charge indicator). And I had it disconnected long enough to triple-check the polarity.

Looks like the tray (albeit not the hold-down) could accommodate a larger battery.
 
I want to fit the largest 12V Battery I can in my 2018 Series 2 Leaf.

I need to know:

The ID of that largest battery.

The P/N of the large Battery Hold Down Bracket I would need.
 
SalemCat said:
I want to fit the largest 12V Battery I can in my 2018 Series 2 Leaf.

I need to know:

The ID of that largest battery.

The P/N of the large Battery Hold Down Bracket I would need.

Not sure there's any one answer. It's more a function of balancing how much modification/fabricating you're willing to do vs. the amp-hours capacity you want vs. the type/brand of batteries you're considering and their physical dimensions.

If you're looking for more of a recipe, and only having to change the hold-downs, user BrockWI installed a size 34N here https://mynissanleaf.com/viewtopic.php?f=9&t=18129&start=10#p439206

Looks like someone else also installed a size D35 later in that thread.
 
Not sure battery size is the issue as the Leaf (by nature of it's electrical systems) are quite easy on the energy and power requirements. IMO, the problem is how FLA batteries are maintained. Both my 2012 and now my 2021 have not kept the SOC of the OEM battery at a high enough level to prevent sulfation. I can only counter that by periodic trickle charging for as many hours as possible - especially if not used for several days. I know that voltage measurements are not the best method to determine SOC, but all readings/calculations have consistently resulted in about 60-70% SOC level without such trickle charging.

Having said that, the demands on the battery are so mild that even sulfated batteries seem to last quite well! (my 2012 OEM was replaced after 5 years). Using another type of battery (AGM or LI) might be a better alternative, but then you have to consider the charging profile of the Leaf's DC/DC converter - that I have no idea!
 
The AGM (and yes, lithium) batteries seem to work better with the Leaf's crappy 12 volt charging algorithm. It's been suggested that the car was actually designed to use a lithium 12 volt battery, and that makes as much sense as anything else.
 
2018 Leaf

It is clear my original battery was replaced.

The dealership ran a comprehensive test and my battery is fine.

The solution is to trickle charge every few days with https://www.amazon.com/Battery-Tender-021-0123-Junior-Charger/dp/B000CITK8S/ref=asc_df_B000CITK8S?tag=bingshoppinga-20&linkCode=df0&hvadid=80264400674221&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583863979808438&psc=1

So I will.

To the Leaf's defense, this failure occurred after more than seven months of flawless operation.
 
LeftieBiker said:
The AGM (and yes, lithium) batteries seem to work better with the Leaf's crappy 12 volt charging algorithm. It's been suggested that the car was actually designed to use a lithium 12 volt battery, and that makes as much sense as anything else.

Please elaborate on why you express this view. If it has merit, why hasn't Nissan started using an AGM in the Leaf as many vehicle
manufactures have? Yes, there is the cost issue, but at the OEM level, not that significant. Some have indicated that the Leaf's charging
algorithm provides too low of a continuous charging voltage, i.e. 13.1 - 13.5, which is more appropriate for an AGM. If this is the case,
i.e. an ideal charging voltage of 13.1 - 13.5 for an AGM battery, please provide a technical reference/paper indicating such.
Most data on AGMs indicate the ideal charging voltage is very similar to a lead acid battery.
 
We've seen quite a few cases where switching to an AGM battery has resolved the occasional (as opposed to severe vampire drain-related) dead battery problem. The reasoning (some by others, some by me) is that because the AGM is not harmed much by being kept at ~70-80% charge, it can 'wait out' the times when it's undercharged, until the next trip that's long enough and/or has enough use of the wipers, to better charge it. There is also the matter of these batteries almost always having more capacity than the OEM battery. Since the Leaf appears to use voltage as the determining factor in deciding when to bulk charge and when to reduce charge rate, the more slowly rising voltage of a higher capacity AGM battery is likely causing the car to provide a longer bulk charge once it detects low voltage. The little OEM lead-acid battery, with its faster voltage rise, would tend to trigger the charging system to more quickly drop back to the lower amperage/voltage float charge - too quickly to actually charge the battery anywhere near full. So between that and the low capacity of the OEM battery, we see the classic Leaf chronically undercharged battery.
 
lorenfb said:
LeftieBiker said:
The AGM (and yes, lithium) batteries seem to work better with the Leaf's crappy 12 volt charging algorithm. It's been suggested that the car was actually designed to use a lithium 12 volt battery, and that makes as much sense as anything else.

Please elaborate on why you express this view. If it has merit, why hasn't Nissan started using an AGM in the Leaf as many vehicle
manufactures have? Yes, there is the cost issue, but at the OEM level, not that significant. Some have indicated that the Leaf's charging
algorithm provides too low of a continuous charging voltage, i.e. 13.1 - 13.5, which is more appropriate for an AGM. If this is the case,
i.e. an ideal charging voltage of 13.1 - 13.5 for an AGM battery, please provide a technical reference/paper indicating such.
Most data on AGMs indicate the ideal charging voltage is very similar to a lead acid battery.

From what I recall, AGM has a much higher charge acceptance rate, better depth-of-discharge tolerance, and lower self-discharge rate. All 3 would seem to be advantages in LEAF application. AGM's one weakness is lower tolerance of overcharge, which shouldn't be a problem for LEAF.
 
Nubo said:
lorenfb said:
LeftieBiker said:
The AGM (and yes, lithium) batteries seem to work better with the Leaf's crappy 12 volt charging algorithm. It's been suggested that the car was actually designed to use a lithium 12 volt battery, and that makes as much sense as anything else.

Please elaborate on why you express this view. If it has merit, why hasn't Nissan started using an AGM in the Leaf as many vehicle
manufactures have? Yes, there is the cost issue, but at the OEM level, not that significant. Some have indicated that the Leaf's charging
algorithm provides too low of a continuous charging voltage, i.e. 13.1 - 13.5, which is more appropriate for an AGM. If this is the case,
i.e. an ideal charging voltage of 13.1 - 13.5 for an AGM battery, please provide a technical reference/paper indicating such.
Most data on AGMs indicate the ideal charging voltage is very similar to a lead acid battery.

From what I recall, AGM has a much higher charge acceptance rate, better depth-of-discharge tolerance, and lower self-discharge rate. All 3 would seem to be advantages in LEAF application. AGM's one weakness is lower tolerance of overcharge, which shouldn't be a problem for LEAF.

So other than anecdotal references, there's no documented research studies corroborating why AGM batteries might be beneficial
for use in the Leaf versus using a lead acid battery with a larger capacity, i.e. a higher Ahr rating than the OEM 51R, right?
Furthermore, since the Leaf 2 continues to use the 51R, Nissan appears to not see any benefit to using an AGM battery or a Li-ion,
or increasing the low point of its charging voltage. It also appears that no one really knows what the Leaf's 12V battery charging
firmware algorithm is.
 
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